Rule 13 - Overtaking
(a) Notwithstanding anything contained in the Rules 4-18, 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 a 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 sternlight 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.
I think think the biggest takeaway here is the last statement (d) where is basically says stay well clear of the vessel after you pass ie don't cut back in front to closely, and also you can not overtake a vessel on their port side then cut across their bow to port and call right of way due to a now crossing situation, nor any sort of maneuver to create a crossing situation when overtaking. That is not allowed.
And as stated if you are in doubt whether you are overtaking or not assume you are and proceed accordingly.