COLREGs for the Yachtmaster

Prerequisites

This lesson assumes you already hold, or are working at, the standard of the RYA Coastal Skipper / Yachtmaster Coastal. You should be able to recognise the common navigation lights, day shapes and sound signals, and you should know the steering and sailing rules (Rules 4 to 19) well enough to apply them in daylight in open water. The RYA Yachtmaster Offshore exam has its own minimum experience: 50 days at sea, 2,500 nautical miles, at least 5 passages over 60 miles including 2 overnight and 2 as skipper, and at least half of that experience in tidal waters. You also need a GMDSS radio certificate (SRC or higher) and a valid first aid certificate before the exam.

What changes at Offshore level is not the text of the rules, but the standard expected of you. The examiner wants instinctive, correct application of the rules at night, in fog, in traffic separation schemes and in multi-vessel situations, and the judgement to know when the rules require you to depart from them.

Learning Objectives

By the end of this lesson you should be able to:

• Explain the purpose of Rule 2 (responsibility) and when it requires departure from the other rules.
• Apply the Rule 18 hierarchy of responsibilities, including vessels constrained by their draught, restricted in their ability to manoeuvre and not under command.
• Apply the conduct rules for restricted visibility (Rule 19), including the action rules of 19(d) and the meaning of safe speed.
• Navigate in and around a Traffic Separation Scheme (Rule 10), including crossing, joining, leaving and use of inshore traffic zones.
• Conduct overtaking in a narrow channel using the correct sound signals (Rules 9 and 34).
• Act correctly as a stand-on vessel when the give-way vessel fails to act (Rule 17).
• Identify vessels by lights, shapes and sound signals at night and in fog, under exam pressure.
• Recall the full set of steering and sailing rules (Rules 12 to 17), the lights of Rules 20 to 31 and the sound signals of Rules 32 to 35 at Yachtmaster Offshore standard.

RYA syllabus mapping. This lesson covers the Yachtmaster Offshore shorebased and practical exam syllabus item "IRPCS" and the course learning objectives for Advanced COLREGs Interpretation: applying the rules beyond textbook cases using good seamanship (Rules 2, 5 to 8), handling fishing fleets, TSS lanes and commercial traffic (Rules 9, 10, 18, 26), restricted visibility procedure in high-density areas (Rules 19 and 35), and identifying specialised vessel lights, shapes and signals (Rules 20 to 31, 34 and 35).

Exam note. The examiner will test COLREGs both by questions ("what is that vessel and what must I do?") and by watching how you behave when a real ship approaches. Instinctive, early, obvious action scores. Reciting rule numbers while closing a ship at 20 knots does not.

Why the Rules Exist, and Why Rigid Application Fails

The International Regulations for Preventing Collisions at Sea 1972 (COLREGs) are, in UK law, given effect by the Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations. They apply to all vessels on the high seas and connected navigable waters. They are not a set of privileges. Nowhere do the rules talk about "right of way": they talk about vessels which "shall keep out of the way" and vessels which "shall keep their course and speed". The difference matters, because the stand-on vessel has a duty, not a right.

Rule 2: Responsibility

Rule 2(a) says that nothing in the rules exonerates anyone from the consequences of neglecting to comply with the rules, or of neglecting any precaution required by the ordinary practice of seamen. Rule 2(b) says that 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.

In practice this gives you three messages:

• You cannot hide behind the letter of a rule. A stand-on vessel that holds course into a collision is also at fault.
• The rules assume vessels behave normally. When something unusual is happening (a ship that cannot see you, a fishing fleet working across a channel, a vessel acting unpredictably), you are expected to use seamanship.
• Departure is only allowed to avoid immediate danger. It is not a licence to ignore the rules because it is convenient.

Admiralty courts have repeatedly apportioned blame to both vessels in a collision. A typical judgement finds the give-way ship mostly to blame for failing to keep a proper lookout, and the stand-on vessel partly to blame for failing to take action under Rule 17 once it was obvious the other ship was not acting. The phrase used on RYA courses is "privilege is not a suicide pact".

