It doesn't matter whether it's a gate or a finish line, the rules regarding mark room are the same in both cases.

Rule 18 applies between boats when they are required to leave a mark on the same side and at least one of them is in the zone.

It would be the same scenario if you had a race committe that set up an excessively wide gate. In the three boat length zone(s) rule 18 apllies. In the area between the marks (but outside of the zones), the standard rules regarding when boats meet apply.

Using the committe boat or the pin end of the line to an inside boat's advantage is just part of the tactics of racing.

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