As much as I hate to admit it- some of the best guides out there to study are government publications. Transport Canada put out TP10038-e in 2003, the small fishing vessel safety manual which I could consider as the baseline for the bare minimum seamanship considerations to be had onboard a vessel of any size. You could view this publication as a sort of primer for the watchkeeping mate curriculum; as all of the topics covered in this publication are studied in greater depth by watchkeepers. (also available offsite here)

Longitude: an anglular measurement which is based off of the Prime Meridian. Meridians of longitude run 'vertically' between the north and south pole, but represent distances either east or west of the prime meridian. The distance between lines of longitude will change depending on the latitude (ie. distances between meridians at the equator will vastly differ from distances between meridians at the polar latitudes). All lines of longitude are considered great circles. (wikipedia)

Latitude: a geographic representation of position north or south of the equator. Lines of latitude run 'horizontally' but measure north and south, and are called parallels as opposed to angular measurements because they run parallel to one another measuring northerly or southerly positions. Parallels of latitude (other than the equator) are not great circles because they do not pass through the center of the earth. Latitude is used in chartwork for measuring distances because there is no chart distortion in distance when working with mercator charts. (wikipedia)

Great Circle: the largest circumfrence which can be drawn on any sphere- which in navigation applies to the spherical shape of the earth. A great sphere must divide the earth into 'halves' by passing through the center of the sphere. All lines of longitude are great circles (as they pass from pole to pole), but lines of latitude other than the equator are not great circles. The shortest route possible across the circumfrence of the earth is to follow along the curvature of a great circle. (wikipedia)

Meridians: lines which run from pole to pole connecting areas of equal longitude. Because the earth is considered a sphere (it is in actuality an oblate spheroid) and all meridians conjoin at the north and south poles, the distance between meridians is not equal everywhere (which is mostly relevant when measuring distances on the chart itself). There is one meridian of particular note, called the Prime Meridian, which is where all angular measurements of longitude are referenced from (as in easterly or westerly of the prime meridian). The prime meridian is located near Greenwich in the United Kingdom, which is also where GMT (Greenwich Mean Time), the international time standard, originates. Because of the way both time and longitude are measured, they have a close relation to one another. (wikipedia)

Rhumb Line: a line that cuts across all meridians at the same angle and maintains a constant true direction. Using the Mercator projection, rhumb lines appear as straight lines. To follow a true heading in a straight line irregardless of the meridians is to follow a rhumb line course. If you drew a rhumb line from one pole and followed it all the way to the other, it would form a spirallic loxodrome. (wikipedia)

Mercator Chart: the standard kind of map that is used almost universally because of its simplicity for navigating in small areas. The mercator map represents the world as if it were a rectangular shape rather than a spherical one, and thereby distorts areas at extreme latitudes (this is why antarctica appears giant on world maps), making them appear much larger than they actually are. The mercator chart is straightforward for navigation because drawing a straight line between two points will give a direction to follow to get to your destination. On larger scale maps, this is a problem because the earth is spherical; but for navigating on the coast and at non-extreme latitudes, mercator charts are the best choise.

Video Lessons and Refreshers: Content covering practical chartwork is difficult to understand when written out and presents better as videos to show the different steps. When I was learning chartwork I watched video tutorials extensively. My favorites are Northeastern Maritime Insitute Lessons (playlist covering basic chart plotting into plotting with current, wind, and tide. tide calculations, compass corrections), and Refresh Maritime has a great running fix tutorial and explaination of chart datums.

Dead Reckoning: the process of calculating the current position of an object by using a previously determined position to create a fix (position-fixing). Distance travelled is equal to speed multiplied by time elapsed (which is measured either in hours or minutes), so any two out of these three kinds of information present in a problem will allow the last one to be found. Dead reckoning begins with a known position, such as 1 nautical mile abeam of a waypoint at a certain time- and from there a line of position (LOP) is created in a heading direction (which can be either transferred from or measured by using the parallel ruler to measure off of the nearest chart compass rose). To obtain distance travelled on the chart, the navigation dividers are used to measure incriments of Latitude on the side of the chart (1 degree is equal to 1 minute, and 1 minute is equal to 1 nautical mile), which are transferred onto the line of position. A line of position or fix without time noted is useless; time must always be indicated when plotting on the chart because time is a crucial part of the distance=(speed)x(time) formula. (wikipedia)

Current and Tide: the direction of tidal push, called the set, is expressed as a degree measurement on the compass, referencing the direction tide is pushing (a northerly tide would push towards north). The speed of tidal currents is called the 'rate', and the distance that elapses under tidal effects is called 'drift'. The heading of set is expressed on the chart as an LOP with three arrows in the middle, pointing the direction of travel.

Wind and Leeway: wind measurements are expressed as the cardinal direction they originate from (ie. a northerly wind comes from the north and blows the direction of south). Wind is accounted for mathematically in calculations, but is not plotted at the chart because it is subject to rapid change.

Course Made Good (CMG) and Speed Made Good (SMG): to be 'made good' refers to the actual speed or course which is travelled, as opposed to information which is assumed like the course steered or vessel speed. Because a vessels speed is subject to tidal forces, the speed through the water (STW) is different than the speed made good, which can only be measured by finding a distance travelled to reference against the STW. A course made good is in reference to a vessels heading under environmental forces like tide, which can create a difference between course to steer (CTS) and course made good. A vessel could be steering a course of 180 degrees, but due to the force of tide setting to 170 could be pointing towards 180 (CTS) but travelling in the direction of 170 (CMG). In chartwork, the LOP which represents course made good is expressed with two arrows marking the direction of travel. The CTS heading is marked with one arrow pointing in the direction of travel.

The Navigation Triangle: To create a reprentation of forces affecting navigation, a triangle of velocities or 'nav triangle' can be drawn to measure them. A navigation triangle typically represents either a period of 60 minutes (vessel speed and tidal drift will give a true distance travelled over 60 min) or a period of 30 minutes (all information measured hourly, like speed, must be halved in this case), but can be scaled up or down to represent larger or smaller periods of time. The diagrams shown here represent different orders that the triangle is created in to determine different info, always drawn in the order of A-B, B-C, C-A.

Allowing Current: when allowing the effects of the current to push the vessel, the work order is as such:

• the vessels heading (CTS) is noted and converted into a true bearing (from a gyro, magnetic or compass bearing). Gyro error, or deviation and then variation are accounted for (heading is converted into true bearing),
• gyro error, or deviation and then variation are accounted for (heading is converted into true bearing),
• with the ships heading now converted to a true bearing, the effects of leeway can now be accounted for mathematically,
• with leeway now sorted, the CTS can be plotted on the chart. Track through the water is drawn,
• Tidal effects are accounted for,
• Course over the ground (CMG) is determined. (bearing is converted to true and can be plotted on the chart)

Counteracting Current: when countering the effects of the current to maintain a particular heading, the work order is as such:

• The desired course over the ground is noted and plotted on the chart,
• the direction of current/tidal push is noted,
• course to steer is determined by 'closing' the navigation triangle, (giving a true bearing to be converted later on)
• leeway/wind direction is accounted for at the start of calculations, and is not plotted
• ships heading (CTS) is converted into a compass or gyrocompass heading, gyro error, or variation and deviation are calculated,
• A course to steer is determined (bearing has been converted to a compass heading for the navigator's use)

Position Fixing: it is important for the navigator to take regular fixes to determine and confirm their position. There are many different ways to fix position depending on what information and tools are available to the navigator at the time. It is most common to determine position by drawing two lines of position from diffent known objects (static objects marked on the chart), creating a 'fix' where they intersect that determines the position of the vessel. It is not always possible to have two reliable objects to fix position from, in which case the running fix is used.

Horizontal Sextant Angles: horizontal sextant angle questions and problems in chartwork have very specific wording that can typically stand out and identify them immediately. The telltale sign of a horizontal sextant angle problem is the presence of two angular measurements between two or three points of interest.

TBA

Buoys: Buoys are a type of floating aid to navigation, and are part of the aids to navigation system, along with fixed navigation-aids like lighthouses and electronic aids like RACONS. Buoys, like all aids to navigation, come in many different shapes like nun (cylindrical with conical top), can (cylindrical), cone (conical shape), pillar (frame with solid parts) and spar (a nail-like shape). Buoys are typically a combination of multiple differend aids to navigation, typically being outfitted with bells (audible aids), lights (visual aids), and topmarks (daybeacons). As useful as they are, buoys are not as reliable as fixed navigation aids because their position could potentially shift in heavy weather; therefore heavy reliance on buoys for navigation may open the navigator up to danger (such as using buoys as waypoints as opposed to fixed aids, or sailing too close to buoys that may be displaced from their hazard). Online chart viewers can be helpful in visualizing the buoyage systems around the world.

Buoyage Systems: the world is split into two buoyage systems, IALA A (europe, australia, africa and west asia), and IALA B (north and south america, japan and the phillipines). In IALA A, a port hand lateral buoy will be red, matching the red port-side light of the vessel. In IALA B, a port hand lateral buoy will be green. A saying regarding IALA B regions is 'red, right, return,' to signify keeping a red starboard-hand lateral buoy on the starboard or right-hand side of the vessel, when returning to harbour or proceeding upstream (the direction of which is assumed North on the west coast, and south on the East coast). It is of great importance to be aware of the buoyage system in an area when passage-planning. IALA has a digital dictionary of international aids to marine navigation, which is extremely useful for studying the technical definitions of particular equipment that pop up in examinations (like diaphone horns, occulting light characteristics, etc.).

Lateral Buoys: starboard and port hand buoys indicate which side they should be kept to while passing them, and are colored either red or green (or a combination of both), have either a triangle or a square topmark, and either a red or green light (matching their color). In IALA B, a port-hand lateral buoy is green and should be kept to the port side; and similarily a starboard-hand buoy is red and should be kept to the starboard side when passing. A starboard hand buoy flashes red 1 time every 4 seconds. A Port hand buoy flashes green 1 time every 4 seconds. Bifucation buoys indicate a split into a main and secondary channel or passage. To use the main channel indicated by a bifurcation buoy or marker, the buoy must be kept to the side it primarily indicates; a port-hand bifurcation marker indicates a primary channel to port and a secondary channel to starboard, and a starboard bifurcation would indicate primary channel to starboard and secondary to port. The 'shape' indicating starboard is a triangle (Triangles have 3 points, which make them odd. Starboard contains 9 letters, which makes it odd. Starboard is always associated with odd numbers onboard the vessel and starboard buoys will always be odd-numbered). The 'shape' indicating port is the square (Squares have 4 points, making them even. Port has 4 letters making it even; and it is always associated with even numbers. Port buoys are always even-numbered). This section of TP10038-E clearly explains the IALA B lateral buoys. (wikipedia)

Cardinal Buoys: buoys and markers which indicate that safe water exists in a cardinal direction relative to their position. Cardinal buoys are colored yellow and black, have white lights, and have black triangle-shaped top marks. The topmarks on a cardinal buoy will point with their triangular 'arrows' towards the black part of the buoy to identify it as a north, east, south, or west cardinal buoy. The lights on cardinal buoys are associated with the numbers on the clock; north will flash 1 time every 1 second, east 3 times every 5 seconds, south 6 times with 1 long flash every 10 seconds, and west flashing 9 times in 10 seconds. (wikipedia)

TBA

Resources: the collision regulations are pretty easy to look up examples of. It is important to note that most examples of the collision regulations will be referring to their international version, and therefore it is important to know whether local modifications (ie. canadian modifications) exist. I have multiple books about the collision regulations in my library. I have most widely used and cited Cockroft's 'Collision Avoidance Rules', but have also found Dokmar's 'Colregs Guide' and MTB's 'Seamans's Guide to the Rules of the Road' to be helpful to me, despite none of these publications including the canadian modifications. Other helpful study aids have been phone apps for display of lights and demonstrations of sound signals (I prefer the ones made by madeof.blue for android phones) and captaindamley also has a great colregs elearning module with notes. There are great videos on youtube for people who learn the best by watching videos.

Considerations: the language used within the colregs is extremely technical and the wording of rules should be carefully noted, particularily the differences between words like 'shall' 'may' and 'must'. 'Shall' will always mean that an action must be taken, wheras 'may' indicates that it is compulsory. Vessel size is also very particular and there is a crucial difference between 'greater than __/less than __' and 'of __ or more/ of __ or less'. An example of this would be a vessel less than 20 meters, which references a vessel from 0 m-to 19.9999 meters- any value that is under 20 meters; as opposed to 20 meters or less, which would include vessels 0 meters - 20 meters. It seems quite straightforward, but it is extremely important to have a solid understanding of the wording used in the regulations because it is crucial in interpretation of the rules.

(1) Application: a very wordy and technical rule outlining the application of the collision regulations and whom the rules apply to. The general rule of thumb is that the colregs apply to all bodies of water which are connected to the ocean via navigable waters (ie. the great lakes being connected to the atlantic via the st. lawrence seaway). 'Special rules' mentioned could include local adaptations such as a speed limit imposed upon a harbour. Part 1c states that vessels which are required to display certain lights and shapes as a result of special rules take due care that these lights and shapes are clearly distinguishable and cannot be mistaken for other combinations of lights and shapes.

(2) Responsibility: rule 2 of the collision regulations is extremely important and at very least the intent of the rules shall be memorized by all mariners. It is as follows...

• "Nothing in these rules shall exonerate any vessel, or the owner, master or crew therof, from the consequeneces of any neglect to comply with these rules or the neglect of any precaution which may be required by the ordinary practice of seamen, or by the special circumstances of the case."
• "In construing and complying with these rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may make a departure from the rules necessary to avoid immediate danger."

'A Guide to the Collision Avoidance Rules' by Cockroft breaks this rule down into far more palatable sections. The spirit of the rule has two major components to it; that it is the responsibility of all crew to safely maneuver the vessel; and that if necessary to avoid immediate danger a vessel may make a departure from the rules to avoid collision. It is not justifiable to depart from the rules simply because risk of collision exists with a vessel at some point in the future; the collision regulations may only be disobeyed in the event there is immediate danger and risk of collision. An example of 'precautions required by good seamanship' is the relationship between a ship underway and a ship at anchor; the ship underway is expected to avoid the ship at anchor because the other vessel does not have much maneuverability- but the ship at anchor cannot anchor too close to other boats or neglect to display the symbols which show other vessels that she is a ship at anchor.

(3) General Definitions: an overview of general definitions for terminology used within the collision regulations. Canadian modifications exist for this rule, and supercede rule 3a regarding the definition 'vessel', as the canadian modifications work to seperate between the different subtypes of vessels. Before getting into the 'rules' section of the Canadian Colregs, there is a similar section called 'interpretation' which defines each particular type of special vessel or equipment referred to in the publications; rule 3 presents these terms plainly and as they are to be defined in reference to the regulations. There are multiple 'definitions' sections to the colregs, and each is relevant to the rules associated with the section it is contained within. The most notable definitions in this part are in regard to...

'Seaplanes' does not refer only to planes and is inclusive of helicopters which are capable of landing on the water.

'Underway' refers to a vessel which is not moored, anchored, or aground. A vessel may be underway but not making way if she is not aground/moored/anchored but does not yet have engines up and running.

It is possible for 'restricted visibility' to exist and for vessels to still 'be in sight of one another', which may drastically alter the actions to avoid collision which may be taken.

Also of note are the definitions and examples of vessels 'Not under Command' (NUC) and 'Restricted in their Ability to Maneuver' (RAM)

(4) Application: another application rule. This rule defines that all content follows applies in all conditions of visibility (including restricted visibility). In essence, this means that rules 1-10 apply all the time irregardless of visibility (which is relevant later on)

(5) Lookout:

"Every vessel shall at all times maintain a proper lookout via sight and hearing, as well as all other available means appropriate to the prevailing circumstances and condition, so as to make a full appraisal of the situation and of risk of collision."

