Rule 8: what avoiding action must look like.

What does COLREGs Rule 8 say?

Rule 8(a): any action to avoid collision must be taken in accordance with the steering and sailing rules (Part B) and, if the circumstances of the case admit, be 'positive, made in ample time' and with due regard to good seamanship.

Rule 8(b): an alteration of course and/or speed must, 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.

Rule 8(c): with sufficient sea room, an alteration of course alone may be the most effective way to avoid a close-quarters situation — if it is made in good time, is substantial, and does not lead into another close-quarters situation.

Rule 8(d): the action must result in passing at a safe distance, and its effectiveness must be checked until the other vessel is finally past and clear. Rule 8(e): if necessary, slow down or take all way off. Rule 8(f): the duties of a vessel required not to impede another.

What does 'positive, made in ample time' mean?

Positive: a clear, decisive action, not a hesitant nudge that leaves the other vessel guessing. Ample time: early enough that the action works and that the other vessel can see it working, before the situation closes down your options. Both are qualified by 'if the circumstances of the case admit' — in a crowded or confined situation you may not have every option, but the action you do take should be as positive and early as the situation allows.

The action must also fit Part B. In restricted visibility, for example, Rule 19(d) says which alterations of course to avoid, so far as possible, for a vessel detected by radar alone.

How big should an alteration of course be?

Rule 8 gives no figure in degrees. The test is in 8(b): large enough to be 'readily apparent' to someone watching by eye or by radar. By eye, that means the other vessel sees a clear change in your aspect or lights; by radar, it means the change shows up plainly on her plot. A series of small alterations does the opposite — each may be missed, and together they confuse — which is why 8(b) says to avoid them.

Is it better to alter course or slow down?

Rule 8 provides for both. Rule 8(c) says an alteration of course alone may be the most effective action when there is sufficient sea room, provided it is made in good time, is substantial, and does not result in another close-quarters situation. Rule 8(e) requires a vessel, if necessary to avoid collision or to allow more time to assess the situation, to slacken her speed or take all way off by stopping or reversing her propulsion.

8(b) applies to speed as well as course. In our view a speed reduction you rely on should be a large one: it can take longer to show on another vessel's radar plot than a bold alteration does, and combining the two is often the clearer signal.

What is a safe passing distance?

Rule 8 gives no figure. Rule 8(d) requires that the action result in passing at a safe distance, judged for the vessels, the sea room and the conditions. It also requires you to check the action 'until the other vessel is finally past and clear' — keep taking bearings and ranges after you alter, and don't resume your course until she is.

What does Rule 8(f) require?

(i) A vessel required by any of the rules not to impede the passage or safe passage of another must, when the circumstances require, take early action to allow sufficient sea room for the other's safe passage.

(ii) She is not relieved of that obligation if the two vessels approach so as to involve risk of collision, and when she acts she must have full regard to the action the steering and sailing rules may require.

(iii) The vessel whose passage is not to be impeded remains fully obliged to comply with the steering and sailing rules when the two are approaching so as to involve risk of collision.

When does the 'not to impede' duty start?

Early. 8(f)(i) asks for early action to leave sufficient sea room, so the duty applies before a risk of collision has developed, not only once it has. If risk of collision does develop, 8(f)(ii) and (iii) mean both vessels then have duties under Part B. The vessel required not to impede still must not impede, and must act with full regard to what Part B requires; the other vessel is not exempt from Part B either — which, if she is the stand-on vessel, can mean keeping her course and speed.

Which rules require a vessel not to impede another?

Among others: Rule 9(b), (c) and (d) in a narrow channel or fairway — vessels of less than 20 metres, sailing vessels, vessels engaged in fishing, and vessels crossing the channel — and Rule 10(i) and (j) in a traffic lane, for vessels engaged in fishing, vessels of less than 20 metres and sailing vessels.

How might Rule 8 come up in an MCA oral?

As the second half of a collision scenario: you have established the risk, now say what you do and how you check it. Examples of the kind of question to be ready for:

“A vessel on your starboard bow is closing on a steady bearing. Talk me through your action and how you check it.”

“When would you slow down rather than alter course?”

“What makes an alteration 'readily apparent'?”

“You've altered. When do you come back to your course?”

“What does 'not to impede' mean, and when does that duty start?”

Where do candidates go wrong on Rule 8?

The common slips: small, repeated alterations; altering without saying how the action will be checked; forgetting that slowing down or stopping is avoiding action; resuming course too soon; and treating 'not to impede' as a duty that starts only once risk of collision exists.