my understanding is, that if the boat hails for room at a mark or obstruction, regardless of entitlement you must give it to them, you can not push them the wrong side of the mark, even if it doesn't cause a collision.

Scott, At a downwind finish, when two boats on opposite gybes are shooting for the pin end of the line, the stb gybe gybe boat must give roonm for the port boat to gybe and round the mark.
(Tactical manoeuver used when the pin end is known to be favoured)

In reality, the STB guy has no better option than to shoot low under the gybing port boat and hope for the best

Scott, At a downwind finish, when two boats on opposite gybes are shooting for the pin end of the line, the stb gybe gybe boat must give roonm for the port boat to gybe and round the mark.
(Tactical manoeuver used when the pin end is known to be favoured)

18 ROUNDING AND PASSING MARKS AND OBSTRUCTIONS
In rule 18, room is room for an inside boat to round or pass between an outside boat and a mark or obstruction, including room to tack or gybe when either is a normal part of the manoeuvre.

18.1 When This Rule Applies:
Rule 18 applies when boats are about to round or pass a mark they are required to leave on the same side, or an obstruction on the same side, until they have passed it. However, it does not apply

(a) at a starting mark surrounded by navigable water or at its anchor line from the time the boats are approaching them to start until they have passed them, or

(b) while the boats are on opposite tacks, either on a beat to windward or when the proper course for one of them, but not both, to round or pass the mark or obstruction is to tack.

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