Part of maintaining a good lookout is walking around the wheelhouse (or vessel itself) in order to have visibility of blind spots (such as checking the aft quarters from the bridge wings periodically). Depending on the prevailing circumstances and conditions the need for a lookout may be lessened or heightened; irregardless a lookout must be posted at all times. The radar is a tool which may help supplement navigation and lookout duties (re: 'all available means') but which cannot justify the absence of a dediated lookout.
Also of note is that this definition tends to come up frequently during the general seamanship oral examinations. Lookout is an extremely important rule as many times in the past poor lookout and watchkeeping have lead to collisions and have thus set a precedent in the court of law. As the navigator and as the OOW it is important to keep a lookout to the best of your ability even solely to cover your own hide in the event that any collision does occur and the finger is pointed your way (it is very easy to nail OOW on poor lookout in the courts). Even at anchor it is necesary to keep a lookout in the bridge so as to make a full appraisal of the situation; there are many reasons for this, but what stands out to me is that the person in the bridge acting as lookout may want to stand by in the event that the anchor drags (which therefore would classify the vessel as 'underway' and require additional rules which apply to vessels underway). Cockroft's 'collision avoidance rules' has a really great chapter about duties of the lookout, and so does Dokmar's 'colregs guide'.

(6) Safe Speed:

Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions. In determining a safe speed the following factors shall be among those taken into account...

All vessels:
• the state of visibility, (clear or restricted)
• the traffic density including concentrations of fishing vessels or any other vessels,
• the maneoeuverability of the vessel with special refrence to stopping distance and turning ability in the prevailing conditions,
• at night the presence of background light such as from shore lights or from back scatter of her own lights,
• the state of the wind, sea, and current, and the proximity of navigational hazards,
• the draught in relation to the available depth of water,

Additionally, in vessels with operational radar
• the characteristics, efficiency and limitations of the radar equipment,
• any constraints imposed by the radar range scale in use,
• the effect on radar detection of the sea state, weather and other sources of interference,
• the possibilty that small vessels, ice and other floating objects may not be detected by radar at an adequate range
• the number, location and movement of vessels detected by radar,
• the more exact assessment of the visibility what may be possible when radar is used to determine the range of vessels or other objects in the vicinity.

Rule 6 can easily be remembered as having 6 considerations, and then 6 more considerations if you have access to radar. The key point to 'safe speed' is that it is no particular number set in stone and it, obviously, changes depending on the circumstances at hand. For example, a vessel in restricted visibility is expected to reduce her speed greatly in consideration that she cannot see other vessels around and may need to decrease her stopping distance by reducing her speed. Running too slowly can also be a hazard; a vessel which is stopped or moving very slowly has extremely poor maneuverability and may not be able to take appropriate avoiding action in ample time as a result of this. In vessels with radar, the additional rules exist to prevent reckless behavior as a result of overreliance on the equipment, and in consideration of limitations that radar technology inherently has. This rule has Canadian modifications in regards to conduct around grounded/wrecked, dredge or towing vessels. If a vessel is unsure whether their speed and wake may have an adverse effect on nearby working vessels, she shall proceed cautiously and at the minimum speed which allows her to keep on course (also known as 'reducing to her minimum steerageway').

(7) Risk of Collision:

• Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist.
• Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected objects.
• Assumptions shall not be made on the basis of scanty information, especially scanty radar information.
• In determining if risk of collision exists, the following consideratios shall be among those taken into account...
  i. such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change,
  ii. such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range

'All available means' encompasses radar and other bridge equipment (such as AIS, radiocommunications, etc) which can be used to help determine risk of collision with another vessel. Radar and ARPA are fantastic tools for long range collision avoidance if they are used with full consideration of their limitations and faults (such as multiple close radar targets merging together into one target on the screen). An easy way to determine if risk of collision exists with a target sighted visually is to align it with a point of reference on your own vessel (ie. a window wiper blade) and observe it for a few minutes; if it remains in alignment (remaining at a constant bearing) then risk of collision exists. 7d.ii also notes that even if the bearing with a target changes, risk of collision may still exist with targets which are very long or large (visual demonstration of this). It is very important to determine if risk of collision exists well in advance to allow time for action to be taken.

(8) Action to Avoid Collision:

• Any action to avoid collision shall be taken in accordance with the rules of this part, and shall, if the circumstances of the case admit, be positive, made in ample time and with due regard to the observance of good seamanship.
• Any alteraton of course and/or speed to avoid collision shall, if the circumstances of the case admit, be large enough to be readily apparent to another vessel observing visually or by radar; a succession of small alterations of course and/or speed should be avoided.
• If there is sufficient sea room, alteration of course alone may be the most effective action to avoid a close-quarters situation provided that it is made in good time, is substantial and does not result in another close-quarters situation.
• Action taken to avoid collision with another vessel shall be as such to result in passing at a safe distance. The effectiveness of the action shall be carefully checked until the other vessel is finally past and clear.
• If necessary to avoid collision ot allow more time to asses the situation, a vessel shall slacken her speed or take all way off by stopping or reversing her means of propulsion.
• i. A vessel which, by any of these rules, is required not to impede the passage or safe passage of anohter vessel shall, when required by the circumstances of the case, take early action to allow sufficient searoom for the safe passage of the other vessel.
  ii. A vessel required not to impede the passage or the safe passage of another vessel is not relieved of this latter obligation if approaching the other vessel so as to involve risk of collision and shall, when taking action, have full regard to the action which may be required by the rules of this part
  iii. A vessel the passage of which is not to be impeded remains fully obliged to comply with the rules of this Part when the two vessels are approaching one another so as to involve risk of collision.

In this rule, we see much of the reoccuring key phrases and terms such as 'be positive, in able time, and with due regard to the observance of good seamanship' which refers to taking well-planned action in ample time and without hesitation. 8b states that if the circumstances of the case admit any alterations to avoid collision should be large so as to be visually apparent; you want to clearly communicate your actions to the other vessel or vessels in the situation. At night and if the circumstances allow, it is a good practice to alter enough to allow the other vessel to see a different sidelight. 8c states that alteration of course may be the best action to avoid collision, allowing the circumstance in which a reduction or increase of speed is the best course of action. 8f.ii keeps the obligation on the give way vessel to keep out of the way of the stand on vessel until free and clear; even if the position of the vessels changes such that the other vessel appears to become the give way vessel, the original obligation takes priority.

(9) Narrow Channels:

• a vessel proceeding along the course of a narrow channel or fairway shall keep as near to the outer limit of the channel or fairway which lies on her starboard side as is safe and practicable,
• a vessel of less than 20 metres in length or a sailing vessel shall not impede the passage of a vessel which can safely navigate only within a narrow channel or fairway,
• a vessel engaged in fishing shall not impede the passage of any other vessel navigating within a narrow channel or fairway
• a vessel shall not cross a narrow channel or fairway if such crossing impedes the passage of a vessel which can safely navigate only within such channel or fairway. The latter vessel may use the sound signal prescribed in Rule 34(d) if in doubt as to the intention of the crossing vessel,
• i. in a narrow channel or fairway when overtaking can take place only if the vessel to be overtaken has to take action to permit safe passing, the vessel intending to overtake shall indicate her intention by sounding the appropriate signal prescribed in Rule 34(c)(i). The vessel to be overtaken shall, if in agreement, sound the appropriate signal prescribed in Rule 34(c)(ii) and take steps to permit safe passing. If in doubt she may sound the signals prescribed in Rule 34(d),
  ii. this Rule does not relieve the overtaking vessel of her obligation under Rule 13,
• a vessel nearing a bend or an area of a narrow channel or fairway where other vessels may be obscured by an intervening obstruction shall navigate with particular alertness and caution and shall sound the appropriate signal prescribed in Rule 34(e),
• any vessel shall, if the circumstances of the case admit, avoid anchoring in a narrow channel.
Canadian modifications exist for this rule as follows...
• notwithstanding paragraph (d), in the waters of the Great Lakes Basin, a vessel that can safely navigate only within a narrow channel or fairway shall, if a crossing vessel impedes her passage, use the sound signal prescribed in Rule 34(d) if in doubt as to the intention of the crossing vessel.
• notwithstanding paragraph (e), in a narrow channel or fairway in the waters of the Great Lakes Basin, a vessel shall indicate its intention to overtake, or its agreement to being overtaken, as the case may be, by sounding the whistle signals prescribed in Rule 34(j).
• in the Canadian waters of a narrow channel or fairway a barge or an inconspicuous, partly submerged vessel or object shall not be navigated, moored or anchored so as to impede the safe passage of any other vessel or object using those waters.
• notwithstanding paragraph (a) and Rule 14(a), in the Canadian waters of a narrow channel or fairway where there is a current or tidal stream and two power-driven vessels are meeting each other from opposite directions so as to involve risk of collision,
  i. the vessel proceeding with the current or tidal stream shall be the stand-on vessel and shall propose the place of passage and shall indicate the side on which she intends to pass by sounding the appropriate signal prescribed in Rule 34(a) or (g),
  ii. the vessel proceeding against the current or tidal stream shall keep out of the way of the vessel proceeding with the current or tidal stream and shall hold as necessary to permit safe passing,
  iii. the vessel proceeding against the current or tidal stream shall promptly reply to the signal referred to in subparagraph (i) with the same signal, if she is in agreement, and with the sound signal prescribed in Rule 34(d), if she is in doubt.

rule 9 is overall rather straightforward in summary despite its length; vessels should keep to their starboard side, largely not impede other vessels or play around in the center of narrow channels, and use their sound signals to communicate with other traffic when rounding a corner or overtaking. Notably, when overtaking in a narrow channel, the vessel intending to overtake must first ask the vessel to be overtaken for permission (using sound signals or radio communications). Small vessels which are less than 20 meters in length shall nor impede the passage of other vessels which can only navigate within a small area; and vessels engaged in fishing must not impede the passage of any other vessels in the area. The order that vessels 'shall not impede' does not make them 'give way vessels' and the two orders are not the same.

(10) Traffic Seperation Schemes:

• this rule applies to traffic separation schemes adopted by the Organization and does not relieve any vessel of her obligation under any other rule.
• A vessel using a traffic separation scheme shall:
  i. proceed in the appropriate traffic lane in the general direction of traffic flow for that lane,
  ii. so far as practicable keep clear of a traffic separation line or separation zone,
  iii. normally join or leave a traffic lane at the termination of the lane, but when joining or leaving from either side shall do so at as small an angle to the general direction of traffic flow as practicable.
• A vessel shall, so far as practicable, avoid crossing traffic lanes but, if obliged to do so, shall cross on a heading as nearly as practicable at right angles to the general direction of traffic flow.
• i. A vessel shall not use an inshore traffic zone when it can safely use the appropriate traffic lane within the adjacent traffic separation scheme. However, vessels of less than 20 metres in length, sailing vessels and vessels engaged in fishing may use the inshore traffic zone.
  ii. Notwithstanding subparagraph (i), a vessel may use an inshore traffic zone when en route to or from a port, an offshore installation or structure, a pilot station or any other place situated within the inshore traffic zone or to avoid immediate danger.
• A vessel other than a crossing vessel or a vessel joining or leaving a lane shall not normally enter a separation zone or cross a separation line except
  i. in cases of emergency to avoid immediate danger, or
  ii. to engage in fishing within a separation zone.
• a vessel navigating in areas near the terminations of traffic separation schemes shall do so with particular caution.
• a vessel shall so far as practicable avoid anchoring in a traffic separation scheme or in areas near its terminations
• a vessel not using a traffic separation scheme shall avoid it by as wide a margin as is practicable.
• a vessel engaged in fishing shall not impede the passage of any vessel following a traffic lane.
• a vessel of less than 20 metres in length or a sailing vessel shall not impede the safe passage of a power-driven vessel following a traffic lane.
• a vessel restricted in her ability to manoeuvre when engaged in an operation for the maintenance of safety of navigation in a traffic separation scheme is exempted from complying with this Rule to the extent necessary to carry out the operation.
• a vessel restricted in her ability to manoeuvre when engaged in an operation for the laying, servicing or picking up of a submarine cable, within a traffic separation scheme, is exempted from complying with this Rule to the extent necessary to carry out the operation.
canadian modifications for this rule exist as follows...
• subject to paragraphs (q) and (r), paragraphs (b) to (l) apply to traffic separation schemes described in any current Notice to Mariners or Navigational Warning
• a vessel shall use the mandatory routing system, if any, required for its category or the cargo carried that is adopted by the Organization and is described in the publication entitled Ships’ Routeing, as amended from time to time, and shall conform to the relevant provisions in force.
• a power-driven vessel of more than 20 metres in length shall use a traffic separation scheme and the associated routing system, if any, by which it can safely proceed to its destination, that are adopted by the Organization as recommendations and that are in force and described in the publication Ships’ Routeing, as amended from time to time.
• the requirements set out in paragraph (n) or (o) do not apply if there are compelling reasons not to use a particular traffic separation scheme or routing system, and the reasons shall be recorded in the vessel’s logbook.
• paragraphs (b), (c) and (h) do not apply to a vessel engaged in fishing with nets, lines, trawls, trolling lines or other fishing apparatus in or near a routing system located in Canadian waters or fishing zones.
• paragraphs (b), (c), (e) and (h) do not apply to a vessel engaged in laying, servicing or picking up a navigation mark, submarine cable or pipeline, dredging, surveying, underwater operations or launching or recovering aircraft in or near a routing system located in Canadian waters or fishing zones, where that vessel
  i. does not prevent other vessels that use the route from navigating safely,
  ii. identifies itself to approaching vessels and informs them of the location and nature of its operation and of its intentions, and
  iii. informs the Department of Fisheries and Oceans, as soon as possible before the commencement of the operation, of
  A) the nature, location and duration of the operation, and
  B) any necessary cautionary advice concerning the operation.
• a vessel making a transatlantic voyage shall, as far as practicable, avoid crossing the Grand Banks of Newfoundland and Labrador north of 43° north latitude.

This rule only applies to traffic seperation schemes which are adopted by IMO and vessels using the lanes are not relieved of their responsibilities under any other rule. Traffic seperation schemes function like shipping 'highways' and typically exist to help control and direct the flow of traffic in busy shipping lanes. Like rule 9, rule 10 is also very lengthy and conveys a lot of simple information in a very convoluted way. Just like on an actual highway, a vessel using a traffic seperation scheme shall proceed in the appropriate traffic lane, follow the general flow of traffic for that lane and keep clear of the seperation line or zone. Entering or exiting the traffic lane should be done at the termination of the lane and should be done at as small of an angle to the general traffic flow as possible (think of 'merging' on the highway). If a vessel absolutely must sail across the traffic seperation scheme then this should be done as close to 90 degrees to the general diretion of traffic flow as possible. There are inshore traffic lanes which exist only for small traffic (vessels less than 20 meters, sailing vessels and fishing vessels) and those vessels are directed not to impede the passage of power-driven vessels following the lanes; these zones are also to be avoided by large traffic which is using the traffic seperation scheme. The inshore traffic lane can be thought of like a 'shoulder' or 'bike lane' if compared to a highway, and the inshore lane should only be used by larger traffic if there is an immediate danger that must be avoided. Fishing vessels may fish within a traffic seperation scheme but must not imepede the passage of any vessel which is participating in the traffic seperation scheme. The rest of the content covered in the rule are more sensibilities; be careful navigating around the terminations of a traffic lane, try not to anchor in a lane unless there is an emergency, and if you are not participating in the traffic seperation scheme then you must give the area a wide berth to avoid confusion.
Canadian modifications also exist for this rule, giving more allowance to fishing vessels and forcing larger ships to use the traffic lanes and appropriate routing for their cargo type unless there are 'compelling reasons' to not do as such (and such reasons must be recorded in the logbook). The last part of the rule is noteworthy to certain vessels as it is very specific.

