Where's the best performance in rpm range?

[Forktail]

Yamaha says my F115 should run between 5000 and 6000 rpm. The motor makes maximum power at 5500. I run 35 mph at 5600 WOT with a 17 pitch prop.<br /><br />So should I be shooting for 6000 with a 15 pitch? Or jump to a 19 pitch more around 5000?<br /><br />5000-6000 seems like a WIDE range. Any suggestions guys? <br /><br />What a sweeeet outboard!

 

[Boatist]

Re: Where's the best performance in rpm range?

Forktail<br />If the readings you got is with your normal fuel and passenger weight I think you have correct prop. You want the WOT RPMS to be near the top RPMS with normal weight. On my boat a 2 inch difference in pitch makes about 400 RPM difference. You do not want to run above 6000 even with a light load. A 15 pitch might put you over 6000 with a light load. In general a prop that is a little below the top rpm range like your 17 will give highest top end speed and better fuel mileage but not get up on plane as fast. If you plan on pulling skiers or tubes the 15 might make sense otherwise I think you are ok. Do not lugg the engine with that 19 pitch.