Rules 5, 6, 7 and 8: the Foundations

Almost every collision inquiry finds a failure in one of four rules:

Rule 8 is the one most yachtsmen fail. A 10 degree alteration from a yacht at 6 knots is invisible to a ship's officer watching on radar or by eye at 3 miles. An alteration of 30 to 60 degrees, or turning to show a different sidelight, is what "readily apparent" means. Rule 8(e) also reminds you that slowing down, stopping or going astern are legitimate actions to avoid collision, and are often the best option for a yacht under engine.

The Hierarchy of Responsibilities (Rule 18)

Rule 18 lists who keeps out of the way of whom, except where Rules 9 (narrow channels), 10 (TSS) and 13 (overtaking) say otherwise. The diagram below shows the order. Each vessel keeps out of the way of all those above it.

Click to zoom

Note three points that examiners probe:

• Overtaking overrides everything. Rule 13 applies "notwithstanding anything contained in the rules of Part B, Sections I and II". A sailing yacht overtaking a trawler must keep clear of it, and a NUC vessel overtaking you would, in principle, also be the give-way vessel (although in practice you would of course help it).
• Constrained by draught is special. Rule 18(d) says any vessel other than NUC or RAM shall, if circumstances permit, avoid impeding the safe passage of a vessel constrained by her draught. "Avoid impeding" is a different duty from "keep out of the way". It means act early so that a risk of collision never develops. If a risk of collision does develop, the normal steering rules apply between the two vessels, but the CBD vessel must still navigate with particular caution.
• Sail versus power is not absolute. Under Rule 9(b) a sailing vessel or a vessel under 20 metres shall not impede a vessel that can only navigate safely within a narrow channel, and under Rule 10(j) the same applies in a TSS lane. A 12 metre yacht under sail in a buoyed channel must not get in the way of a ship that cannot leave it.

Seaplanes and WIG craft (wing in ground effect) appear at the bottom of the list; they shall in general keep well clear of all vessels.

NUC, RAM and CBD Compared

These three categories are often confused. The key difference is the reason the vessel is limited: NUC is broken, RAM is limited by the work it is doing, CBD is limited by the depth of water around it.

Click to zoom

The diagram says other vessels "shall keep clear" of all three; strictly, for CBD the duty is to avoid impeding, as explained above. Note also that a CBD vessel must navigate with particular caution having full regard to her special condition (Rule 28 and Rule 18(e)), and that Rule 18 gives CBD vessels no priority over fishing vessels or sailing vessels in the ordinary give-way sense: the protection comes from 18(d) alone.

A dredger or a vessel engaged in underwater operations which is RAM also shows two all-round reds (or two balls) on the side where the obstruction is, and two all-round greens (or two diamonds) on the side where it is safe to pass. Remember "red is dead, green is go". Small vessels engaged in diving operations that cannot show the full shape display a rigid replica of International Code flag A at least 1 metre high.

Fishing Vessels

Rule 26 distinguishes trawling (dragging a net or other gear through the water) from other fishing (nets, lines or trawls that restrict manoeuvrability but are not dragged).

Click to zoom

Both show sidelights and sternlight only when making way through the water. A fishing vessel not actually engaged in fishing (gear stowed, on passage) shows normal power-driven lights and gets no special status. Trawls are towed astern, often 1,000 m or more on a long warp, so never cross close astern of a trawler. Netters and long-liners may have gear stretching miles to one side; the white light or upward cone shows which side.

Towing

Rule 24 lights are a common exam question at night:

Click to zoom

If a tug is also RAM because the tow severely restricts her ability to deviate, she adds red, white, red. The length of tow is measured from the stern of the tug to the after end of the tow, so a yellow light over the stern light means "do not pass close astern, there is something on the end of a wire".

Restricted Visibility (Rule 19)

Rule 19 applies to vessels not in sight of one another when navigating in or near an area of restricted visibility. The crucial point is that Rules 11 to 18 do not apply. There is no stand-on or give-way vessel; every vessel has the same duty to avoid a close-quarters situation. As soon as you can see the other vessel, Rule 19 stops applying and the normal rules for vessels in sight of one another take over, even if it is still foggy.