(11) Application:

rules in this section apply to vessels in sight of one another.

rule 11 is short and outlines the application of the rules within 'section 2'. Because these rules apply only in the situation where one ship is able to visually sight another, there are situations when they do not apply (which are covered later in the regulations). The rules in this section do not apply to vessels which are detected only via radar.

(12) Sailing Vessels:

• when two sailing vessels are approaching one another, so as to involve risk of collision, one of them shall keep out of the way of the other as follows:
  i. when each has the wind on a different side, the vessel which has the wind on the port side shall keep out of the way of the other;
  ii. when both have the wind on the same side, the vessel which is to windward shall keep out of the way of the vessel which is to leeward;
  iii. if a vessel with the wind on the port side sees a vessel to windward and cannot determine with certainty whether the other vessel has the wind on the port or the starboard side, she shall keep out of the way of the other.
  
• for the purpose of this rule the windward side shall be deemed to be the side opposite to that on which the mainsail is carried or, in the case of a square rigged vessel, the side opposite to that on which the largest fore-and-aft sail is carried.

Rules 8 (action to avoid collision), 13 (overtaking), 16 (action by give way vessel), 17a/b/d (action by stand on vessel) also apply when two sailing vessels are approaching on another (so as to involve risk of collision). It is important to note whether a 'sailing vessel' is also be propelled by machinery even if her sail is up, which would then define her as a 'power-driven vessel'. Cockroft's 'collision avoidance rules' states an exception to the rule; if a sailing vessel is approaching another sailing vesel from more than 22.5 degrees abaft the beam is an overtaking vessel and rule 13 overrides/takes precedence over rule 12 in this scenario. 12a(i) can be thought of as adhering to the 'general' rules for alteration; the vessel with wind to port will ultimately alter to starboard (as she cannot sail into the wind).

(13) Overtaking:

• notwithstanding anything contained in the rules of part B, sections I and II, any vessel overtaking any other shall keep out of the way of the vessel being overtaken,
• a vessel shall be deemed to be overtaking when coming up with another vessel from a direction more than 22.5 degrees abaft her beam, that is, in such a position with reference to the vessel she is overtaking, that at night she would be able to see only the sternlight of that vessel but neither of her sidelights,
• when a vessel is in any doubt as to whether she is overtaking another, she shall assume that this is the case and act accordingly,
• any subsequent alteration of the bearing between the two vessels shall not make the overtaking vessel a crossing vessel within the meaning of these rules or relieve her the duty of keeping clear of the overtaken vessel until she is finally past and clear,

It is the duty of any overtaking vessel (the one doing the overtaking) to keep out of the way of any vessel that she s overtaking (including sailing vessels, fishing vessels and small vessels). Rule 13 takes precedence over rule 12 (sailing vessels) and rule 18 (responsibilities between vessels), requiring vessels which normally may need to avoid one another to keep out of the way of a vessel being overtaken irregardless of what kind of vessel it is. Prime resonsibility for keeping out of the way is allocated to the overtaking vessel in every case as that vesel must be proceeding at greater speed and is more likely to sight the vessel being overtaken at an early stage. A vessel overtaking another is not necessarily required to avoid crossing ahead of the other vessel but altering course or reducing speed in order to pass astern may be the safest form of avoiding action. A power-driven vessel approaching another power-driven vessel from approximately 22.5 degrees abaft the beam should have no doubt as to whether she is overtaking or crossing as in a crossing situation the side-light can be seen, whereas in an overtaking situation the sidelights should not initially be visible (as mentioned in 13b). Because ships in close proximity to one another exert forces of attraction on one another, particularily when a large vessel overtakes a small vessel and at high speeds, it is important for an overtaking vessel to not come too close to a vessel which is being overtaken. Canadian modifications exist for this rule in regards to overtaking within the waters of the Great Lakes Basin and the different lights which may be displayed in the great lakes.

(14) Head on Situation:

• when two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision each shall alter her course to starboard so that each shall pass on the port side of the other,
• such a situation shall be deemed to exist when a vessel sees the other ahead or nearly ahead and by night she could see the masthead lighs of the other in a line or nearly in a line and/or both sidelights and by day she observes the corresponding aspect of the other vessel,
• when a vessel is in any doubt as to whetehr such a situation exists she shall assume that id does exist and act accordingly

Rule 14 places equal responsibility for keeping out of the way on each of the two vesels involved and states exactly what action should be taken by each vessel. This rule applies only to power-driven vessels. The wording of the rule makes it clear that it is based off of the direction of the ships head and not the course made good. Even if it seems that it would be reasonable for both vessels to alter to port and pass on the starboard side of one another, it is not recommended to act against the rules as several collisions have occured as a result of this and have set a precedent.

(15) Crossing Situation:

when two power-driven vesels are crossing so as to involve risk of collision, the vesesl which has the other on her own starboard side shall keep out of the way and shall, if the circumstances of the case admit, avoid crossing ahead of the other vessel.

Like the last, this rule also only applies to power-driven vessels. When crossing in narrow channels and traffic seperation schemes, even if they normally might have priority in a crossing situation, a vessl crossing a narrow channel or traffic lane is required to not impede the safe passage of other vessels which are using these channels or lanes. It should be noted that this rule only applies to vessels which are in sight of one another, so in conditions of restricted visibility the actions to be taken are different. It is important for the give-way vessel to avoid alterations to port in crossing situations as if the give way vessel was to alter to port contrary to the rules, a collision may occur. The stand on vessel has the responsibility to keep their course and speed, allowing the give-way vessel to act- but is not excempt from taking action and must act to avoid collision if the give-way vessel is not acting. Canadian modifications for this rule exist in regards to vessels crossing rivers (in canadian waers a vessel crossing a river shall keep out of the way of a power-driven vessel ascending or descending the river, except on the St Lawrence River seaward of Ile Rouge)

(16) Action by Give-way Vessel:

every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear

The key words in rule 16 are the direction for the give-way vessel to take 'early and substantial action' to keep well clear. Rule 8 quite clearly defines the requirements of both the stand-on and give-way vessels when taking action to avoid collision. Rule 16 applies to vessls which are in sight of one another.

(17) Action by Stand-on Vessel:

• i. where one of two vessels is to keep out of the way, the other shall keep her course and speed,
  ii. the latter vessel may however take action to avoid collision by her manoeuvre alone, as soon as it becomes apparent to her tha the vessel required to keep out of the way is not taking appropriate action in compliance with these rules,
  
• when, from any cause, the vessel required to keep her course and speed finds herself so close that collision cannot be avoided by the action of the give-way vessel alone, she shall take such action as will best aid to avoid collision,
• a power-driven vessel which takes action in a crossing situation in accordance with subparagraph a(ii) of this rule to avoid collision with another power-driven vessel shall, if the circumstances of the case admit, not alter course to port for a vessel on her own port side,
• this rule does not relieve the give-way vessel of her obligation to keep out of the way

Rule 17 is a little longer than 16, its 'companion' rule. Most importantly in the rule is the designation that the stand-on vessel must take action itself if it becomes apparent that the give-way vessel is not acting to avoid collision as it should (for some reason or another). A question which is often asked on examinations is in regards to 17b, in which a vessel which finds herself in an imminent collision and must take whatever action she is able to take in order to best avoid collision. Rule 17 permits a stand-on vessel to take action to avoid collision earlier than rule 2 (responsibility) would. It is important, if one finds themself in doubt as to the other vessel's intentions, that they use the sound signal prescribed in rule 34 to communicate and convey their confusion. 17b does not prescribe any particular action which must be taken by a stand-on vessel (17c mentions the avoidance of an alteration to port) and leaves it up to the navigator to 'take such action as will best aid to avoid collision'. It can be thought of that collision situations have four stages;

1. at long range before risk of collision exists, both vessels are free to act
2. when risk of collision first begins to apply, the give-way vessel is required to take 'early and substantial action' and the stand on vessel must keep her course and speed.
3. when it becomes apparent that the give0way vessel is not taking action as required, the stand on vessel is then permitted to take avoiding action (after sounding their whistle to express confusion about intent)- but very importantly must not make any alterations to port in the case that there is traffic to the port side.
4. when collision cannot be avoided by the give-way vessel alone, the stand on vessel shall (must) take any action necessary to avoid a collision

(18) Responsibilities Between Vessels:

except where rules 9 (narrow channels), 10 (traffic seperation schemes) and 13 (overtaking) otherwise require:
• a power driven vessel underway shall keep out of the way of;
  i. a vessel not under command,
  ii. a vessel restricted in her ability to manoeuvre,
  iii. a vessel engaged in fishing,
  iv. a sailing vessel
• a sailing vessel underway shall keep out of the way of;
  i. a vessel not under command,
  ii. a vessel restricted in her ability to manoeuvre,
  iii. a vessel engaged in fishing,
• a vessel engaged in fishing when underway shall, so far as possible, keep out of the way of;
  i. a vessel not under command,
  ii. a vessel restricted in her ability to manoeuvre,
• i. any vessel other than a vessel not under command or a vessel restricte din her ability to manoeuvre shall, if the circumstances of the case admit, avoid impeding the safe passage of a vessel constrained by her draught, exhibiting the signals in Rule 28,
  ii. a vessel constrained by her draught shall navigate with particular caustion having full regard to her special condition,
• a seaplane on the water shall, in general, keep well clear of all vessels and avoid impeding their navigation. In circumstances, however, where risk of collision exists, she shall complay with the rules of this part.
• i. a WIG craft shall, when taking off, landing and in flight near the surface, keep welll clear of all other vessels and avoid impeding their navigation,
  ii. a WIG craft operating on the water surface shall comply with the rules of this part as a power driven vessel.

This rule breaks down the different 'classifications' between vessels and establishes, for the most part, who takes 'priority' over other vessels in mindfulness of their overall maneouverability characteristics. It is of note that most vessels are classified as power-driven vessels, and take on these other types depending on the circumstances they find themselves in, or by the work that they perform. For example, a fishing boat may be normally considered as a power-driven vessel, but while actively engaged in fishing takes on the classification of a 'vessel engaged in fishing'. All of these 'states' of vessels are covered and defined in rule 3 (general definitions). A tug which is towing cargo is not considered as anything other than a power-driven vessel unless the nature of her work severely restricts her maneouvrability. It is important for each vessel to display the proper lights and shapes in accordance with her status in order for other vessels to responsibly navigate in and around her.

(19) Conduct of Vessels in Restricted Visibility:

• this rule applies to vessels not in sight of one another when navigating in or near an area of restricted visibility,
• every vessel shall proceeed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. A power-driven vessel shall have her engines available for immediate maneouvre,
• every vessel shall have due regard to the prevailing circumstances and conditions of restricted visibility when complying with the rules of section I of this part,
• a vessel which detects by radar alone the presence of another vessel shall determine if a close-quarters situation is developing and/or risk of collision exists. If so, she shall take avoiding action in ample time, provided that when such action consists of an alteration of course, so far as possible the following shall be avoided:
  i. an alteration of course to port for a vessel forward of the beam, other than for a vessel being overtaken,
  ii. an alteration of course towards a vessel abeam or abaft the beam,
• except where it has been determined that a risk of collision does not exist, every vessel which hears apparently forward of her beam the fog signal of another vessel, or which cannot avoid a close-quarters situation with another vessel forward of her beam, shall reduce her speed to the minimum at which she can be kept on her course. She shall if necessary take all her way off and in any event navigate with extreme caution until danger of collision is over,

Rule 19 is the only rule which falls under section 3, dealing with vessels which are not in sight of one another. Because vessels are not in sight of one another, rules which are contained within section 2 may not necessarily apply (ie. in the case of targets which are detected only via radar). Rule 19 applies both when in restricted visibility and when near restricted visibility; if a vessel was on the edge of a fog bank but not necessarily in the bank, then rule 19 would still apply. When navigating in or near restricted visibility it is extremely important to sound the fog signal as prescribed in Rule 34 (which we will cover later). Part of 'having due regard to the prevailing circumstances and conditions' may be enhanced watchkeeping procedures; such as the additional posting of lookouts to watch or listen for the signals of other vessels in the area. 19e poses the scenario where another vessel is detected but the exact position may not be known; therefore it is imperative to reduce speed so as to minimize damage in the event of collision and to hold off on recklessly altering until the position of the other vessel is determined, at which point immediate action can be taken to avoid collision. 19d parts i and ii exist to help establish responsibilities and general cardinals while in restricted visibility, when rules like 14 and 15 do not apply to dictate avoiding action. Restricted visibility has no particular parameters for classification; restricted visibility is considered to exist when visibility is obscured, obviously; the measures and caution which should be had depend on the range of visibility within the fog (which can be determined quite accurately using radar ranging off of known objects or landmarks). 19e comes up often in examinations and has many nuances in the construction of the rule which should be carefully noted; 'she shall if necessary' means that if it is deemed necessary it must done,

(20) Application:

• rules of this part shall be complied with in all weathers,
• the rules concerning lights shall be complied with from sunset to sunrise and during such times no other lights shall be exhibited, except such lights as cannot be mistaken for the lights specified in these rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper look-out,
• the lights prescribed by these rules shall, if carried, also be exhibited from sunrise to sunset in restricted visibility and may be exhibited in all other circumstances when it is deemed necessary,
• the rules concerning shapes shall be complied with by day
• the lights and shapes specified in these rules shall comply with the provisions of annex I to these regulations

Outlines the application of rules for this section. Even small vessels are expected to comply with the rules concerning lights and shapes in all weather conditions. If any lights are lost or extinguished they must be replaced or repaired as soon as possible. 'No other lights shall be exhibited' is to deter vessels from running with their working lights on at night, which both obscures their navigational lights and also diminishes the nighttime vision of other vessels in the area, though there are specific situations in which it is required for the decks to be illuminated (rule 30c). There is a significance in the use of 'underway' as a status which dictates lights must be switched on, as a vessel is to be considered as 'underway' anytime she is not tied to the dock, aground, or anchored (in the event that an anchored vessel begins to drag anchor, she also becomes 'underway').

(21) Definitions:

• 'masthead light' means a white light placed over the fore and aft centerline of the vessel showing an unbroken light over an arc of the horizon of 225 degrees and so fixed as to show the light from right ahead to 22.5 degrees abaft the beam on either side of the vessel,
• 'sidelights' means a green light on the starboard side and a red light on the port side each showing an unbroken light over an arc of the horizon of 112.5 degrees and so fixed as to show the light from right ahead to 22.5 degrees abaft the beam on its respective side. In a vessel of less than 20 meters in length the sidelights may be combined in one lantern carried on the fore and aft centerline of the vessel,
• 'sternlight' means a white light placed as nearly as practicable at the sterm showing an unbroken light over an arc of the horizon of 135 degrees and so fixed as to show the light 67.5 degrees from right aft on each side of the vessel,
• 'towing light' means a yellow light having the same characteristic as the 'sternlight' defined in paragraph (c) of this rule,
• 'all-around light' means a light showing an unbroken light over an arc of the horizon of 360 degrees,
• 'flashing light' means a light flashing at regular intervals at a frequency of 120 flashes or more per minute,
Additional Canadian Modifications for this rule exist as follows;
• 'special flashing light' means a yellow light flashing at regular intervals at a frequency of 50 to 70 flashes per minute, placed as far forward and as nearly as practicable on the fore and aft centerline of a vessel and showing an unbroken light over an arc of the horizon of not less than 180 degrees nor more than 225 degrees and so fixed as to show the light from right ahead to abeam and not more than 22.5 degrees abaft the mean on either side of the vessel,
• 'blue flashing light' means a blue all-around light flashing at regular intervals at a frequency of 50-70 flashes per minute,

As for all parts, it is important to know the specific definitions for terminology which is used within the section (as this is what is asked on the examinations). The canadian modifications to this rule are both in reference to lights which flash at a different frequency than the 'flashing lights' in international rules, and while the wording for 'special flashing lights' is very wordy- it boils down to having an arc of visibility which is no greater than that of the masthead light and which is visible over 180 degrees (the forward half of the vessel) at least. When referring to 'an unbroken light over an arc of the horizon' this means that there are no blind sectors whereby the light in question would not be visible.

