(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.

(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.

(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.

(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.


Rule 13 has no exceptions; the overtaking vessel always keeps out of the way. If you are not sure whether you are overtaking another vessel, then Rule 13 says that you are.


  • Always presume the other ship does not know you are there.
  • Avoid crossing ahead – it is always safer to cross astern.
  • Do not pass close – overtaking always takes time, so make sure both ships have plenty of room to manoeuvre. Never assume that the other ship will maintain its course and speed.
  • Beware of interaction – if you are forced to pass close, be very careful of interaction between the two vessels.
  • Remain vigilant – remember; you remain an overtaking vessel until you are finally passed and clear.

Once you are an overtaking vessel, you are always an overtaking vessel. Always keep clear of a ship you are overtaking.