Rule 19 requires you to:

1. Proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. A power-driven vessel shall have her engines ready for immediate manoeuvre.
2. Have due regard to the prevailing circumstances when complying with Rules 4 to 10.
3. If you detect another vessel by radar alone, determine whether a close-quarters situation is developing and/or risk of collision exists, and if so take avoiding action in ample time.
4. If that action is an alteration of course, avoid, so far as possible, an alteration to port for a vessel forward of the beam (other than one being overtaken), and an alteration towards a vessel abeam or abaft the beam.
5. Except where you have determined that risk of collision does not exist, if you hear the fog signal of another vessel apparently forward of your beam, or cannot avoid a close-quarters situation with a vessel forward of the beam, reduce speed to the minimum at which you can keep your course. If necessary take all way off, and in any event navigate with extreme caution until danger of collision is over.

The diagram below sums up the action rules of 19(d).

Click to zoom

Applying 19(d) in practice

• Target forward of the beam on either side: alter to starboard, or slow down. For a target fine on the starboard bow, a bold starboard turn takes you round its stern; for a target broad on the starboard bow a big starboard turn may run you into its path, so slowing or stopping is often better.
• Target abeam or abaft the beam on the starboard side: do not alter to starboard (towards it). Alter to port, away from it.
• Target abeam or abaft the beam on the port side: do not alter to port. Alter to starboard, away from it.
• Vessel you are overtaking, fine on the bow: an alteration to port is allowed by the exception.

Safe speed in fog

There is no fixed speed in the rules. A widely used rule of thumb is that you should be able to stop within half the visible range, so that if both vessels follow the same principle there is room for both to stop. If radar shows a target closer than you can see, go slower. A yacht with a poor radar return should assume she has not been seen and act accordingly.

Fog procedure for a yacht

1. Fix your position and plot it before the fog closes in. Note the time and log.
2. Switch on navigation lights and radar; set AIS to transmit if fitted; hoist the radar reflector (or confirm the active target enhancer is on).
3. Crew put on lifejackets; prepare the liferaft and grab bag; post a lookout forward and one aft, listening as well as looking. Engine on and ready.
4. Start the fog signal.
5. Consider leaving shipping lanes for shallow water where big ships cannot go, or anchoring.
6. Plot every radar contact (see the radar lesson). Do not act on a single observation or on AIS alone.

Sound Signals

You must know these instantly. A short blast lasts about one second; a prolonged blast four to six seconds.

Click to zoom

Vessels under 12 m need not give these signals but must make some other efficient sound signal at intervals of not more than 2 minutes.

Rule 34(a) manoeuvring signals are given only by power-driven vessels underway (a sailing yacht under engine counts), when vessels are in sight of one another and one is manoeuvring as authorised or required by the rules. The doubt signal of Rule 34(d) is different: it may be given by any vessel, power or sail, and may be supplemented by a light signal of at least five short and rapid flashes. Never use the manoeuvring signals in fog: they are for vessels in sight.

Rule 34(b) lets you add light signals to the sound signals: a flash of about one second for each short blast, with about one second between flashes, and a prolonged flash lasting four to six seconds for each prolonged blast. A yacht without a horn within reach can use a torch to signal five short flashes. Rule 36 allows any other light or sound signal to attract attention, provided it cannot be mistaken for another signal in the rules, and forbids lights that could be confused with aids to navigation.

Narrow Channels and Overtaking (Rules 9 and 13)

In a narrow channel or fairway you keep as near to the outer limit on your starboard side as is safe and practicable. Do not cross the channel if it impedes a vessel that can only navigate within it, and do not anchor in it.

Overtaking is any approach from more than 22.5 degrees abaft the other vessel's beam; at night you would see only her sternlight. If in doubt whether you are overtaking or crossing, assume you are overtaking. The overtaking vessel remains the give-way vessel until she is "finally past and clear", even if the bearing later puts her in a crossing position.

In a narrow channel, if the overtaken vessel has to take action to allow a safe passing, the overtaking vessel signals her intention and waits for agreement, as shown below.

