You are giving way. How large must the manoeuvre be?
Large enough to be readily apparent by eye or on radar. A succession of small alterations is forbidden.
Rule 8 (b).
Part of the convention Always: clear weather and fog alike
Action must be positive, made in ample time and with due regard to good seamanship, if the circumstances of the case admit. A succession of small alterations is to be avoided precisely because nobody can see them, by eye or on radar.
- Any alteration of course or speed must be large enough to be readily apparent to the other vessel. A succession of small alterations is a classic mistake.
- If there is sea room, an alteration of course alone may be the most effective action, provided it is made in good time and is substantial.
- Action must result in passing at a safe distance, and its effectiveness must be checked until the other vessel is finally past and clear.
- You may and should slacken speed, stop or reverse if that is safer or you need time to appraise the situation.
- «Not to impede» means taking early action to leave enough room for the other vessel to pass safely, not swerving at the last moment. The duty does not lapse when risk of collision develops.
At sea it looks like this
Meeting a vessel head on, a 5-degree turn is invisible to her and you keep closing. A 25 or 30-degree turn made three miles off reads instantly by eye and on radar. That is positive action.
The rule says«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.»
Check yourself
What does the duty «not to impede» another vessel mean?
Taking early action to leave enough sea room for her safe passage. The duty does not lapse when risk of collision develops.
Rule 8 (f).