Relevant documents and M-notices: MSN 1781
Rule 13 (a)
Notwithstanding anything contained in the Rules of Part B, Sections I and II, any vessel overtaking any other shall keep out of the way of the vessel being overtaken.
Part B, Sections I and II cover a lot of ground; Rules 4-18. ‘Notwithstanding’ is a very old-fashioned term with a precise legal meaning. Effectively what this part of Rule 13 means is that Rule 13 (a) applies regardless of everything else in Sections I and II.
So, if one sailing vessel is overtaking another, the one overtaking shall keep out of the way of the vessel being overtaken. This is regardless of anything that Rule 12 might say.
Rule 18 states the responsibilities between vessels ‘except where Rules 9, 10 and 13 otherwise require’. If a RAM vessel is overtaking the PDV, it is the RAM vessel which shall keep out of the way of the vessel being overtaken.
If you’re getting the idea that Rule 13 is a very powerful rule, you’re right. Imagine that you are skiing at a resort. You are a relatively new ski-er and you’re not going very fast. Someone comes flying past on your right-hand side. It’s their responsibility, as the faster skier, to keep clear of you. It wouldn’t make sense for it to be the responsibility of slower ski-ers to keep out of the way of faster ski-ers. From the International Ski Federation’s Code of Conduct on the slopes:
Other skiers ahead of you have priority. The skier who is behind (uphill) is in a position to choose their trajectory and must pick their route in such a way as to not endanger skiers or snowboarders ahead of them (downhill). The skier ahead cannot see behind, it is therefore up to the uphill skier to avoid collision.
Remember the ski-ers when you’re presented with an overtaking situation. But how to recognise an overtaking situation?
Rule 13 (b)
A vessel shall be deemed to be overtaking when coming up with another vessel from a direction more than 22.5 degrees abaft her beam, that is, in such a position with reference to the vessel she is overtaking, that at night she would be able to see only the stern light of that vessel but neither of her sidelights.
We haven’t covered navigation lights yet; that article will be linked here once live. Know for now that the sidelights of a vessel (green on starboard, red on port) show an arc from dead ahead to 22.5 degrees abaft the beam on each side. The stern light shows white from right astern to 22.5 degrees abaft the beam on each side. As for why the angle is 22.5 degrees; this is two points of the compass.
So, if you’re approaching a vessel at an angle that at night you’d be able to see her stern light, you are overtaking and shall keep out of the way of the vessel being overtaken.
But what if you’re not sure if you are overtaking?
Rule 13 (c)
When a vessel is in any doubt as to whether she is overtaking another, she shall assume that this is the case and act accordingly.
At night it is fairly easy to tell if you are overtaking. During the day however it can be less obvious. If you think you might be overtaking, act as though you are and keep out of the way of the vessel being overtaken.
Rule 13 (d)
Any subsequent alteration of the bearing between the two vessels shall not make the overtaking vessel a crossing vessel within the meaning of these Rules or relieve her of the duty of keeping clear of the overtaken vessel until she is finally past and clear.
This is often expressed as ‘once an overtaking vessel, always an overtaking vessel.’
You can’t overtake a vessel on her starboard side, then alter to port to cut across their bow in the belief that the situation is now a crossing situation.
What does this phrase finally past and clear mean? There’s no official definition, however it’s generally taken to be when no action by either vessel would cause the other vessel any concern.
How to remember that Rule 13 is Overtaking?
I remember that it’s unlucky (unlucky number 13) to be overtaken in a race.
What about in a narrow channel?
Rule 9 (e)(ii)
This Rule (Rule 9) does not relieve the overtaking vessel of her obligation under Rule 13.
So a vessel overtaking in a narrow channel must still keep out of the way of the vessel being overtaken.
What about in a TSS?
Rule 13 applies in a TSS just as in open sea.
What about in restricted visibility?
Remember that Rule 13 sits within Section II - Conduct of vessels in sight of one another. As such, it does not apply when you cannot see another vessel. So, if you see a vessel looming out of the fog and you can see her stern light, or think you might be overtaking her, keep out of the way of the vessel being overtaken.
An unusual example
In my Master Mariner Unlimited exam I was told that I’d sighted a power driven vessel on a bearing of 330 degrees. Her heading was given as 020 degrees. From the image on the slide I was clearly abaft the beam. The examiner asked me if I was overtaking, based on her bearing and heading.
Normally this would be a simple bit of maths, but in the stressful situation of an oral exam it was beyond me. I told the examiner that this was the case and, because I thought I might be in an overtaking situation, I would assume this to be the case as per Rule 13 (c). Because I ‘assume(d) that this is the case and act(ed) accordingly, I passed.
If you are presented with a situation which might be an overtaking situation (say you can sometimes see the stern light and sometimes see the sidelight), play it safe and assume you are overtaking.
MCAQs
In what conditions of visibility does Rule 13 apply?
Does Rule 13 ‘override’ Rule 18? Explain.
What does it mean to ‘keep out of the way’ of a vessel being overtaken? (See Rule 16)
What does ‘past and clear’ mean?
If you aren’t certain whether you are overtaking or crossing, what should you do?