Click to zoom

If the vessel ahead is unhappy, she sounds five short blasts. The overtaking vessel must then wait. Agreement does not transfer responsibility: the overtaking vessel still keeps clear. In practice a yacht will often call on VHF as well, but radio agreements carry risks (are you talking to the right ship?) and do not override the rules.

Traffic Separation Schemes (Rule 10)

TSSs channel shipping in congested areas such as the Dover Strait, off Ushant, Casquets, off Land's End and off the Skerries. Many are IMO-adopted and are monitored by coastguard radar (CROSS Gris-Nez and Dover Coastguard run the Channel Navigation Information Service). Breaches by yachts are reported and prosecuted.

The duties for a vessel using a TSS are:

• Proceed in the appropriate lane in the general direction of traffic flow.
• Keep clear of the separation line or zone so far as practicable.
• Normally join or leave at the termination of a lane; if joining or leaving from the side, do so at as small an angle to the general direction of traffic as practicable.
• Avoid crossing lanes, but if obliged to cross, do so on a heading as nearly as practicable at right angles to the general direction of traffic flow.
• Do not use an inshore traffic zone when you can safely use the adjacent lane, except that vessels under 20 m, sailing vessels and fishing vessels may use the ITZ, and any vessel may use it to go to or from a port or place within it, or to avoid immediate danger.
• Avoid anchoring in the scheme or near its terminations.
• Sailing vessels and vessels under 20 m shall not impede the safe passage of power-driven vessels following a traffic lane.

Crossing a TSS

The rule says heading at right angles, not track. If a tidal stream sets you along the lane, you still steer 90 degrees to the traffic flow and accept that your ground track is angled. This gives the clearest aspect to ships (they see you broadside, crossing) and the shortest time in the lane.

Click to zoom

Worked example. You must cross a TSS whose lanes run 045/225 degrees True. The lanes and separation zone together are 8 miles wide. Your boat speed under engine is 6 knots. The tidal stream sets 045 degrees at 2 knots. You steer 135 degrees True (heading at right angles). Time to cross is 8 / 6 = 1 hour 20 minutes, during which the stream carries you about 2.7 miles north-east along the lane. Your ground track will be roughly 117 degrees True. You must plan your entry point about 2.7 miles up-tide (south-west, against the stream) of where you want to leave the scheme, so that the stream carries you across the scheme to the intended exit, and check that no shallows or the scheme's termination lie in the way. If you instead tried to make good a 135 degree track you would have to head about 155 degrees, presenting a confusing aspect to ships and breaking the rule.

Before crossing, the skipper should brief the crew, have the engine running even if sailing (so that you can maintain speed and manoeuvre), pick a gap in the traffic using radar and AIS, and be prepared to slow down or turn to pass astern of ships rather than try to cross ahead. Crossing in fog is best avoided altogether.

Joining and leaving

The next diagram shows how you join at the end of a lane, or merge from the side at a shallow angle, like a car joining a motorway.

Click to zoom

Inshore Traffic Zones

Between the landward lane and the coast lies the inshore traffic zone. A yacht on coastal passage parallel to the scheme should normally use the ITZ rather than the lane.

Click to zoom

Remember that the ITZ is not empty: fishing vessels, coasters bound for local ports and other yachts use it, and the full steering rules apply.

Stand-on Vessel Action (Rule 17)

Rule 17 is graduated:

1. 17(a)(i): where one vessel is to keep out of the way, the other shall keep her course and speed.
2. 17(a)(ii): the stand-on vessel may take action as soon as it becomes apparent that the give-way vessel is not taking appropriate action.
3. 17(b): when, from any cause, the stand-on vessel 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.
4. 17(c): a power-driven stand-on vessel taking action in a crossing situation shall, if circumstances permit, not alter course to port for a vessel on her own port side.

Before acting under 17(a)(ii), you should sound at least five short and rapid blasts (Rule 34(d)), and you can supplement this with a light signal (five short flashes) and a VHF call. For a yacht, the "may act" point comes early, because a ship of 300 m doing 20 knots needs more than a mile to make a crash stop, and her turn takes several minutes to take effect. Your action should be decisive and obvious, normally a large turn to starboard to bring the ship onto your port side, or turning away to put her astern, never a turn to port across her bow.