(22) Visibility of Lights:

the lights prescribed in these rules shall have an intensity as specified in section 8 of annex I to these regulations so as to be visible at the following minimum ranges:
• in vessels of 50 meters or more in length;
  - a masthead light, 6 miles
  - sidelights, 3 miles
  - a sternlight, 3 miles
  - a towing light, 3 miles
  - a white, red, green or yellow all-around light, 3 miles
• in vessels of 12 meters or more in length but less than 50 meters in length;
  - a masthead light, 3 miles
  - sidelights, 2 miles
  - a sternlight, 2 miles
  - a towing light, 2 miles
  - a white, red, green or yellow all-around light, 2 miles
• in vessels of less than 12 meters in length;
  - a masthead light, 2 miles
  - sidelights, 1 mile
  - a sternlight, 2 miles
  - a towing light, 2 miles
  - a white, red, green or yellow all-around light, 2 miles
• in inconspicuous, partly submerged vessels or objects being towed;
  - a white all-around light, 3 miles,
Canadian modifications exist as follows...
• in vessels exhibiting;
  - a special flashing light, 2 miles
  - a blue flashing light, 2 miles

Because the canadian modifications for special canadian lights have no lengths associated with their visibility, it can be thought of that a blue flashing light and a special flashing light will always have a visible range of 2 miles. Becasuse of changes to environmental conditions, it may be possible for lights to be seen over a greater distance than specified. Masthead lights are always visible at the greatest range and are the typically always the first lights which are brought into view.

(23) Power-Driven Vessels Underway:

• a power-driven vessel underway shall exhibit:
  i. a masthead light forward,
  ii. a second masthead light abaft of and higher than the forward one; except that a vessel of less than 50 meters in length shall not be obliged to exhibit such light but may do so,
  iii. sidelights,
  iv. a sternlight
• an air cushion vessel when operating in the non-displacement mode shall, in addition to the lights prescribed in paragraph (a) of this rule, exhibit an all-around flashing yellow light,
• a WIG craft only when taking off, landing and in flight near the surface shall, in addition to the lights prescribed in paragraph (a) of this rule, exhibit a high intensity all-around flashing red light,
• i. a power driven vessel of less than 12 meters in length may in lieu of the lights prescribed in paragraph (a) of this rule exhibit an all-around white light and sidelights,
  ii. a power driven vessel of less than 7 meters in length whose maximum speed does not exceed 7 knots may in lieu of the lights prescribed in paragraph (a) of this rule exhibit an all-around white light and shall, if practicable, also exhibit sidelights,
  iii. the masthead light of all-around white light on a power driven vessel of less than 12 meters in length may be displaced from the fore aand aft centreline of the vessel if fitting is not practicable, provided that the sidelights are conbined in one lantern which shall be carried on the fore and aft centreline of the vessel or located as nearly as practicable in the same for and aft line as the masthead light or the all-around white light,
The following are Canadian modifications to the rules....
• Rule 23d(ii) does not apply to a canadian power driven vessel in any waters or to a non-caadian power driven vessel in the canadian waters of a roadstead, harbour, lake or inland waterway,
• in the waters of the Great Lakes Basin, a power driven vessel when underway may, instead of the second masthead light and sternlight prescribed in paragraph (a), carry, in the position of the second masthead light, a single all-around white light or two such lights placed not over 800 milimeters apart horizontally, one on either side of the keel and so arranged that one or the other or both shall be visible from any angle of approach and for the same minimum range as the masthead lights.

In most cases, vessels are by default a 'power driven vessel' and, except in certain cases, additional rules and provisions will just apply or modify the lights prescribed in rule 23 to indicate status and identity.

(24) Towing and Pushing Vessels Underway:

• a power driven vessel when towing shall exhibit;
  i. instead of the light prescribed in rule 23a(i) or (ii), two masthead lights in a vertical line. When the length of the tow, measuring from the stern of the towing vessel to the after end of the tow exceeds 200 meters, three such lights in a vertical line.
  ii. sidelights
  iii. a sternlight
  iv. a towing light in a vertical line above the sternlight
  v. when the length of the tow exceeds 200 meters, a diamond shape where it can best be seen
• when a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit they shall be regarded as a power-driven vessel and exhibit the lights prescribed in rule 23,
• a power driven vessel when pushing ahead or towing alongside, except in the case of a composite unit, shall exhibit;
  i. instead of the light prescribed in rule 23a(i) or (ii), two masthead lights in a vertical line,
  ii. sidelights,
  iii. a sternlight,
• a power driven vessel to which paragraph a or c of this rule applies shall also comply with rule 23a(ii).
• a vessel or object being towed, other than those mentioned in paragraph (g) of this rule, shall exhibit;
  i. sidelights,
  ii. a sternlight,
  iii. when the length of the tow exceeds 200 meters, a diamond shape where it can best be seen,
• provided that any number of vessels being towed alongside or pushed in a group shall be lighted as one vessel,
  i. a vessel being pushed ahead, not being part of a composite unit, shall exhibit at the forward end, sidelights,
  ii. a vessel being towed alongside shall exhibit a sternlight and at the forward end, sidelights,
• an inconspicuous, partly submerged vessel or object, or comination of such vessels or objects being towed, shall exhibit;
  i. if it is less than 25 meters in breadth, one all-around white light at or near the forward end and one at or near the after end except that dracones need not exhibit a light at or near the forward end,
  ii. if it is 25 meters or more in breadth, two additional all-around white lights at or near the extremities of its breadth,
  iii. if it exceeds 100 meters in length, additional all-around white lights between the lights prescribed in subparagraphs (i) and (ii) so that the distance between the lights shall not exceeed 100 meters,
  iv. a diamond shape at or near the aftermost extremity of the last vessel or object being towed and if the length of the tow exceeds 200 meters an additional diamond shape where it can best be seen and located as far forward as is practicable
• where from any sufficient cause it is impracticable for a vessel or object being towed to exhibit the lights or shapes prescribed in paragraph (e) or (g) of this rule, all possible measures shall be taken to light the vessel or object towed, or at last to indicate the presence of such vessel or object,
• where from any sufficient cause it is impracticable for a vessel not normally engaged in towing operations to display the lights prescribed in paragraph (a) or (c) of this rule, such vessel shall not be required to exhibit those lights when engaged in towing another vessel in distress or otherwise in need of assistance. All possible measures shall be taken to indicate the nature of the relationship between the towing vessel and the vessel being towed as authorized by rule 36, in particular by illuminating the towline.
Additional canadian modifications exist as follows...
• for the purpose of paragraph (h), if it is impracticable for a barge being towed to comply with paragraph (e) within the canadian waters of a roadstead, harbour, river, lake or inland waterway, it shall carry one all-around white light at each end; however, in a case where two or more barges are grouped together, the barges,
  i. may instead carry one all-around white light at the end of each group, and,
  ii. if the total length of the group exceeds 100 meters and if the group is lighted in accordance with subparagraph (i), shall carry an addition all-around white light located as close as practicable to the mid-point of the group,
• notwithstanding paragraph (c), in the waters of the Great Lakes Basin, a power-driven vessel, when pushing ahead or towing alongside, shall exhibit two towing lights in a vertical line instead of the sternlight prescribed in paragraph (c),
• in the waters of the Great Lakes Basin, a special flashing light shall be exhibited at the forward end of a vessel or vessels being pushed ahead, in addition to the lights prescribed in paragraph (f).
• for the purpose of paragraph (h), within the canadian waters of a roadstead, harbour, river, lake or inland waterway, where it is impracticable for a log tow to comply with paragraph (g), the log tow shall exhibit;
  i. if it is less than 25 meters in breadth, one all-around white light at or near the forward end and one at or near the after end,
  ii. if it is less than 25 meters in breadth and exceeds 100 meters in length, one additional all-around white light at or near the mid-point of the length,
  iii. if it is 25 meters or more in breadth, a total of four all-around white lights, one at or near each corner, and,
  iv. if it is 25 meters or more in breadth and exceeds 100 meters in length, an additional all-around white light at or near the mid-point of each side of the length.

rule 24 is one of the longest rules in the canadian modifications to the collision regulations, with 13 sections, each containing multiple subsections and referencing other subheadings and previous rules. A vessel which is engaged in towing is also a power-driven vessel, so certain rules pertaining to the vessel itself from part 23 (like the length calling for an additional masthead light) apply here (see 24d). When viewing a vessel being towed from directly astern, it may not be possible to tell whether the tow is greater than 200 meters because the mastlights indicating this are not visible from the 'stern' arc of visibility- only the sternlight and towing light would be visible, in addition to any lights which are displayed on the tow itself. 24h provides that, if towing an object (partially submerged or otherwise) and it is not able to be lit as these rules call for, an effort will be made to light it to indicate its presence at the very least; and 24j further adds onto 24h and gives conditions for barges which are being towed. Within the great lakes basin, the requirements for lights are different and power driven vessels must display two towing lights in a line rather than the sternlight; in practice, this wouldn't look that different from a normal towing light configuration at the stern except that there would now be two yellow lights instead of a white and a yellow light. 24j surfaces often on the NS1 level examinations and should be noted with care.

(25) Sailing Vessels Underway and Vessels Under Oars:

• a sailing vessel underway shall exhibit;
  i. sidelights,
  ii. a sternlight
• in a sailing vessel of less than 20 metres in length the lights prescribed in paragraph (a) of this Rule may be combined in one lantern carried at or near the top of the mast where it can best be seen,
• a sailing vessel underway may, in addition to the lights prescribed in paragraph (a) of this Rule, exhibit at or near the top of the mast, where they can best be seen, two all-round lights in a vertical line, the upper being red and the lower green, but these lights shall not be exhibited in conjunction with the combined lantern permitted by paragraph (b) of this Rule,
• i. a sailing vessel of less than 7 metres in length shall, if practicable, exhibit the lights prescribed in paragraph (a) or (b) of this Rule, but if she does not, she shall have ready at hand an electric torch or lighted lantern showing a white light which shall be exhibited in sufficient time to prevent collision,
  ii. a vessel under oars may exhibit the lights prescribed in this Rule for sailing vessels, but if she does not, she shall have ready at hand an electric torch or lighted lantern showing a white light which shall be exhibited in sufficient time to prevent collision.
• a vessel proceeding under sail when also being propelled by machinery shall exhibit forward where it can best be seen a conical shape, apex downwards.
canadian modifications exist as follows....
• notwithstanding paragraph (e), in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, a vessel of less than 12 metres in length proceeding under sail when also being propelled by machinery is not required to exhibit a conical shape, apex downwards, but may do so.

It is of note that sailing vessels do not have a 'standard' masthead light. When a sailing vessel is exhibiting the conical day shape they are indicating that they have no more privilege than a power driven vessel (even if their sails are out); and at night a sailing vessel being propelled by machinery (even if sails are out) would exhibit the same lights as a power driven vessel. As provided in 25c, a sailing vessel may exhibit two all around lights, the upper red and the lower green- this is optional, and a sailing vessel is only required to display sidelights (which may be combined into one lantern) and a sternlight.

(26) Fishing Vessels:

• a vessel engaged in fishing, whether underway or at anchor, shall exhibit only the lights and shapes prescribed in this Rule.
• a vessel when engaged in trawling, by which is meant the dragging through the water of a dredge net or other apparatus used as a fishing appliance, shall exhibit;
  i. two all-round lights in a vertical line, the upper being green and the lower white, or a shape consisting of two cones with their apexes together in a vertical line one above the other,
  ii. a masthead light abaft of and higher than the all-round green light; a vessel of less than 50 metres in length shall not be obliged to exhibit such a light but may do so,
  iii. when making way through the water, in addition to the lights prescribed in this paragraph, sidelights and a sternlight.
• a vessel engaged in fishing, other than trawling, shall exhibit:
  i. two all-round lights in a vertical line, the upper being red and the lower white, or a shape consisting of two cones with their apexes together in a vertical line one above the other,
  ii. when there is outlying gear extending more than 150 metres horizontally from the vessel, an all-round white light or a cone apex upwards in the direction of the gear,
  iii. when making way through the water, in addition to the lights prescribed in this paragraph, sidelights and a sternlight.
• the additional signals described in Annex II apply to a vessel engaged in fishing in close proximity to other vessels engaged in fishing.
• a vessel when not engaged in fishing shall not exhibit the lights or shapes prescribed in this Rule, but only those prescribed for a vessel of her length.

A vessel not engaged in fishing (as in not having their nets or other fishing apparatus out) is a power driven vessel and must display lights as such. Notable in part 26a is that 'whether underway or at anchor' shall (must) exhibit the lights and shapes prescribed in rule 26 as long as they are fishing. The all-around lights prescribed in this rule must be exhibited when fishing, but the side and sternlights must only be used when making way through the water. Regardless of the length of the vessel, there are no additional masthead lights which are prescribed for vessels engaged in fishing (these circumstances change when they stop fishing). A fishing vessel with outlying gear must exhibit an all-around white light or conical dayshape with the apex (point) of the cone upwards in the direction of the fishing gear.

(27) Vessels not under Command or Restricted in their Ability to Maneouvre:

• a vessel not under command shall exhibit;
  i. two all-round red lights in a vertical line where they can best be seen,
  ii. two balls or similar shapes in a vertical line where they can best be seen,
  iii. when making way through the water, in addition to the lights prescribed in this paragraph, sidelights and a sternlight.
• a vessel restricted in her ability to manoeuvre, except a vessel engaged in mineclearance operations, shall exhibit;
  i. three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white,
  ii. three shapes in a vertical line where they can best be seen. The highest and lowest of these shapes shall be balls and the middle one a diamond,
  iii. when making way through the water, a masthead light or lights, sidelights and a sternlight, in addition to the lights prescribed in subparagraph (i),
  iv. when at anchor, in addition to the lights or shapes prescribed in subparagraphs (i) and (ii), the light, lights or shape prescribed in Rule 30,
• a power-driven vessel engaged in a towing operation such as severely restricts the towing vessel and her tow in their ability to deviate from their course shall, in addition to the lights or shapes prescribed in Rule 24(a), exhibit the lights or shapes prescribed in subparagraphs b(i) and (ii) of this rule,
• a vessel engaged in dredging or underwater operations, when restricted in her ability to manoeuvre, shall exhibit the lights and shapes prescribed in subparagraphs b(i), (ii) and (iii) of this Rule and shall in addition, when an obstruction exists, exhibit;
  i. two all-round red lights or two balls in a vertical line to indicate the side on which the obstruction exists,
  ii. two all-round green lights or two diamonds in a vertical line to indicate the side on which another vessel may pass,
  iii. when at anchor the lights or shapes prescribed in this paragraph instead of the lights or shape prescribed in Rule 30,
• whenever the size of a vessel engaged in diving operations makes it impracticable to exhibit all lights and shapes prescribed in paragraph (d) of this Rule, the following shall be exhibited;
  i. three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white,
  ii. a rigid replica of the International Code flag “A” not less than one metre in height. Measures shall be taken to ensure its all-round visibility,
• a vessel engaged in mineclearance operations shall, in addition to the lights prescribed for a power-driven vessel in Rule 23 or to the lights or shape prescribed for a vessel at anchor in Rule 30 as appropriate, exhibit three all-round green lights or three balls. One of these lights or shapes shall be exhibited near the foremast head and one at each end of the fore yard. These lights or shapes indicate that it is dangerous for another vessel to approach within 1 000 metres of the mineclearance vessel.
• vessels of less than 12 metres in length, except those engaged in diving operations, shall not be required to exhibit the lights and shapes prescribed in this Rule.
• The signals prescribed in this Rule are not signals of vessels in distress and requiring assistance. Such signals are contained in Annex IV.

