You are overtaking another vessel. Who is responsible for keeping clear?
The overtaking vessel keeps out of the way and stays bound until the other is finally past and clear.
Rule 13. It overrides the crossing rules.
Part of the convention When you can see each other
The overtaking vessel always keeps out of the way, and this rule overrides the crossing rules. Overtaking is defined by geometry: you are coming up from more than 22.5 degrees abaft her beam, that is, at night you see only her sternlight and neither sidelight.
- If in doubt whether you are overtaking, assume that you are and keep clear.
- No subsequent change of bearing between the two makes you a crossing vessel or releases you until you are finally past and clear.
At sea it looks like this
At night, fine on your starboard bow, you see one white sternlight and no sidelights. You are inside her stern sector and you are the overtaking vessel: the whole duty is yours even though she is “on your starboard side”.
The rule says“…any vessel overtaking another shall keep out of the way of the vessel being overtaken.”
Check yourself
Geometry of overtaking: from which bearing are you the overtaking vessel?
From more than 22.5 degrees abaft her beam: at night you see only her sternlight and neither sidelight.
Rule 13 (b).
You cannot tell whether this is overtaking or crossing. What do you do?
Assume it is overtaking and keep out of the way.
Rule 13 (c). Doubt is always resolved on the side of caution.
At night you see a single white light and nothing else. What do you do?
Assume you are overtaking and keep out of the way until you are sure you are not. A white with no colours is usually the sternlight of a vessel ahead: you see no sidelights, so you are in her stern sector. A vessel at anchor and a small craft with an all-round white look the same, and closing on them is still your job.
Rule 13 (c): if in doubt, assume you are overtaking. Also rules 21, 23 (d), 30.