For the sake of nuance, though, Eric, how do you think this applies? Suppose there is a bit of distance to go to the top of the course (1/4 mile or better) and an F18 is the leeward boat trying to fetch A-mark on a shifty course and is sailing a little high of the mark to ensure that he can make it if the wind shifts in an unfavorable direction. Meanwhile, a Melges 24, who was ahead is sailing directly at the mark is overtaken from astern and to leeward by the F18 in very close quarters (which, would be insane for the F18 because of the wind shadow...but for the sake of discussion...).
How about we say the incident is between an F18 and a Laser? Then you shouldn't have any qualms about being able to overtake, or to sail through the shadow of the windward boat. Also, the boats don't have to be in "close quarters". Rule 17 applies if the F18 establishes overlap within 36 feet (two of
her hull lengths - not two of the laser's). Also, because a Laser can roll-tack on a dime without losing much speed, she will typically sail straight towards the windward mark (ignoring the lifts). She looses less by throwing in two late tacks than by overstanding the mark. The F18 on the other hand, will very likely "take some insurance" by following the lifts above the layline. The cost for her to take two late tacks is quite high whereas she loses very little by overstanding.
So, this is an instance where the two boats have different
proper courses. Rule 17 prohibits the F18 from sailing above her
proper course (again, that is the F18's
proper course, not the Laser's) -- and she doesn't. When the F18 follows the strategy of using the lifts to "put some space in the bank", she must give the Laser room to keep clear (RRS 16.1) and the Laser must keep clear (RRS 11).
I hope that helps,
Eric