Worked Example: Multi-vessel Night Encounter

It is 0230, visibility good, wind south-west Force 4. You are skipper of a 12 m yacht close-hauled on port tack heading 270 degrees True at 6 knots, 15 miles south of the Lizard. Ahead and to starboard you see:

• Vessel A bearing 300 degrees, showing two white masthead lights (the after one higher) and a red sidelight. It is a power-driven vessel crossing from starboard to port, more than 50 m long, heading roughly south-west to south.
• Vessel B bearing 240 degrees, showing green over white all-round lights and a red sidelight: a trawler, making way, crossing ahead of you from right to left.

You take hand-bearing compass bearings. A remains on 300 degrees after 3 minutes; range is decreasing. B's bearing is drawing left (from 240 to 233 degrees) and her range is increasing slowly.

Analysis. You are a sailing vessel; A is power-driven, so A is the give-way vessel (Rule 18) and you are the stand-on vessel with respect to A. Note that A is approaching from forward of your starboard beam; Rule 15 (crossing) applies only between two power-driven vessels, so the reason A gives way is Rule 18, not Rule 15. B is engaged in trawling, so you must keep out of B's way, and B has already crossed ahead and is drawing clear down your port side, so she is not a threat at present. Still, never pass close astern of B because of her trawl, and keep the situation under review in case she turns.

Ship A does nothing. At 2 miles the bearing is still steady. You call on VHF Ch 16 and Ch 13: "Ship on my starboard bow, approximately 15 miles south of the Lizard, this is sailing yacht Sea Swallow, I am a sailing vessel on your port bow at 2 miles, steady bearing, please advise your intentions." No answer.

The diagram below shows the decision.

Click to zoom

Action. You sound five short blasts and flash a searchlight at your sails (Rule 36 permits signals to attract attention that cannot be mistaken for any other signal). Rule 17(a)(ii) now allows you to act and, because you are a slow vessel and the ship is fast, you should act now rather than wait for 17(b). A turn to port would take you across her bow and, in this case, also towards the trawler's gear. A bold turn to starboard, bearing away onto a heading of about 340 degrees and then gybing or tacking round as needed, puts the ship on your port side and passes astern of her. The trawler is on your port side, so a starboard turn also takes you away from her gear. You keep turning until A's bearing is drawing clearly right and her red sidelight is drawing aft, then hold until she is past and clear.

Afterwards. Record the times, bearings, VHF calls and action in the log. A near-miss can be reported to the MAIB.

The Steering and Sailing Rules in Full (Rules 11 to 18)

The advanced rules above sit on top of the basic conduct rules, which the examiner expects you to recite and apply without hesitation. They apply to vessels in sight of one another.

Two points trap candidates. First, Rule 14 head-on applies only between power-driven vessels (two sailing yachts meeting head-on are governed by Rule 12, and a yacht under power meeting a yacht under sail is governed by Rule 18). A power-driven vessel sees the masthead lights in line or nearly in line, and both sidelights, ahead. Second, a sailing vessel with her engine running and in use, even with sails up, is a power-driven vessel for the purposes of the rules. By day she should show the motor-sailing cone, point down, in the forepart of the vessel where it can best be seen (Rule 25(e)); the cone is the signal that you will be treated as power-driven, so use it.

Lights, Shapes and Sound: the Quick Reference

Because the examiner can ask about any vessel at any time, this section collects the other lights of Parts C and D that a yacht skipper must know. Rule 22 sets the minimum ranges: for a vessel of 50 m or more, the masthead light 6 miles, sidelights 3 miles, sternlight 3 miles; for a vessel of 12 m to under 50 m, the masthead light 5 miles (3 miles if under 20 m), sidelights 2 miles, sternlight 2 miles; for a vessel under 12 m, masthead 2 miles, sidelights 1 mile, sternlight 2 miles. Visible range matters: your yacht's lights are seen at only 2 or 3 miles, which is why a ship closing at 20 knots may only see you about 6 to 9 minutes before reaching you.

