I have a 1973 Starcraft American 16' fiberglass boat. The motor is a 1973
Mercury 850, 85 hp.

Currently the motor has a 21 pitch prop on it. With two adults WOT results
in about 4900 rpm and 36-37 mph. The book says between 4800 and 5500 rpms at
WOT.

I'm considering going down to a 19 pitch to try to bring the rpms up a
little and hopefully give better performance when there are more than two
people onboard.

Besides being able to get out of the water faster what other performance
changes should I expect? How will it effect my top speed and fuel
comsumption?

Thanks
Mike