It could be One Crazy Summer with John Cusack and Demi Moore.
Hey
I've been looking for a early 90's (possibly late 80's) comedy, a bit caddyshack/revenge of the nerds-esk, where a bunch of teens have to do some kind of Yacht race for something against the jock-type rivals, and they win at the end after using their "secret weapon" which is the head jocks ferrari as the Yacht's engine...
Bit Vague and random I know,
Regards
It could be One Crazy Summer with John Cusack and Demi Moore.