Vessels which are 'not under command' do not display a mast head light or lights, and only display sidelights when making way through the water. A vessel restricted in her ability to maneouvre is restricted by the nature of her work and must display the appropriate all-around lights to indicate this; and in addition must display sidelights, a sternlight and any masthead lights if making way through the water. Dredging and vessels conducting underwater operations have special signals to indicate their special status to traffic; the side with two diamonds, or that has two green lights indicates the side which is safe to pass (though at great distances, it may be permissable to pass on either side of the vessel). In order to be considered 'not under command' a vessel must be underway; however with vessels 'restricted in their ability to maneouvre' even a vessel at anchor can hold this status. A mine-clearance ship does not have to exhibit the same symbols as other RAM vessels, in order to help differentiate this status and better convey the hazard of coming too close to this type of vessel.

(28) Vessels Constrained by their Draught:

• a vessel constrained by her draught may, in addition to the lights prescribed for power-driven vessels in Rule 23, exhibit where they can best be seen three all-round red lights in a vertical line, or a cylinder.
canadian modifications exist as follows...
• notwithstanding paragraph (a), in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, no vessel shall exhibit three all-round red lights in a vertical line or a cylinder.

In canada, there is no such status as 'constrained by their draught', but this status exists internationally.

(29) Pilot Vessels:

• a vessel engaged on pilotage duty shall exhibit;
  i. at or near the masthead, two all-round lights in a vertical line, the upper being white and the lower red,
  ii. when underway, in addition, sidelights and a sternlight,
  iii. when at anchor, in addition to the lights prescribed in subparagraph (i), the light, lights or shape prescribed in Rule 30 for vessels at anchor.
• a pilot vessel when not engaged on pilotage duty shall exhibit the lights or shapes prescribed for a similar vessel of her length.

When not on active duty, a pilot boat will just display lights as if she were an ordinary power-driven vessel.

(30) Anchored Vessels and Vessels Aground:

• a vessel at anchor shall exhibit where it can best be seen:
  i. in the fore part, an all-round white light or one ball,
  ii. at or near the stern and at a lower level than the light prescribed in subparagraph (i), an all-round white light.
• a vessel of less than 50 metres in length may exhibit an all-round white light where it can best be seen instead of the lights prescribed in paragraph (a) of this Rule.
• a vessel at anchor may, and a vessel of 100 metres and more in length shall, also use the available working or equivalent lights to illuminate her decks
• a vessel aground shall exhibit the lights prescribed in paragraph (a) or (b) of this Rule and in addition, where they can best be seen:
  i. two all-around red lights in a vertical line,
  ii. three balls in a vertical line,
• a vessel of less than seven metres in length, when at anchor, not in or near a narrow channel, fairway or anchorage, or where other vessels normally navigate, shall not be required to exhibit the lights or shape prescribed in paragraphs (a) and (b) of this Rule.
• A vessel of less than 12 metres in length, when aground, shall not be required to exhibit the lights or shapes prescribed in subparagraphs (d)(i) and (ii) of this Rule.
canadian modifications exist as follows...
• in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, instead of exhibiting the lights prescribed by paragraphs (a) to (c) of this Rule, a barge or an inconspicuous, partly submerged vessel or object may, when at anchor, exhibit;
  i. in the case of a barge, those prescribed by Rule 24(j), and
  ii. in the case of an inconspicuous, partly submerged vessel or object, those prescribed by Rule 24(g).
• notwithstanding this Rule, in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, a barge or an inconspicuous, partly submerged vessel or object, when at anchor, is not required to exhibit any light while located within a recognized mooring, storage or booming area that is not an area in or near a narrow channel or fairway or where other vessels normally navigate.

The anchoring rules are very straightforward and are laid out by vessel size; a vessel greater than 50 meters must exhibit an additional light on the stern when at anchor (the intention of which is to just mark the forward and aft ends of the vessel that may otherwise be obscured by darkness). Vessels of greater than 100 meters in length must illuminate their outer decks (and smaller vessels may also do the same). A vessel aground must exhibit the symbols as if she was at anchor, and in addition to this must also display two all around lights in a vertical line (similarily to if she was NUC, as they may be considered comparable statuses) or three black balls in a vertical line. The canadian modifications direct barge and other towing-related objects to rule 24, where they are covered there. If a barge is anchored within a recogized mooring/storage/boom area it is authorized to not exhibit any lights at all so long as it is not in a narrow channel or fairway, or an area where other vessels normally navigate (this information has notably appeared on NS1 examinations).

(31) Seaplanes:

where it is impracticable for a seaplane or a WIG craft to exhibit lights and shapes of the characteristics or in the positions prescribed in the Rules of this Part she shall exhibit lights and shapes as closely similar in characteristics and position as is possible.

As noted earlier in the regulations, seaplanes when operating on the water are required to keep clear of all vessels (rule 18e) but if risk of collision exists must comply with the rules of the road. Light configurations on seaplanes and WIG craft may vary depending on the design of the craft.

(32) Definitions:

• the word 'whistle' means any sound signalling appliance capable of producing the prescibed blasts and which complies witht he specifications in Annex III to these regulations,
• the term 'short blast' means a blast of about one second's duration,
• the term 'prolonged blast' means a blast of from four to six seconds' duration,

A short blast is about second long, and a prolonged blast is 4-6 seconds; both of these are emulating or are comparable to morse code signal lengths.

(33) Equipment for Sound Signals:

• a vessel of 12 metres or more in length shall be provided with a whistle, a vessel of 20 metres or more in length shall be provided with a bell in addition to a whistle, and a vessel of 100 metres or more in length shall, in addition, be provided with a gong, the tone and sound of which cannot be confused with that of the bell. The whistle, bell and gong shall comply with the specification in Annex III to these Regulations. The bell or gong or both may be replaced by other equipment having the same respective sound characteristics, provided that manual sounding of the prescribed signals shall always be possible,
• a vessel of less than 12 metres in length shall not be obliged to carry the sound signalling appliances prescribed in paragraph (a) of this Rule but if she does not, she shall be provided with some other means of making an efficient sound signal,
Canadian modifications exist as follows...
• notwithstanding paragraph (b), in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, a vessel shall carry the sound signalling appliances prescribed in paragraph (a) for a vessel of 12 metres or more in length, if it is,
  i. less than 12 metres in length,
  ii. ordinarily used for the purpose of pushing or pulling any floating object, and,
  iii. not employed solely in yarding or warping operations.

The fairly standard vessel sizing makes a return in rule 34 (12m, 20m, and 100m), though the wording should be paid careful attention to as it refers to vessels 100 meters or more (meaning the previous rules effect vessels of 20-99 meters long). A vessel which is less than 12 meters is permitted to use even a simple airhorn for sound signalling.

(34) Maneouvering and Warning Signals:

• when vessels are in sight of one another, a power-driven vessel underway, when manoeuvring as authorized or required by these rules, shall indicate that manoeuvre by the following signals on her whistle:
  - one short blast to mean “I am altering my course to starboard”,
  - two short blasts to mean “I am altering my course to port”,
  - three short blasts to mean “I am operating astern propulsion”.
• any vessel may supplement the whistle signals prescribed in paragraph (a) of this Rule by light signals, repeated as appropriate, whilst the manoeuvre is being carried out:
  i. these light signals shall have the following significance;
  - one flash to mean “I am altering my course to starboard”,
  - two flashes to mean “I am altering my course to port”,
  - three flashes to mean “I am operating astern propulsion”,
  ii. the duration of each flash shall be about one second, the interval between flashes shall be about one second, and the interval between successive signals shall be not less than 10 seconds,
  iii. the light used for this signal shall, if fitted, be an all-round white light, visible at a minimum range of 5 miles, and shall comply with the provisions of Annex I.
• when in sight of one another in a narrow channel or fairway:
  i. a vessel intending to overtake another shall in compliance with Rule 9(e)(i) indicate her intention by the following signals on her whistle:
  - two prolonged blasts followed by one short blast to mean “I intend to overtake you on your starboard side”,
  - two prolonged blasts followed by two short blasts to mean “I intend to overtake you on your port side”,
  ii. the vessel about to be overtaken when acting in accordance with Rule 9(e)(i) shall indicate her agreement by the following signal on her whistle;
  - one prolonged blast, one short, one prolonged and one short blast, in that order.
• when vessels in sight of one another are approaching each other and from any cause either vessel fails to understand the intentions or actions of the other, or is in doubt whether sufficient action is being taken by the other to avoid collision, the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. Such signal may be supplemented by a light signal of at least five short and rapid flashes.
• a vessel nearing a bend or an area of a channel or fairway where other vessels may be obscured by an intervening obstruction shall sound one prolonged blast. Such signal shall be answered with a prolonged blast by any approaching vessel that may be within hearing around the bend or behind the intervening obstruction.
• if whistles are fitted on a vessel at a distance apart of more than 100 metres, one whistle only shall be used for giving manoeuvring and warning signals.
Canadian modifications exist as follows...
• notwithstanding paragraph (a), in the waters of the Great Lakes Basin, when power-driven vessels are in sight of one another and meeting or crossing at a distance within half a mile of each other, each vessel underway, when manoeuvring as authorized or required by these rules
  i. shall indicate that manoeuvre as by the following signals on her whistle;
  - one short blast to mean “I intend to leave you on my port side”,
  - two short blasts to mean “I intend to leave you on my starboard side”, and
  - three short blasts to mean “I am operating astern propulsion”, and
  ii. shall, upon hearing the one or two blast signal, referred to in subparagraph (i), of the other vessel indicate her agreement by sounding the same whistle signal and taking the steps necessary to effect a safe passing. If, however, for any cause, a vessel on hearing a one or two blast signal referred to in subparagraph (i) doubts the safety of the proposed manoeuvre, she shall sound the signal specified in paragraph (d) and each vessel shall take appropriate precautionary action until a safe passing agreement is made.
• notwithstanding paragraph (b), in the waters of the Great Lakes Basin, a vessel may supplement the whistle signals prescribed in paragraph (g) by light signals
  i. that have the following significance:
  - one flash to mean “I intend to leave you on my port side”,
  - two flashes to mean “I intend to leave you on my starboard side”,
  - three flashes to mean “I am operating astern propulsion”, and
  ii. the duration of which shall be about one second for each flash.
• the light used for a signal referred to in paragraph (h), shall, if fitted, be one all-round white or yellow light, visible at a minimum range of two miles, synchronized with the whistle signal referred to in paragraph (g), and shall comply with section 12 of Annex I.
• notwithstanding paragraph (c), in the waters of the Great Lakes Basin, when power-driven vessels are in sight of one another in a narrow channel or fairway,
  i. the vessel intending to overtake another shall, in compliance with Rule 9(i), indicate her intention by the following signals on her whistle:
  - one short blast to mean “I intend to overtake you on your starboard side”,
  - two short blasts to mean “I intend to overtake you on your port side”,
  ii. the vessel about to be overtaken when acting in accordance with Rule 9(i) shall, if in agreement, sound the same signal as given by the other vessel. If in doubt, she shall sound the signal prescribed in paragraph (d)
• In the Canadian waters of a roadstead, harbour, river, lake or inland waterway, a power-driven vessel of 12 metres or more in length that is leaving a dock or berth shall give a signal of one prolonged blast unless
  i. the vessel is a ferry making a scheduled departure from a dock or berth from which more than six daily scheduled departures are made,
  ii. the visibility is not less than 3 miles, and
  iii. the master of the ferry has used all available means appropriate to the prevailing circumstances and conditions to determine if the signal is needed for a safe departure and has determined that it is not.
• notwithstanding this Rule and Rule 9, if positive mutual identification of the vessels has been made in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, a vessel may use a bridge-to-bridge radiotelephone instead of the prescribed whistle signals to reach agreement in a meeting, crossing or overtaking situation. If agreement is not reached, then whistle signals shall be exchanged in a timely manner and shall prevail.

Rule 34a lays out multiple perimeters which vessels must pass in order for the rule to apply; she must be a power-driven vessel, must be underway, and must be in sight of another vessel. Signals prescribed in 34a are 'signals of action' which inform the other vessel of your actions, not just of your intention to act (this distinction is important when compared against the signals of intent prescribed in 9e, or 34g). Light signals may be used to supplement the whistle signals, but this is not required, and a 'gap' of 10 seconds between signals must be allowed. In channels around a bend or where view may be obscured vessels must give one prolonged blast, which nearby vessels must 'echo' back by repeating the same signal if heard. The signal prescribed for agreement is the morse code for 'charlie' (-.-.) from the International Code of Signals (meaning yes/agreement), and the signal for confusion or danger is five short blasts (.....), which does not coincide with any morse signals but is quite universally regarded and recognized as the warning signal. 34g gives different signals than the ones prescribed in 34a, which similarily must pass multiple 'tests' in order to be applicable; vessels must be located within the Great Lakes Basin, in sight of one another, and with a closest point of approach (CPA) within half a mile of one another. The signals prescribed in 34g, like 34a, are signals of intention to act rather than of action. The light signals in 34h, which may supplement (be added onto) the sound signals, have a minimum visibility of 2 miles and may be given with either an all around yellow or all around white light; they must also be synchronized with the whistle sound signals.

(35) Sound Signals in Restricted Visibility:

In or near an area of restricted visibility, whether by day or night, the signals prescribed in this Rule shall be used as follows:
• a power-driven vessel making way through the water shall sound at intervals of not more than two minutes one prolonged blast.
• a power-driven vessel underway but stopped and making no way through the water shall sound at intervals of not more than two minutes two prolonged blasts in succession with an interval of about two seconds between them.
• a vessel not under command, a vessel restricted in her ability to manoeuvre, a vessel constrained by her draught, a sailing vessel, a vessel engaged in fishing and a vessel engaged in towing or pushing another vessel shall, instead of the signals prescribed in paragraph (a) or (b) of this Rule, sound at intervals of not more than two minutes three blasts in succession, namely one prolonged followed by two short blasts.
• a vessel engaged in fishing, when at anchor, and a vessel restricted in her ability to manoeuvre when carrying out her work at anchor, shall instead of the signals prescribed in paragraph (g) of this Rule sound the signal prescribed in paragraph (c) of this Rule.
• a vessel towed or if more than one vessel is towed the last vessel of the tow, if manned, shall at intervals of not more than two minutes sound four blasts in succession, namely one prolonged followed by three short blasts. When practicable, this signal shall be made immediately after the signal made by the towing vessel.
• when a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit they shall be regarded as a power-driven vessel and shall give the signals prescribed in paragraph (a) or (b) of this Rule.
• a vessel at anchor shall at intervals of not more than one minute ring the bell rapidly for about five seconds. In a vessel of 100 metres or more in length the bell shall be sounded in the forepart of the vessel and immediately after the ringing of the bell the gong shall be sounded rapidly for about five seconds in the after part of the vessel. A vessel at anchor may in addition sound three blasts in succession, namely one short, one prolonged and one short blast, to give warning of her position and of the possibility of collision to an approaching vessel.
• a vessel aground shall give the bell signal and if required the gong signal prescribed in paragraph (g) of this Rule and shall, in addition, give three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell. A vessel aground may in addition sound an appropriate whistle signal.
• a vessel of 12 metres or more but less than 20 metres in length shall not be obliged to give the bell signals prescribed in paragraphs (g) and (h) of this Rule. However, if she does not, she shall make some other efficient sound signal at intervals of not more than 2 minutes.
• a vessel of less than 12 metres in length shall not be obliged to give the above mentioned signals but, if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.
• a pilot vessel when engaged on pilotage duty may in addition to the signals prescribed in paragraphs (a), (b) or (g) of this Rule sound an identity signal consisting of four short blasts.
Canadian modifications exist for this rule as follows...
• notwithstanding paragraph (j), in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, a vessel shall sound the signals prescribed for a vessel of 12 metres or more in length if it is
  i. less than 12 metres in length,
  ii. ordinarily used for the purpose of pushing or pulling any floating object, and
  iii. not located within a recognized mooring, storage or booming area.