A sailing vessel under 20 m may not show the tricolour and the red-over-green lights together, and the tricolour is for sail only: when you start the engine you must show the masthead steaming light and the normal sidelights, because the tricolour is not a power-driven vessel signal. Many yachtsmen sail with the tricolour and a masthead steaming light on at the same time, which is illegal because it shows a power-driven vessel and a sailing vessel at once.

Rule 3(l) defines "restricted visibility" as any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms or any other similar causes. It is decided by what you can see, not by the weather forecast or by whether the sun has set. Rule 3(k) defines vessels as being in sight of one another only when one can be observed visually from the other: a ship you can see only on radar, or only by her lights glimpsed through fog, is not in sight, and Rule 19 governs.

Night Identification Drill

At Offshore level you will be asked to identify lights in rapid succession. Work through them systematically:

1. Colours and arrangement of all-round lights first (they give the vessel's status: NUC, RAM, CBD, fishing, pilot, anchored, aground).
2. Masthead lights (power-driven, length over 50 m if two, towing if stacked).
3. Sidelights (which way she is heading relative to you: red means you are on her port side).
4. What you must do (keep clear, avoid impeding, stand on).

Common Mistakes

• Holding on as stand-on vessel until it is too late. A yacht has limited speed; act under Rule 17(a)(ii) early and obviously.
• Making small, repeated alterations. Rule 8 requires a single bold alteration that is apparent on radar and by eye.
• Applying the steering rules in fog. Under Rule 19 there is no stand-on vessel. If you are thinking "I am a sailing vessel, he must keep clear of me" in fog, you are wrong.
• Turning to port for a radar target forward of the beam. Prohibited by 19(d)(i) except when overtaking.
• Crossing a TSS at an angle to save distance. The heading must be at right angles to the flow, regardless of tidal set.
• Using the TSS lane when the ITZ is available, or cutting across the separation zone. Both are reportable offences.
• Treating sailing as top of the hierarchy. Sailing vessels give way to NUC, RAM, fishing vessels and avoid impeding CBD vessels, and in channels and TSS lanes must not impede large ships.
• Relying on AIS or VHF agreements. AIS data can be wrong or missing; VHF calls may reach the wrong ship. Use bearings, radar plotting and the rules.
• Passing close astern of trawlers or between a tug and its tow.

How Collisions Are Judged

Although UK and international courts reach different conclusions on facts, the pattern is consistent and is the reason the examiner pushes you on seamanship. Blame is commonly shared between the vessels. The give-way vessel is faulted for failing to keep out of the way (Rules 8 and 16) and for a poor lookout (Rule 5). The stand-on vessel is faulted for failing to act when it was clear the other was not acting (Rule 17), for excessive speed in poor visibility (Rule 6), for a poor lookout, or for an alteration that made matters worse. In a TSS, a small vessel crossing at the wrong angle or hindering a ship in a lane is likely to be found at fault. Keep records: the log, bearings, times, VHF calls and any radar or AIS screenshots are your evidence.

Summary

• Rule 2 overrides everything: avoid collision, using seamanship, and do not shelter behind a "right of way".
• Rules 5 to 8 (lookout, safe speed, risk of collision, action) underpin every encounter. Act early, boldly and verify.
• Rule 18 sets the hierarchy: power gives way to sailing, fishing, NUC and RAM; sailing gives way to fishing, NUC and RAM; fishing gives way to NUC and RAM; everyone except NUC and RAM avoids impeding a vessel constrained by her draught. Overtaking vessels always keep clear.
• In restricted visibility, Rule 19 applies to vessels not in sight of each other: no stand-on vessel, safe speed, and no turns to port for targets forward of the beam or towards targets abeam or abaft.
• In a TSS, follow the lane in the direction of flow, join and leave at the ends or at a shallow angle, cross with your heading at right angles, and use the ITZ when on coastal passage.
• The stand-on vessel may act once the give-way vessel is clearly not acting, and must act when collision cannot be avoided by the give-way vessel alone.
• Know every light, shape and sound signal instantly.

