prop questions for my 99 28zx

[subprime97]

Trying to eek out some more speed out of my 99 28zx. i currently have twin 350 mpi with the alpha drive and 3 blade 23 pitch props and seem to be about 5 mph slower than last year. any suggestions on propping or engine ...work i can have done? also, is 5000 rpm the wot on a 99 merc or am i missing something there as well. Only my second summer with this boat, first donzi so lots of questions. also contemplating a four blade prop system, any ideas? what top speed should i expect from this size boat and this engine prop combo? thanks, B

[Chili 18]

First question is why you lost 5 mph over the winter. Were rpms the same last fall? Did you paint or change the bottom? Is this the first tank of gas for this season? Couuld be old fuel perhaps? Did you switch from full synthetic engine oil to conventional? Different weight or wave conditions?? I'd say get those 5 mph back first of all.

Welcome :smile:

[subprime97]

First question is why you lost 5 mph over the winter. Were rpms the same last fall? Did you paint or change the bottom? Is this the first tank of gas for this season? Couuld be old fuel perhaps? Did you switch from full synthetic engine oil to conventional? Different weight or wave conditions?? I'd say get those 5 mph back first of all.

Welcome :smile:

did not change anything on the boat, but i am not sure what the local marina put in it when they winterized it last year. will going from a synthetic to regular oil make that much of a difference though?

b