There are a lot of sound signals which are covered under this rule; more complex signals tend to build upon the most basic fog signal for power-driven vessels. As a general rule, no signal will ever sound at a frequency of more than 2 minutes, and each signal begins at least one prolonged blast (to differentiate, as all of the standard non-fishing manoeuvering signals begin with one short blast). There is another very distinct line drawn between vessels underway and making way and vessels underway but not making way, both of which are in reference to vessels which are not anchored, aground, or tied to the dock but are either making way (engine propulsion, wind pushing sails) or not (drifting through the water).

(36) Signals to Attract Attention:

if necessary to attract the attention of another vessel any vessel may make light or sound signals that cannot be mistaken for any signal authorized elsewhere in these Rules, or may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel. Any light to attract the attention of another vessel shall be such that it cannot be mistaken for any aid to navigation. For the purpose of this Rule the use of high intensity intermittant or revolving lights, such as strobe lights, shall be avoided.

(37) Distress Signals:

when a vessel is in distress and requires assistance she shall use or exhibit the signals described in Annex IV.

(38) Exemptions:

Any vessel (or class of vessels) provided that she complies with the requirements of the International Regulations for Preventing Collisions at Sea, 1960, the keel of which is laid or which is at a corresponding stage of construction before the entry into force of these Regulations is exempted from compliance therewith as follows:
• the installation of lights with ranges prescribed in Rule 22, until four years after the date of entry into force of these Regulations.
• the installation of lights with colour specifications as prescribed in section 7 of Annex I to these Regulations, until four years after the date of entry into force of these Regulations.
• the repositioning of lights as a result of conversion from Imperial to metric units and rounding off measurement figures, permanent exemption.
• i. the repositioning of masthead lights on vessels of less than 150 metres in length, resulting from the prescriptions of section 3(a) of Annex I, permanent exemption.
  ii. the repositioning of masthead lights on vessels of 150 metres or more in length, resulting from the prescriptions of section 3(a) of Annex I, until nine years after the date of entry into force of these Regulations.
• the repositioning of masthead lights resulting from the prescriptions of section 2(b) of Annex I, until nine years after the date of entry into force of these Regulations.
• the repositioning of sidelights resulting from the prescriptions of sections 2(g) and 3(b) of Annex I, until nine years after the date of entry into force of these Regulations
• the requirements for sound signal appliances prescribed in Annex III, until nine years after the date of entry into force of these Regulations.
• the repositioning of all-round lights resulting from the prescription of section 9(b) of Annex I, permanent exemption.
Canadian modifications for this rule exist as follows...
• for the purposes of paragraphs (d), (e), (f) and (g), the nine years referred to therein shall be considered to commence on July 15, 1977.
• notwithstanding paragraph (i), the nine years referred to in paragraphs (d), (e), (f) and (g) shall be considered to commence on March 1, 1983 for vessels exclusively engaged in inland voyages.

The following rules (39-46) are exclusive to the Canadian modifications to the COLREGS

(39) Special Signals for Dangerous Goods:

In the Canadian waters of a roadstead, harbour, river, lake or inland waterway, a vessel that is taking in, discharging or carrying dangerous goods shall,
• when not underway, exhibit where it can best be seen, an all-round red light or the International Code flag “B”; and
• when underway, exhibit where it can best be seen, the International Code flag “B” but not an all-round red light.

Very simple rule; a vessel carrying dangerous goods will always fly the red 'Bravo' flag, but only when not underway is able to exhibit an all around red light. Most vessels to which this rule applies will just always have their 'B' flag flown. It is important for the all-around red light, if exhibited, to not be displayed in a way in which it may be mistaken for another light, or falsely taken as part of a combination of other lights displayed.

(40) Radar Reflectors:

• subject to paragraph (b), a vessel that is less than 20 metres in length or is constructed primarily of non-metallic materials shall, if practicable, be equipped with a radar reflector or other means to enable the vessel’s detection by other vessels navigating by radar at 3 GHz or 9 GHz.
• Paragraph (a) does not apply where
  i. a vessel operates in limited traffic conditions, daylight, and favourable environmental conditions and where compliance is not essential for the safety of the vessel, or
  ii. the small size of the vessel or its operation away from radar navigation makes compliance impracticable.
• the radar reflector or other means to enable detection prescribed in paragraph (a) shall, to the extent practicable, meet the requirements of
  i. sections 3 to 5 of the Annex to Resolution A.384(X), made by the Organization and as amended from time to time, if fitted before July 1, 2005,
  ii. sections 3 to 5 of the Annex to Resolution MSC.164(78), made by the Organization and as amended from time to time, if fitted on or after July 1, 2005, or
  iii. other performance standards that the Minister determines provide a level of safety that is equivalent to or higher than that of those standards.
• for the purpose of interpreting a document incorporated by reference into this Rule, “should” shall be read to mean “shall” and recommendations shall be mandatory.

The key part to this section is the mention of either a vessel which is less than 20 meters in length (constructed with any materials) or is constructed with non-metallic materials (wood). The radar reflector should not be painted black so as to avoid confusion with any day shape. There are two kinds of radar reflectors; 'active' and 'passive', of which 'active' transponders are electronic and enhance the signal they recieve before reflecting it; whereas 'passive' reflectors just reflect back the radar wave.

(41) Transponders:

• no vessel, except a vessel in distress, shall use a transponder that can transmit radar responder signals or radar beacon signals in the 3- or 10-centimetre marine radar bands.
• notwithstanding paragraph (a), an exploration or exploitation vessel may use such a transponder if authorized to do so under this Rule and the transponder is used in a manner that does not compromise the safety of navigation.
• the Minister shall authorize the use of a transponder if it will be used in a manner that will not interfere with or degrade the use of radar in navigation, having regard to factors such as
  i. the proximity of other transponders and the distinctiveness of their signals,
  ii. the frequency, range and power of the transponder, and
  iii. the marine radar band to be used.

Use of the SART is an internationally recognized signal for distress, and will only respond to a 3cm (X-band) radar. If the use of radar transponders was not subject to regulation and control then it is concievable that when navigating in areas of high traffic, there may be numerous transponder beacons which would crowd the radar screens and interfere with navigation.

(42) Additional Requirements for Exploration or Exploitation Vessels:

• an exploration or exploitation vessel shall display identification panels bearing the name, identification letters or numerals of the vessel so that at least one panel is visible in any direction.
• the name, identification letters or numerals referred to in paragraph (a) shall be
  i. black,
  ii. not less than one meter in height,
  iii. displayed on a yellow background, and,
  iv. easily visible in daylight and at night by the use of illumination or retro-reflecting material.
• subject to paragraph (h), an exploration or exploitation vessel, when stationary and engaged in drilling or production operations, shall, in lieu of the lights or shapes required by these Rules, exhibit where it can best be seen from any direction a white light or a series of white lights located at an equal height above the water and operating in unison, which light or lights shall
  i. flash the morse letter “U” at intervals of not more than 15 seconds,
  ii. be installed at a height above the water of not less than six metres and not more than 30 metres so that at least one light shall remain visible to within 15 metres of the vessel,
  iii. be visible all round the horizon at a nominal range of 15 miles,
  iv. be powered by a reliable power source,
  v. be equipped with an auxiliary power source, and
  vi. be exhibited from 15 minutes before sunset until sunrise and at all times when the visibility in any direction is two miles or less.
• the horizontal and vertical extremities of an exploration or exploitation vessel that is stationary and engaged in drilling or production operations shall be adequately marked in compliance with the requirements set out in Transport Canada Standards Obstruction Markings (2nd ed.), 1987, TP 382, as amended from time to time
• An exploration or exploitation vessel, when stationary and engaged in drilling or production operations, shall be equipped with a sound-signalling appliance that
  i. is powered by a reliable power source,
  ii. is provided with an auxiliary power source,
  iii. when operating, emits a rhythmic blast corresponding to the Morse letter “U” every 30 seconds,
  iv. has its maximum intensity at a frequency between 100 and 1 000 Hertz,
  v. has a usual range of at least two miles,
  vi. is installed at a height above the water of not less than six metres and not more than 30 metres, and
  vii. is so placed that the sound emitted is audible, when there is no wind, throughout the required range in all directions in a horizontal plane from the vessel.
• an exploration or exploitation vessel, when stationary and engaged in drilling or production operations, shall, whenever the visibility in any direction is two miles or less, operate the sound-signalling appliance described in paragraph (e) in lieu of the sound signal described in Rule 35.
• an exploration or exploitation vessel shall comply with the relevant technical requirements set out in sections 2.3 and 2.4 of, and Appendix 1 to, the IALA’s publication Recommendations for the marking of offshore structures, as amended from time to time, and the nominal range of lights shall be computed in accordance with Appendix II of the IALA’s 1967 publication Recommendations for the notation of luminous intensity and range of lights.
• for the purposes of this Rule, wherever the word “Authority” appears in a document incorporated by reference, it shall be read as “Minister”.
• in the Canadian waters of the Great Lakes Basin, the white light or series of white lights exhibited by an exploration or exploitation vessel when stationary and engaged in drilling or production operations shall have a range of visibility of between eight and fifteen miles.

(43) Safety Zones Around Exploration or Exploitation Vessels:

• for the purpose of this Rule, with respect to an exploration or exploitation vessel that is in position for the purpose of exploring or exploiting the non-living natural resources of the sea bed, a safety zone is the area that extends from the outer extremities of the exploration or exploitation vessel to the greater of
  i. 500 metres in all directions, and
  ii. 50 metres beyond the boundaries of the anchor pattern of the vessel.
• the Minister may establish a safety zone greater than the safety zone referred to in paragraph (a) if it is reasonably related to the nature and function of the exploration or exploitation vessel and is necessary to ensure navigational safety.
• no vessel shall navigate within a safety zone.
• Paragraph (c) does not apply to a vessel that
  i. is in distress,
  ii. is attempting to save life or provide assistance to a vessel in distress,
  iii. is operated by or on behalf of the state having jurisdiction over the exploration or exploitation operations, or
  iv. has received permission from the person in charge of the exploration or exploitation vessel to enter the safety zone around that vessel.

This rule is largely in reference to offshore drilling and operations surrounding offshore exploitation work. The minimum safety zone around an exploitation vessel is either 500 meters, or 50 meters beyond the anchor pattern of the vessel (a circular radius around the vessel), whichever is the larger value

(44) Ocean Data Acquisition Systems (ODAS):

• Every Canadian ODAS shall clearly display its identification number on an exterior surface where it can be clearly seen and, if practicable, shall display the name and address of the owner of the ODAS.
• Subject to paragraph (f), every ODAS shall be constructed or fitted with a radar reflector, or other means, that has a radar response that at least meets the requirements set out in Rule 40.
• Every ODAS that is designed to operate while floating with part of its structure extending above the water shall
  i. be coloured yellow,
  ii. have a shape that cannot be confused with the shape of a navigational mark, and
  iii. where technically practicable,
  A) have a topmark consisting of a yellow “X” shape,
  B) exhibit a yellow light visible at a minimum range of five miles that gives a group of five flashes every 20 seconds, and
  C) be equipped with an appliance that emits a sound signal at intervals of not more than two minutes, which sound signal cannot be confused with any other signal prescribed by these Rules or with the sound signal of any aid to navigation in the vicinity of the ODAS.
• Subject to paragraph (f), every ODAS designed to operate under water, other than an ODAS referred to in paragraph (e), shall
  i. be escorted by a surface vessel that gives warning of the presence of the ODAS in accordance with Rule 27, or
  ii. have tethered to it a surface float that is marked, provides the radar response, is lighted and sounds the signals specified in paragraphs (a) to (c).
• Every ODAS designed to operate when resting on the bottom of a sea, lake or river with part of its structure extending above the water shall be marked, exhibit lights and shapes, and sound signals in the same manner as an exploration or exploitation vessel.
• Paragraphs (b) and (d) do not apply to an ODAS where
  i. the Minister has determined that the ODAS does not constitute a potential danger to navigation by reason of
  A) its size, material, construction, area or method of operation,
  B) the nature and condition of the waters in the area of operation of the ODAS, and
  C) the use that is or might reasonably be expected to be made of those waters, and
  ii. the Minister has given the owner of the ODAS notice in writing of that determination.

(45) Blue Flashing Light:

• Any government vessel or any vessel that is owned or operated by a harbour, river, county or municipal police force may exhibit as an identification signal a blue flashing light when the vessel
  i. is providing assistance in any waters to any vessel or other craft, aircraft or person that is threatened by grave and imminent danger and requires immediate assistance, or
  ii. is engaged in law enforcement duties in Canadian waters.
• Any vessel operated by the Canadian Coast Guard Auxiliary may exhibit a blue flashing light as an identification signal when the vessel participates, at the request of the Canadian Coast Guard, in search and rescue operations.
• A vessel referred to in paragraph (a) or (b) that exhibits a blue flashing light as an identification signal is not relieved from the obligation to comply with the Steering and Sailing Rules set out in Part B.

Blue flashing lights, which are not used internationally and exist within the Canadian modifications to the colregs, are always associated with the police and government vessels. No other vessels use blue lights or are permitted the use of blue lights.

(46) Alternate System of Navigation Lights:

• For the purpose of this Rule, “alternate system of navigation lights” means a backup system that includes masthead lights, sidelights, a sternlight and the lights prescribed in Rule 30 for vessels at anchor.
• This Rule does not apply to
  i. vessels that are less than 15 metres in length,
  ii. cable ferries, or
  iii. pleasure craft.
• A Canadian vessel required by Part C to exhibit lights shall be fitted with an alternate system of navigation lights.
• In the case of vessels built before January 1, 1991, that have a gross tonnage of less than 500, the alternate system of navigation lights may consist of oil or electronic lanterns.
• If it is impracticable for a vessel or object being towed or pushed to comply with paragraph (c), spare lights shall be readily available so that the vessel or object maintains compliance with Part C.
• The alternate system of navigation lights shall be supplied by the main source of electric power and the emergency source of electric power that are referred to in section 15 of Annex I, unless otherwise provided by paragraph (g).
• In the case of vessels built before January 1, 1991, having a gross tonnage of less than 500, the alternate system of navigation lights shall be supplied by
  i. the vessel’s emergency source of electric power, or
  ii. in the case of oil or electronic lanterns, power of a capacity sufficient for the duration of the intended voyage.
• Lights using a flame shall not be used as the alternate system of navigation lights on any vessel carrying, towing or pushing cargo that is volatile or explosive.

