I have a 1979 22' Cruiser with a 1989 5.7 liter merc and a 1992 alpha 1 gen 2 outdrive with a 14X19 ss prop, the boat weight is somewhere in the 3500 lb class. I can get the boat up on plane at 4000 rpms and after up on a plane can cut back to 32/3400 rpms but engine still suonds like its reving to much would like to cut rpms back even more to around 26/2800 rpms so that i dont work the engine to hard, have had more cup added and rehubed (thought hub was slipping so had anew one replaced ) but still no difference The tech at (General Propeller) the place where i took prop said motor designed to run at 4400 rpms. But i dont want to run the engine that hard for 1 fuel econemy 2 excessive wear. My question is can i go to a bigger diameter prop and get up on plane without having to rev all the way to 4000 rpmsand still get fuel econemy. If so can someone tell me what size i can go to. I was looking at a 15 1/4 x 19 would that work