The question was about smaller mainsheet blocks and thinner traplines etc. Not whether a whole part of the boat was removed like a snuffer setup (or crew).

From the top om my head The guys of Miss Nylex C-class catamaran established that the whole boat incurred some 4% pure wind drag. And that includes major components like the hulls, the beams, trampoline etc. So there is your upper limit of gains.

Somewhere in that massive 4% will be the contribution of say a 10 mm thick mainsheet compared to a 8 mm mainsheet. A mainsheet that recides in very much a turbulant patch of airflow because it is in the back of the boat and by that time the flow has already encountered many components that can trip it up. That is why the rear end of a modern airplane show plain rivets without any concern for aerodynamics. Putting an more aerodynamic object in an already turbulant flow will not result in significant gains.

I wager that any of these small changes will not result in more then 0.1% drag loss and therefor in only in 2 seconds speed increase over an hour of racing. To small to be worth the trouble.

Removing a large object like the snuffer will have of course more impact but that is several orders more significant because of its size and place on the boat (in front and therefor in much less disturbed air)

Wouter