Part B of the COLREGs, the steering and sailing rules, is divided into three sections. Section II (Rules 11–18) applies to vessels in sight of one another and Section III (Rule 19) to restricted visibility. Section I — Rules 4 to 10 — applies in any condition of visibility, and its first four substantive rules are the ones this guide covers. They are short, they contain no exceptions, and every encounter rule assumes you are already complying with them.
Rule 5 — look-out
Rule 5 is one sentence: every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision. Three phrases carry the weight. “At all times” — including at anchor, on autopilot, and while the skipper is below. “By sight and hearing as well as by all available means” — eyes and ears first, then radar, AIS, VHF and anything else you have, appropriate to the conditions. And the purpose: a full appraisal of the situation, not just noticing a vessel.
On a yacht the practical failures are familiar: nobody looking astern before a gybe, headsail blanketing the leeward bow for an hour, the whole crew in the cockpit facing aft while someone tells a story. A proper look-out is a task assigned to a person, who scans the full horizon, including the sector hidden by the sails, at intervals short enough that a fast vessel cannot appear and arrive between scans.
Rule 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. The rule then lists the factors to take into account. For all vessels: the state of visibility; traffic density, including concentrations of fishing vessels; the manoeuvrability of the vessel, with special reference to stopping distance and turning ability; at night, the presence of background light such as shore lights or the back-scatter of your own lights; the state of wind, sea and current and the proximity of navigational hazards; and draught in relation to the available depth of water. Vessels with operational radar have an additional list about the radar's characteristics and limitations.
Safe speed is not a number and it is not the same as slow. A sailing yacht doing six knots into a harbour entrance at night against a background of shore lights, with the skipper unsure of the buoyage, may be going too fast; the same yacht doing seven knots on a clear day offshore is not. The test is whether you could take effective avoiding action and stop in a distance that fits the conditions.
Rule 7 — risk of collision
Rule 7 tells you how to decide whether the steering rules are engaged at all. Every vessel shall use all available means appropriate to the circumstances to determine if risk of collision exists; if there is any doubt, such risk shall be deemed to exist. Radar, if fitted and working, must be used properly, including long-range scanning and plotting or equivalent systematic observation of detected objects; and assumptions shall not be made on the basis of scanty information, especially scanty radar information.
Then the two considerations every candidate should be able to quote. Risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change. And 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.
Own vessel and another vessel at three successive positions with parallel bearing lines converging on a collision point.
The practical method: as soon as you see a vessel that might come close, take a compass bearing of her — hand-bearing compass, or the steering compass with her against a stanchion or shroud — note it, and take another a minute or two later. Steady bearing and closing: act. Bearing drawing ahead or aft: she will pass ahead or astern, but keep checking, because vessels alter course.
Try it: is the bearing changing?
Interactive: two converging vessels with a live compass-bearing readout demonstrating a steady bearing versus the effect of an early substantial alteration.
Rule 8 — action to avoid collision
Rule 8 describes what any avoiding action, by any vessel, must look like. Action shall, if the circumstances admit, be positive, made in ample time and with due regard to the observance of good seamanship (8(a)). Any alteration of course and/or speed shall, if the circumstances admit, be large enough to be readily apparent to another vessel observing visually or by radar; a succession of small alterations should be avoided (8(b)). If there is sufficient sea room, alteration of course alone may be the most effective action, provided it is made in good time, is substantial, and does not result in another close-quarters situation (8(c)). Action shall result in passing at a safe distance, and its effectiveness shall be carefully checked until the other vessel is finally past and clear (8(d)). And if necessary to avoid collision or to allow more time to assess the situation, a vessel shall slacken her speed or take all way off by stopping or reversing her means of propulsion (8(e)).
Two lessons for small craft. First, a five-degree alteration is invisible to a ship's bridge team and to their radar; thirty degrees is not. Second, slowing down is a legitimate and often the best action — a sailing yacht can heave to, or start the engine and stop, and it removes you from the geometry entirely.
Rule 8(f) covers the “not to impede” duties that appear in Rules 9, 10 and 18. A vessel required not to impede another shall, when the circumstances require, take early action to allow sufficient sea room for the other vessel's safe passage; she is not relieved of that duty if risk of collision later develops, and must then also have full regard to what the steering rules require; and the vessel whose passage is not to be impeded remains fully obliged to comply with the steering rules if risk of collision arises. “Not to impede” is an earlier, additional duty, not a substitute for give-way and stand-on.
The common mistake
Learners treat Rules 5–8 as background and memorise Rules 12–18 as the “real” rules. Collision investigations say the opposite: the most common causes are a look-out that was not kept, a speed that was not safe for the visibility, a risk that was not assessed because nobody took a bearing, and action that was too small and too late. If you comply with Rules 5–8, the encounter rules are usually easy; if you do not, knowing them will not help.
Check yourselfYou are motoring at night. A vessel's lights appear fine on the starboard bow. Over five minutes the bearing by hand-bearing compass goes 040°, 040°, 041°. What does Rule 7 say, and what does Rule 8 require of your action?Show answer
A bearing that does not appreciably change while the range closes means risk of collision is deemed to exist (Rule 7(d)(i)); a one-degree wander is not an appreciable change, and if you are in any doubt, risk exists. Rule 8 requires action that is positive and early, an alteration large enough to be obvious visually and on radar (not a series of small nudges), passing at a safe distance, checked until she is finally past and clear — and slowing down or stopping is allowed if you need more time. Which vessel gives way is a Rule 12–18 question, answered only after you have done this.
Key takeaways
- Rules 5–8 apply to every vessel, in every visibility, at all times.
- A proper look-out uses sight, hearing and all available means, to make a full appraisal — not just to spot vessels.
- Safe speed is judged by whether you can take effective action and stop in a distance that fits the conditions; the rule lists the factors.
- Risk of collision is deemed to exist on a steady compass bearing, and if in doubt. Take bearings.
- Avoiding action must be early, substantial, obvious, result in a safe passing distance, and be checked until past and clear. Slowing or stopping counts.
