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8

Action to Avoid Collision

One vessel before and after a substantial course alteration. Avoiding action must be positive and taken in ample time; this isolated example prescribes no universal turning direction or safe angle.

Rule 8 describes effective action to avoid collision.

a
Action must follow the Rules and, if circumstances admit, be positive, taken in ample time and consistent with good seamanship.
b
If circumstances admit, course or speed changes must be large enough to be readily apparent visually or by radar. Avoid a succession of small alterations.
c
With sufficient sea room, a substantial course change made in good time may be most effective, provided it does not create another close-quarters situation.
d
Action must result in passing at a safe distance. Check its effectiveness until the other vessel is finally past and clear, whether observing visually, by radar, or both.
e
If necessary to avoid collision or gain assessment time, slacken speed or take all way off by stopping or reversing propulsion.
f
A vessel required not to impede another must, when required, act early to allow sufficient sea room. That duty continues if collision risk develops; she must also account for the required avoiding actions. The vessel whose passage must not be impeded remains fully obliged to comply with the steering and sailing rules when risk of collision exists.
Projected options compare course alteration with combined course and speed changes near a shoal. Vessel images show possible future positions. The sketch proves no numerical passing distance and recommends no universally smaller turn.

IMO COLREG 1972Official text

Full wording of the rule, reproduced from the official source below.

(a) Any action taken 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. (b) Any alteration 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. (c) 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. (d) Action taken to avoid collision with another vessel shall be such as 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. (e) If necessary to avoid collision or 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. (f) (i) A vessel which, by any of these rules, is required not to impede the passage or safe passage of another vessel shall, when required by the circumstances of the case, take early action to allow sufficient sea room for the safe passage of the other vessel. (ii) A vessel required not to impede the passage or safe passage of another vessel is not relieved of this 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.
Source:

STCW Bridge Watch Lens

Rules 4–10 apply in any visibility.

Rules 11–18 apply to vessels in sight of one another; Rule 19 applies to vessels not in sight when navigating in or near an area of restricted visibility.

Build the traffic picture with sight, hearing, radar/ARPA and chart context.

Do not let AIS or one isolated bearing replace systematic observation.

After manoeuvring, keep monitoring bearing, range, CPA/TCPA and passing distance until the other vessel is finally past and clear.

Exam Focus

Start every scenario by classifying the encounter: overtaking, head-on, crossing, narrow channel, traffic separation, or restricted visibility.

For vessels in sight, every overtaking vessel keeps clear until finally past and clear.

Rule 13 takes precedence over Part B Sections I and II; it does not override the other Parts of COLREG.

Collision risk may exist even with an appreciable bearing change, particularly when approaching a very large vessel or a tow, or at close range.

A nearly steady compass bearing is not the only warning.

Key Takeaways

1

Take early, positive action that the other vessel can actually see or detect

2

Avoiding action should create a safe passing distance, not merely miss by chance

3

Do not be afraid to reduce speed, stop or reverse if that is the safest action

4

After manoeuvring, verify that the action is working

Common Mistakes

Making several small alterations that are hard for the other vessel to interpret

Waiting until the last moment and then blaming the other ship

Failing to monitor whether the manoeuvre has really opened the situation

Test Your Knowledge

Practise this topic and review the explanation for each answer.

More rules in this Part

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Frequently asked questions about COLREG Rule 8

What kind of action to avoid collision does COLREG Rule 8 require?

Any action shall be positive, made in ample time and with due regard to the observance of good seamanship. Alterations of course and/or speed should be large enough to be readily apparent to another vessel observing visually or by radar, and a succession of small alterations should be avoided.

Is altering course alone enough to avoid a collision?

It can be. If there is sufficient sea room, alteration of course alone may be the most effective action, provided it is substantial, made in good time and does not result in another close-quarters situation. The action must result in passing at a safe distance.

When should a vessel slow down or stop to avoid collision?

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. The effectiveness of the action must be checked until the other vessel is finally past and clear.