Of note with this rule is that it does not apply to vessels less than 15 meters in length (0m-14.999m), pleasurecraft, or cable ferries. This rule is in reference to the carriage of backup lights to assure compliance with the rules regarding the display of lights onboard. 46h mentions that flames are not to be used in the event, as they can easily give the wrong impression and be interpreted as a signal for distress (among other things). The key year to remember here is 1991, which determines whether a vessel may be allowed to have non-electric lights.

(A1.1) Definitions:

• The term height above the hull means height above the uppermost continuous deck. This height shall be measured from the position vertically beneath the location of the light.
canadian modifications exist as follows...
• The term practical cut-off means the point on an arc around a source of light at which the intensity of the light is reduced as follows:
  i. for vessels of less than 20 metres in length, where the intensity is reduced to 67 per cent of the minimum required intensity within three or five degrees as appropriate, outside the horizontal sectors referred to in section 9 of this Annex and described in Rule 21, practical cut-off occurs at the point at which the intensity is reduced to 10 per cent of the minimum required intensity within 20 degrees outside the horizontal sectors referred to in section 9 of this Annex and described in Rule 21,
  ii. for vessels of 20 metres or more in length, practical cut-off occurs at the point at which the intensity is reduced to 12.5 per cent of the minimum required intensity within three or five degrees, as appropriate, outside the horizontal sectors referred to in section 9 of this Annex and described in Rule 21

(A1.2) Vertical Positioning and Spacing of Lights:

• On a power-driven vessel of 20 metres or more in length the masthead lights shall be placed as follows:
  i. the forward masthead light, or if only one masthead light is carried, then that light, at a height above the hull of not less than six metres, and, if the breadth of the vessel exceeds six metres, then at a height above the hull not less than such breadth, so however that the light need not be placed at a greater height above the hull than 12 metres,
  ii. when two masthead lights are carried the after one shall be at least 4.5 metres vertically higher than the forward one.
• The vertical separation of masthead lights of power-driven vessels shall be such that in all normal conditions of trim the after light will be seen over and separate from the forward light at a distance of 1 000 metres from the stem when viewed from sea level.
• The masthead light of a power-driven vessel of 12 metres but less than 20 metres in length shall be placed at a height above the gunwale of not less than 2.5 metres.
• A power-driven vessel of less than 12 metres in length may carry the uppermost light at a height of less than 2.5 metres above the gunwale.
  i. where a masthead light is carried in addition to sidelights and a sternlight or where the all-round light described in subparagraph (d)(i) of Rule 23 is carried in addition to sidelights, the masthead light or the all-round light shall be carried at least one metre higher than the sidelights.
• One of the two or three masthead lights prescribed for a power-driven vessel when engaged in towing or pushing another vessel shall be placed in the same position as either the forward masthead light or the after masthead light, provided that, if carried on the aftermast, the lowest after masthead light shall be at least 4.5 metres vertically higher than the forward masthead light.
• i. The masthead light or lights prescribed in Rule 23 (a) shall be so placed as to be above and clear of all other lights and obstructions except as described in subparagraph (ii).
  ii. When it is impracticable to carry the all-round lights prescribed by Rule 27 (b)(i) or Rule 28 below the masthead lights, they may be carried above the after masthead light(s) or vertically in between the forward masthead light(s) and after masthead light(s), provided that in the latter case the requirement of section 3(c) of this Annex shall be complied with.
• The sidelights of a power-driven vessel shall be placed at a height above the hull not greater than three-quarters of that of the forward masthead light. They shall not be so low as to be interfered with by deck lights.
• The sidelights, if in a combined lantern and carried on a power-driven vessel of less than 20 metres in length, shall be placed not less than one metre below the masthead light.
• When the Rules prescribe two or three lights to be carried in a vertical line, they shall be spaced as follows:
  i. on a vessel of 20 metres in length or more, such lights shall be spaced not less than two metres apart, and the lowest of these lights shall, except where a towing light is required, be placed at a height of not less than four metres above the hull,
  ii. on a vessel of less than 20 metres in length, the lights shall be spaced not less than one metre apart and the lowest of the lights shall, except where a towing light is required, be placed at a height of not less than two metres above the gunwale,
  iii. when three lights are carried they shall be equally spaced.
• The lower of the two all-round lights prescribed for a vessel when engaged in fishing shall be at a height above the sidelights not less than twice the distance between the two vertical lights.
• The forward anchor light prescribed in Rule 30 (a)(i), when two are carried, shall not be less than 4.5 metres above the after one. On a vessel of 50 metres or more in length this forward anchor light shall be placed at a height of not less than six metres above the hull.
Canadian modifications exist as follows...
• Notwithstanding paragraph (a), in the waters of the Great Lakes Basin, on a power-driven vessel of 20 metres or more in length the masthead lights may be placed as follows:
  i. the forward masthead light, or if only one masthead light is carried, then that light, at a height above the hull of not less than five metres, and, if the breadth of the vessel exceeds five metres, then at a height above the hull of not less than such breadth, but the light need not be placed at a greater height above the hull than eight metres,
  ii. where two masthead lights are carried, the after one shall be at least two metres vertically higher than the forward one.
• Notwithstanding paragraph (d), in the Canadian waters of a roadstead, harbour, river, lake or inland waterway, the masthead light or the all-round white light referred to in Rule 23(d), for a power-driven vessel of less than 12 metres in length shall be carried at least one metre higher than the sidelights.
• Notwithstanding paragraph (e), in the waters of the Great Lakes Basin, one of the two or three masthead lights prescribed for a power-driven vessel when engaged in towing or pushing another vessel shall be placed in the same position as the forward masthead light or the after masthead light, but where the light is carried on the aftermast the lowest after masthead light shall be at least two metres vertically higher than the forward masthead light.
• Notwithstanding paragraph (g), in the waters of the Great Lakes Basin, the sidelights of a power-driven vessel may be placed at least one metre lower than the forward masthead light but shall not be so low as to be interfered with by deck lights.
• Notwithstanding subparagraph (i)(i), in the waters of the Great Lakes Basin, where a vessel of 20 metres in length or more is required to carry two or three lights in a vertical line, these lights may be spaced not less than one metre apart, and the lowest of these lights shall, except where a towing light is required, be placed at a height of not less than four metres above the hull.
• The all-round white lights prescribed for an inconspicuous, partly submerged vessel or object or a barge in Rule 24 (g) and (j), respectively, shall be carried at the same height and shall be placed at a height of not less than two metres above the water.
• The vertical separation of masthead lights required by subparagraph (a)(ii) and paragraph (b) is illustrated in Appendix II to Standards for Navigation Lights, Shapes, Sound-Signalling Appliances, TP 1861, published by Transport Canada, as amended from time to time.

(A1.3) Horizontal Positioning and Spacing of Lights:

• When two masthead lights are prescribed for a power-driven vessel, the horizontal distance between them shall not be less than one-half of the length of the vessel but need not be more than 100 metres. The forward light shall be placed not more than one-quarter of the length of the vessel from the stem.
• On a power-driven vessel of 20 metres or more in length the sidelights shall not be placed in front of the forward masthead lights. They shall be placed at or near the side of the vessel.
• When the lights prescribed in Rule 27 (b)(i) or Rule 28 are placed vertically between the forward masthead light(s) and the after masthead light(s) these all-round lights shall be placed at a horizontal distance of not less than two metres from the fore and aft centreline of the vessel in the athwartship direction.
• When only one masthead light is prescribed for a power-driven vessel, that light shall be exhibited forward of amidships, except that a vessel of less than 20 m in length need not exhibit that light forward of amidships but shall exhibit it as far forward as is practicable.
Canadian modifications exist as follows...
• Notwithstanding paragraph (a), in the waters of the Great Lakes Basin, where two masthead lights are prescribed for a power-driven vessel,
  i. the horizontal distance between them shall be not less than one-quarter the length of the vessel but need not be more than 50 m, and
  ii. the forward light shall be placed not more than one-half the length of the vessel away from the stem.

(A1.4) Details of location of direction-indicating lights for fishing vessels, dredgers and vessels engaged in underwater operations:

• the light indicating the direction of the outlying gear from a vessel engaged in fishing as prescribed in Rule 26(c)(ii) shall be placed at a horizontal distance of not less than two metres and not more than six metres away from the two all-round red and white lights. This light shall be placed not higher than the all-round white light prescribed in Rule 26(c)(i) and not lower than the sidelights.
• The lights and shapes on a vessel engaged in dredging or underwater operations to indicate the obstructed side and/or the side on which it is safe to pass, as prescribed in Rule 27(d)(i) and (ii), shall be placed at the maximum practical horizontal distance, but in no case less than two metres, from the lights or shapes prescribed in Rule 27(b)(i) and (ii). In no case shall the upper of these lights or shapes be at a greater height than the lower of the three lights or shapes prescribed in Rule 27(b)(i) and (ii).

(A1.5) Screens for Sidelights

The sidelights of vessels of 20 metres or more in length shall be fitted with inboard screens painted matt black and shall meet the requirements of section 9 of this Annex. On vessels of less than 20 metres in length the sidelights, if necessary to meet the requirements of section 9 of this Annex, shall be fitted with inboard matt black screens. With a combined lantern, using a single vertical filament and a very narrow division between the green and red sections, external screens need not be fitted.

Canadian modifications- Screens for Lights Other than Sidelights

On power-driven vessels of less than 12 metres in length, constructed after July 31, 1983, the masthead light or the all-round light referred to in Rule 23(d), shall be screened to prevent direct illumination of the vessel forward of the operator’s position.

This comes up regularily on examinations.

(A1.6) Day Shapes :

• Shapes shall be black and of the following sizes:
  i. a ball shall have a diameter of not less than 0.6 metre,
  ii. a cone shall have a base diameter of not less than 0.6 metre and a height equal to its diameter,
  iii. a cylinder shall have a diameter of at least 0.6 metre and a height of twice its diameter,
  iv. a diamond shape shall consist of two cones as defined in subparagraph (ii) above having a common base.
• The vertical distance between shapes shall be at least 1.5 metres.
• In a vessel of less than 20 metres in length shapes of lesser dimensions but commensurate with the size of the vessel may be used and the distance apart may be correspondingly reduced.

This part of the annex comes up frequently in examinations and is important to remember.

(A1.7)-(A1.8) can be read here:
Sections 7 and 8 involve the technical color-code for each color of light, and calculations for determining the intensity of these lights. This content has historically not appeared in the NS1 examinations so I've not bothered to copy it into this page.

(A1.9) Horizontal Sectors:

• i. In the forward direction, sidelights as fitted on the vessel shall show the minimum required intensities. The intensities shall decrease to reach practical cut-off between one degree and three degrees outside the prescribed sectors.
  ii. For sternlights and masthead lights and at 22.5 degrees abaft the beam for sidelights, the minimum required intensities shall be maintained over the arc of the horizon up to five degrees within the limits of the sectors prescribed in Rule 21. From five degrees within the prescribed sectors the intensity may decrease by 50 per cent up to the prescribed limits; it shall decrease steadily to reach practical cut-off at not more than five degrees outside the prescribed sectors.
• i. All-round lights shall be so located as not to be obscured by masts, topmasts or structures within angular sectors of more than six degrees, except anchor lights prescribed in Rule 30, which need not be placed at an impracticable height above the hull.
  ii. If it is impracticable to comply with subparagraph (i) by exhibiting only one all-round light, two all-round lights shall be used suitably positioned or screened so that they appear, as far as practicable, as one light at a distance of one mile.
Canadian modifications exist as follows...
• Notwithstanding paragraph (b), in the waters of the Great Lakes Basin, the all-round white light or lights referred to in Rule 23(f) shall not be obscured.

(A1.10) Vertical Sectors:

• The vertical sectors of electric lights as fitted, with the exception of lights on sailing vessels underway, shall be such that
  i. at least the required minimum intensity is maintained at all angles from five degrees above to five degrees below the horizontal,
  ii. at least 60 per cent of the required minimum intensity is maintained from 7.5 degrees above to 7.5 degrees below the horizontal.
• In the case of sailing vessels underway, the vertical sectors of electric lights as fitted shall be such that
  i. at least the required minimum intensity is maintained at all angles from five degrees above to five degrees below the horizontal,
  ii. at least 50 per cent of the required minimum intensity is maintained from 25 degrees above to 25 degrees below the horizontal.
• In the case of lights other than electric these specifications shall be met as closely as possible.
Canadian modifications exist as follows...
• Where from any sufficient cause it is impracticable for an unmanned barge or log tow in Canadian waters of a roadstead, harbour, river, lake or inland waterway to exhibit lights that comply with the vertical sector requirements of paragraph (a), the lights on the unmanned barge or log tow need not comply with the vertical sector requirements but shall maintain the required minimum intensity on the horizontal.

(A1.12) Manoeuvring Light:

• Notwithstanding the provisions of paragraph 2(f) of this Annex the manoeuvring light described in Rule 34 (b) shall be placed in the same fore and aft vertical plane as the masthead light or lights and, where practicable, at a minimum height of two metres vertically above the forward masthead light, provided that it shall be carried not less than two metres vertically above or below the after masthead light. On a vessel where only one masthead light is carried the manoeuvring light, if fitted, shall be carried where it can best be seen, not less than two metres vertically apart from the masthead light.
Canadian modifications exist as follows...
• Notwithstanding paragraph (a), in the waters of the Great Lakes Basin, the manoeuvring light referred to in Rule 34 (i) shall be placed in the same fore and aft vertical plane as the masthead light or lights at not less than one metre vertically above or below the after masthead light and, where practicable, shall be placed at the minimum height of one metre vertically above the forward masthead light. On a vessel where only one masthead light is carried, the manoeuvring light, if fitted, shall be carried where it can best be seen and shall be located not less than one metre vertically apart from the masthead light.

(A1.13) High-speed craft:

• The masthead light of high-speed craft may be placed at a height related to the breadth of the craft lower than that prescribed in subparagraph 2(a)(i) of this Annex, provided that the base angle of the isosceles triangles formed by the sidelights and masthead light, when seen in end elevation, is not less than 27°.
• On high-speed craft of 50 metres or more in length, the vertical separation between foremast and mainmast light of 4.5 metres required by subparagraph 2(a)(ii) of this Annex may be modified provided that such distance shall not be less than the value determined by the following formula: y = [(a + 17ψ)C/1000] + 2
Canadian modifications exist as follows...
• The term high-speed craft means a craft that has been certified in accordance with the International Code of Safety for High Speed Craft, 2000 or the International Code of Safety for High-Speed Craft, 1994.

This rule is unlikely to appear on examinations.

(A1.14) Approval:

• The construction of lights and shapes and the installation of lights on board a vessel shall be to the satisfaction of the appropriate authority of the State whose flag the vessel is entitled to fly.
Canadian modifications exist as follows...
• For the purpose of paragraph (a), the appropriate Canadian authority is the Minister.

(A1.15) Electrical Power Supply:

Electric power, including emergency electric power, supplied to any navigation lights other than electronic lanterns shall be in compliance with the requirements of section 11.37 and the applicable provisions set out in Schedule 1 to Ship Electrical Standards, TP 127, published by Transport Canada, as amended from time to time.

(A2.1) General:

The lights mentioned herein shall, if exhibited in pursuance of rule 26d, be placed where they can best be seen. They shall be at least 0.9 meters apart but at a lower level than lights prescribed in Rule 26 b(i) and c(i). The lights shall be visible all around the horizon at a distance of at least one mile but at a lesser distance than the lights prescribed by these rules for fishing vessels.

This rule is in reference to the additional signals which may be displayed by a fishing vessel in close proximity with other fishing vessels. These lights are a pair of additional all-around lights which must displayed by fishing vessels which are greater than 20m in length, and compulsory in fishing vessels under 20m.

