We were always told when team racing that you can take another boat to windward of the finish line as long as you also go to windward of the finish; we were also always told to start planning and executing this EARLY to make it clear to the other boat what you were doing, in case they do not know the rules (not probable in team racing, but you never know...) and so the ctb cannot get in the way, as you cannot force them into the CTB, and so you would then have to give them water to avoid the CTB, and then there may not be room for both of you to go between the CTB and an inner spacer mark, and thus you would have to let them in to cross the finish line.



As far as I know, same rules apply when fleet racing.

Edit to add; if you tack under someone, you need to get clear ahead to start luffing above close hauled.