Action to Avoid Collision.
(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 passed 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.
Having established that there is a risk of collision, hopefully while you are still a good way from the other vessel, you will determine what action is required if you are the give-way vessel.
Course and speed changes must be such that they are obvious, both visually and on radar. Most of the well-documented collisions between commercial ships have come about because corrective action was only slight and could not be detected, until it was too late.
During daylight, a large course change would show easily to an observer observing visually from other ship, At night, the best change of heading to make, is one, which shows the watchkeeper on the other vessel, a different configuration of your own navigation lights.
What is a safe distance? Ferries crossing the busy DoverStrait aim to miss other ships by at least 1nm, although they often pass much closer to small craft. The Moving Prohibited Zone in Southampton Water bans small craft from an area 1000m (0.6nm) ahead of large ships and 100m (330ft) on either side. A ship moving at 20 knots covers 1nm every three minutes. As you can see, the further away you stay from other shipping, the better.
Paragraph (f) usually causes concern in its interpretation. Very basically it may be explained as follows:-
- Paragraph (i) says that a vessel shall take early action to avoid impeding the passage of another vessel if it is one of the vessels required so to do.
- Paragraph (ii) says that even if a risk of collision exists, if you are required not to impede the safe passage of another vessel you shall take action and at the same time ensure that whatever action you do take is in accordance with the Rules.
- Paragraph (iii) says that even if you are on a vessel whose passage should not be impeded, and another vessel gets in your way, at the end of the day, normal steering and sailing rules apply.
There is NO EXCUSE for an OOW in the open sea, ever to find himself in a close-quarters, collision-risk situation.