Check Your Understanding

1. In fog you detect by radar a vessel bearing 060 degrees relative, range 4 miles, closing on a steady bearing. Which way may you not alter, and what are your best options?

Answer: The target is forward of the beam on the starboard side, so under Rule 19(d)(i) you must avoid altering to port. A bold alteration to starboard to pass astern of it is possible but may close the target if it is broad on the bow, so reducing speed or stopping (taking all way off) is often the better option. Plot to confirm the action is working.

1. You are a 12 m sailing yacht in the Dover Strait TSS, heading along the north-east bound lane. A tanker overtaking you from astern is on a steady bearing. Who must keep clear?

Answer: The tanker is overtaking, so under Rule 13 she must keep out of the way. However, Rule 10(j) means you should not impede her safe passage while she follows the lane, and as a small yacht you should not have been using the lane if the ITZ was available. In practice you should act early to avoid creating a close-quarters situation.

1. What lights does a vessel constrained by her draught show, and what is the duty of other vessels?

Answer: Three all-round red lights in a vertical line in addition to normal power-driven lights; a cylinder by day. Other vessels (except NUC and RAM) must, if circumstances permit, avoid impeding her safe passage.

1. You need to cross a TSS lane running 090/270 degrees with a north-going tidal stream of 2 knots. What heading do you steer?

Answer: 000 or 180 degrees True (whichever direction you are crossing), i.e. a heading at right angles to the traffic flow. You accept that your ground track will be angled by the stream.

1. At night you see a red over white all-round light with a second white light lower down and well to one side. What is it?

Answer: A vessel engaged in fishing other than trawling, with outlying gear extending more than 150 m horizontally in the direction of the second white light. Keep clear and pass on the other side.

1. You are stand-on and a ship is closing on a steady bearing without altering. List your actions in order.

Answer: Sound at least five short and rapid blasts (and/or five short flashes); try a VHF call identifying the ship by position; once it is apparent she is not acting, take early, bold action under Rule 17(a)(ii), normally a large turn to starboard or turning away, never to port across her bow; continue to monitor until past and clear; log the event.

1. What does two prolonged followed by two short blasts mean, and what is the correct reply if agreed?

Answer: In a narrow channel, "I intend to overtake you on your port side". Agreement is prolonged, short, prolonged, short. If not agreed, the vessel ahead sounds five or more short blasts.

1. What are the fog signals for a sailing vessel and for a vessel at anchor under 100 m, and at what intervals?

Answer: Sailing vessel: one prolonged and two short at intervals of not more than 2 minutes. At anchor under 100 m: rapid ringing of the bell for about 5 seconds at intervals of not more than 1 minute, optionally with one short, one prolonged, one short to warn an approaching vessel.

1. Why does Rule 19 not use stand-on and give-way vessels?

Answer: Because vessels not in sight of one another cannot reliably determine each other's aspect, type or status. Every vessel must therefore take its own action to avoid a close-quarters situation, using radar and listening, with rules that bias action to starboard and slowing down.

1. A trawler showing green over white and a red sidelight is crossing ahead of you from starboard to port, bearing drawing left. Is it safe to pass close astern?

Answer: No. A trawler tows its net astern, often on a long warp. Give her a wide berth, pass well astern or, better, alter to keep well away until the gear is clear.

1. Two sailing yachts approach each other. Yacht A has the wind on her port side; yacht B has the wind on her starboard side. Who gives way, and which rule applies?

Answer: Yacht A (wind on the port side) keeps out of the way of yacht B under Rule 12(a)(i). If A cannot tell which side B has the wind on and B is to windward, A still keeps out of the way (Rule 12(a)(iii)).

1. You are motor-sailing in daylight with the mainsail up and the engine running. What are you in the rules, and what must you show?

Answer: A power-driven vessel (Rule 3(b) and Rule 25(e)). By day you should show a cone, apex down, forward where it can best be seen. At night you show the lights of a power-driven vessel, including a masthead steaming light, and not just the sailing lights. Other vessels will treat you as power-driven: you give way to sailing vessels and the rest of the Rule 18 list.