(A2.2) Signals for Trawlers:

• Vessels of 20 m or more in length when engaged in trawling, whether using demersal or pelagic gear, shall exhibit
  i. when shooting their nets: two white lights in a vertical line,
  ii. when hauling their nets: one white light over one red light in a vertical line,
  iii. when the net has come fast upon an obstruction: two red lights in a vertical line.
• Each vessel of 20 m or more in length engaged in pair trawling shall exhibit
  i. by night, a searchlight directed forward and in the direction of the other vessel of the pair,
  ii. when shooting or hauling their nets or when their nets have come fast upon an obstruction, the lights prescribed in paragraph 2(a) above.
• A vessel of less than 20 m in length engaged in trawling, whether using demersal or pelagic gear or engaged in pair trawling, may exhibit the lights prescribed in paragraph (a) or (b), as appropriate.

(A2.3) Signals for Purse Seiners:

Vessels engaged in fishing with purse seine gear may exhibit two yellow lights in a vertical line. These lights shall flash alternately every second and with equal light and occultation duration. These lights may be exhibited only when the vessel is hampered by its fishing gear.

the following are canadian modifications to the collision regulations...

(A2.4) Special Visual Signals:

In Canadian waters and fishing zones, a vessel engaged in pair-trawling shall exhibit at the foremast the International Code flag “T” during the daylight hours.

(A2.5) Special Sound Signals:

• In Canadian waters and fishing zones, a vessel engaged in fishing as described in sections 2 and 3 of this Annex shall, in any condition of visibility, sound the following signals on her whistle:
  i. four blasts in succession, namely, two prolonged blasts followed by two short blasts when shooting a net or gear,
  ii. three blasts in succession, namely, two prolonged blasts followed by one short blast when hauling a net or gear, and
  iii. four blasts in succession, namely, one short blast followed by two prolonged blasts, followed by one short blast when a net or gear is fast to an obstruction.
• When in or near an area of restricted visibility, the signals described in paragraph (a) shall be sounded four to six seconds after the sound signal prescribed in Rule 35(c)

(A4) Distress Signals:

1. The following signals, used or exhibited either together or separately, indicate distress and need of assistance:
• a gun or other explosive signals fired at intervals of about a minute;
• a continuous sounding with any fog-signalling apparatus;
• rockets or shells, throwing red stars fired one at a time at short intervals;
• a signal made by any signalling method consisting of the group …---… (SOS) in the Morse Code;
• a signal sent by radiotelephony consisting of the spoken word “MAYDAY”;
• the International Code Signal of distress indicated by N.C.;
• a signal consisting of a square flag having above or below it a ball or anything resembling a ball;
• flames on the vessel (as from a burning tar barrel, oil barrel, etc.);
• a rocket parachute flare or a hand-flare showing a red light;
• a smoke signal giving off orange-coloured smoke;
• slowly and repeatedly raising and lowering arms outstretched to each side;
• a distress alert by means of digital selective calling (DSC) transmitted on
  i. VHF channel 70,
  ii. MF/HF on the frequencies 2 187.5 kHz, 8 414.5 kHz, 4 207.5 kHz, 6 312 kHz, 12 577 kHz or 16 804.5 kHz; (US only)
• a ship-to-shore distress alert transmitted by the ship’s Inmarsat or other mobile satellite service provider ship earth station;
• signals transmitted by emergency position-indicating radio beacons;
• approved signals transmitted by radiocommunications systems, including survival craft radar transponders.
2. The use or exhibition of any of the foregoing signals, except for the purpose of indicating distress and need of assistance and the use of other signals which may be confused with any of the above signals, is prohibited.

3.Attention is drawn to the relevant sections of the International Code of Signals, the International Aeronautical and Maritime Search and Rescue Manual, Volume III, and the following signals:
• a piece of orange-coloured canvas with either a black square and circle or other appropriate symbol (for identification from the air); and
• a dye marker.

Canadian Modifications

4. In Canadian waters or fishing zones, in addition to the signals described in section 1, the following signals may be used or exhibited either together or separately to indicate distress and need of assistance:
• a square shape or anything resembling a square shape; and
• a high intensity white light flashing at regular intervals of 50 to 70 times per minute.
5 Notwithstanding section 2 and paragraph 4(b), a North Cardinal Buoy may use a quick flashing white light flashing at regular intervals of 60 times per minute.

6. Section 3 of this Annex shall be read as follows: “The signals in the International Code of Signals and the International Aeronautical and Maritime Search and Rescue Manual, Volume III, shall be used as the circumstances require to supplement the signals described in section 1 of this Annex. The following signals are in addition to the signals described in section 1:
• a piece of orange-coloured canvas with either a black square and circle or other appropriate symbol (for identification from the air); and
• a dye marker.”

On this list, there are 17 signals for distress, which can be considered as international signals and must be memorized, as it reflects extremely poorly on an examination applicant to fail any questions related to distress signalling. A4.1d references the widely known morse code 'SOS' for distress, though it should also be considered that seeing the more for the inverse code, OSO (---...---) could also be an indicator of distress for inexperienced or unfamiliar persons who get the prescribed morse code backwards. With flares, the presence of red stars or the color red are associated with distress, as there are other scenarios where different colored flares may be used to convey a different meaning. A4.1l mentions the transmission of a DSC alert over the radio, though it is worth noting that Canada does not have support for MF/HF radio across the country at all radio stations, because VHF is what is most widely used here. A4.2b regarding dye markers makes no reference to specific color, so the presence of any dye marker in the water is an indication of distress. With the canadian modifications to the annex, there is the addition of two more distress signals (and the mention that one signal is similar to the light characteristic of a north cardinal buoy) and the provision in A4.6 regarding rules in A4.3 which are to be taken as supplementary signals with signals from A4.1. Annex 4 is amended often, and was amended as recently as 2023 (though not majorly) and so it is prudent to refresh on this section of the rules often.

TBD

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The INTERCO: the international code of signals is an international marine publication which exists to adopt standard phrases and communications between vessels and is able to be used worldwide, irregardless of what language crewmembers speak. A current copy of this publication is available on the geospacial intelligence website. There is certain information in this publication which is intended to be memorized (flags and single flag meanings) but otherwise is intended to be kept on hand in the event that communications must be established. (wikipedia)

Flags: the most commonly used flags in the INTERCO are Hotel (I have a pilot onboard), Bravo (I am carrying/discharging/dealing in dangerous goods), and Alpha (Keep clear- I have a diver down). Due to the nature of onboard emergency, flags which are required to be flown in certain circumstances still must be flown, but it is not of immediate importance to raise flags when in an emergency onboard (an answer which may not be permissable before the transport authority but which is most practical). Flags have meanings on their own, but when combined may convey entirely different meanings (ie. Charlie is used to convey agreeance, and November conveys disagreeance; but when flown together are regarded as an international distress signal) (wikipedia)

Notices to Mariners: Notices to Mariners are published both annually and monthly by the Department of Fisheries and Oceans here. The monthly versions of the publication just contain amendments to the annual version over the course of a year, so viewing the most recent monthly version will save the effort of having to make manual corrections to the publication. The publication is split into 7 parts; A for aids to navigation, B for pilotage services, C for marine communcations and traffic services, D for search and rescue, E for marine occurances and pollution, F for national defense and military notices, and lastly part G for general information which falls under no other subheading. Due to the nature of the content, section F is of particular note as much of the information contained within it is very irregular to the ordinary practice of seamanship and so it is a positive idea to familiarize with the content even just to make oneself aware of what sort of activities are covered within this section (ie. actions to be taken after fishing up a torpedo). Being a wheelhouse publication, it is important to familiarize with Notices to Mariners in the event that something onboard is encountered that can be looked up inside the publication; like mandatory or compulsory pilotage procedures when entering Canadian waters, which are covered under section B.

Radio Aids to Marine Navigation: the radio aids to marine navigation is a wheelhouse-ready publication available here, and is published annually (and updated monthly) by the Department of Fisheries and Oceans. The publication was formerly published in two editions, pacific and atlantic, but has since been merged into one edition covering all regions of canada. There are five parts within the publication; the foreward covering miscellaneous radio communication related info (such as icebreaking services), part 2 containing information about facilities (canals/lochs and MCTS offices), part 3 covering vessel traffic services, part 4 containing general information (radio distress/service and systems info), and lastly part 5 containing information related to the environment (such as ice reporting and weather forecasting). It is advisable to become familiar with the publication in order to speed up the process of looking up specific information contained within.

Global Navigation Satellite Systems (GNSS): satellite systems considered to have global satellite coverage. There are 4 main systems active as of 2024; GPS (USA), GLONASS (Russia), BDS (China), and Galileo (Europe), and each system has a different number and configuration of satellites globally. The satellite 'waves' which transmit info to ground-based stations work via line of sight; so a clearer line of sight with a satellite will mean more accurate information. Satellite transmissions are subject to many errors, such as distortion due to the troposphere, reflection off of targets, and most importantly a difference in time (time=lag). Multiple satellites will work together to draw 'lines of position' onto a target- the accuracy of which is measured through Dilution of Position (DOP). The higher the DOP number, the less accurate the position fixing is due to greater errors affecting the signal. The GNSS System has land-based systems (GBAS), such as radio towers, which either transmit or recieve information from satellites or other ground stations in order to augment the satellite (SBAS) and air-based (ABAS) systems within GNSS.

Automatic Identification System (AIS): obtains vessel position info based off of information fed to it via GPS, rather than the vessels actual position in the world. AIS transmits different classes of information about a vessel; static and dynamic (and voyage information in class A models). The static information transmitted are things such as a vessels name, its characteristics (length and width), and what kind of ship it is. Dynamic information includes the position and speed. While only class A transponders (fitted on passenger and large ships) will transmit voyage information, that will include information like the destination headed, the number of people onboard, or the cargo. Most vessels will carry a class A transponder- the class B type are often carried by yachts and pleasurecraft. AIS is highly useful for collision avoidance (so long as the vulnerability of gps-based collision avoidance is not overlooked), search and rescue and vessel tracking. It is also integrated into the Aids to Navigaton system and there are AIS-specific navigation aids which exist digitally but not physically. You can view AIS online to see the extent of the system and how useful it is for keeping track of vessels. (wikipedia)

Magnetic Compass: During the process of construction, ships are made to have magnetic properties through external forces (magnetism flowing from one pole to the other, welding in the vicinity, etc.) as they are built primarily with ferromagnetic materials, like steel. A ship during construction will obtain permanant, temporary, and induced magnetic characteristics, all of which will contribute to magnetic deviation effecting the magnetic compass (causing it to point other directions than north). Deviation is one of many compass errors that the magnetic compass may be subject to, along with magnetic variation, which is the annual shifting of magnetic north away from 'true north' (geographic north). While the magnetic compass is typically not the primary navigational compass used in the modern age because of the errors it is subject to, it is still an effective piece of equipment as it does not require any power to function. Modern ships will normally use a gyroscopic compass or fluxgate compass for navigation, but must carry a magnetic compass as backup. Nauticalsite.in has a really fantastic article about magnetism, compasses, and compass work/course conversions used in chartwork. To minimize the effects of magnetic interference, the magnetic compass is stored in and viewed through a binnacle. In cases where the binnacle is stored outside of the wheelhouse, it can often still be read through a periscope.

Gyro Compass: a non-magnetic compass which operates under the forces of gyroscopic precession and gravity, allowing it to be made to point towards true north with a high degree of accuracy, and to continue to hold that position despite both vessel movement and rotation of the earth. A gyrocompass will take a few hours to spin up and point north but this process can be sped up via damping, which is the provision of precession to the gyrocompass to nudge it towards being north-facing. There are a lot of complicated principles that allow the gyrocompass to function, and the nauticalsite article on gyro compasswork does a great job of explaining some of it. There is an archived service manual for the 1994 sperry mark 14 gyro-compass, which explains how the compass works. The modern gyrocompass is much more compact than this model. The gyrocompass is typically hooked up to compass repeaters, which allow the heading to be read off of the repeater and feed heading information into the bridge systems.

Radar: one of the most important modern devices onboard the ship. The radar works by sending out RF energy waves, which reflect off of targets and return to the transponder; indicating the position of whatever they reflect off of. Certain materials are more reflective than others- water and steel are highly reflective; whereas wood tends to absorb the signal more. There are different types of radar antennae that serve different purposes; an 'open-array' style radar is not compatible with ships that have extensive rigging overhead- where a compact 'radome' style antennae is a far better choice. In operation of the radar it is crucial that the pulee length allows time for the signal to return- otherwise the signals will intercept one another and produce a false reading. There are two types of radar bands, X-Band ('extra-close') and S-Band. The 'X-Band' uses a lower frequency signal, and is better for collision avoidance, and close range coastal navigation. The 'S-Band' signal travels further and is better used for long range detection, for weak signals, and in the rain. It is important to scrutinize radar information and in order to detect and account for errors like 'ghost echoes', gyro misalignment and yawing. What the radar excels at is range detection- its bearing detection may not be considered accurate because multiple targets can 'merge together', but the range is subject to little error and is highly accurate. In collision avoidance radar is a crucual aide by providing distance and approximate position, in addition to giving speed information which allows the navigator to plot a relative bearing and closest point of approach using the ARPA system.

Autopilot: the autopilot system works by maintaining a set heading, as opposed to manual or hand-steering where a dedicated quartermaster is necessary to achieve this purpose. It operates either in heading (holds set heading) or track mode (follows a pre set route and alters at waypoints), and in either follow-up (rudder will automatically move to hold course) or non follow-up mode (rudder will move only under control). The autopilot is not to be considered as a replacement for the quartermaster and it must be possible to switch from auto to manual steering 'immediately', which is technically defined as 3 seconds. In close quarters and collision avoidance scenarios it is unacceptible to use to autopilot system. It is important to note that the autopilot system is considered one of the various steering systems onboard, and in the event that control is lost elsewhere it can always be tested as a back up method (as in, in addition to the emergency hydraulic controls from the steering flats). In rough weather the autopilot may not be the best choice as the yawing motion can allow it to swing between courses, causing a greater rolling motion.

Echo Sounder: an underwater device which sends out soundwaves, which are then reflected back to provide a depth reading. It works by using the difference in time between when the signal was transmitted and when it was recieved, if at all, to measure the depth travelled. As with all radar devices it is important that the pulse repetition rate and pulse repetition frequency are balanced in order for the signal to travel uninterrupted to minimize error. It is of utmost importance to always be aware of the depth of water underkeel and the echo sounder is an important device that changed depth sounding forever and phased out the lead line. If placed in an unstable position vulnerable to vessel fore-and-aft pitching, the echo sounder can also give false readings because it is moving from the position where it originally sent out its signals. The sounder should be placed perferably midships (depending on characteristics of course) and with as close to a 90 degree vertical beam projection as possible. The salinity of the water will have an effect on signal strength; meaning that in low salinity a depth reading may present as greater because the signal moves faster through the water, and in high-salinity may present as shallower beacuse the signal moves slower. The echo sounder is not a single unit; it is a system made up of different units to generate, transmit, and recieve the signals it deals with. The pulse generator generates the signals, the transducer recieves and transmits signals, the amplifier enhances the signals recieved, which is then recorded to produce a reading.

Doppler Log: a device for measuring the vessels speed by using the doppler effect. The log will transmit a signal to the seafloor, and the time difference between the transmission and retrieval is used to measure speed. A doppler log consists of multiple systems like the echo sounder. Most importantly to the navigator, the doppler log will provide a reading of speed through the water as opposed to the speed over the ground reading that GPS provides.