Unless you're trying to get a couple extra hundredths quicker in the quarter in some competition, not worth worrying about. Carb jetting, timing, they're all compromises anyway. But FWIW, back in the good 'ole drag racing days, we would use 1 step up in jet size and sometimes even overfloat the bowls a bit in Holleys on cold days and the air was denser. At extreme altitude changes we would even go 2-3 steps up/down in jet sizes and do the same thing. This was worth about 1/2 a tenth in the quarter in a car at best. Rarely had to mess with the timing.
In a boat, given not only the air pressure changes at altitude or temperature, and air density changes, IMHO I think it evens out. The water is also more dense the colder it is and at altitude. The jet (Or prop, DID I SAY THAT??), is gonna gain more thrust from denser water also, therein the wash.
IN a nutshell, I agree with GT, not gonna get much from tuning. Boats, from a physics standpoint, are quite a bit different than cars, where the thrust is traction. That can be fixed with burnouts and tire composition. Not so easy with boats.
To make a long story short, which is already too late, if it runs great, leave it alone.
Ray
