Taking delivery soon and have a prop question

[Bigdaddy74]

I am running 89 octane non-ethanol fuel. I’m thinking I should exchange the 17P prop for either a 15P or 16p Saltwater Series II.

 

[Vikingstaff]

I am running 89 octane non-ethanol fuel. I’m thinking I should exchange the 17P prop for either a 15P or 16p Saltwater Series II.

If possible also run a test with only 10 gallons or slightly less of fuel, and just yourself or one more person max. That way you are at basically your lightest weight load. Get your RPM’s at WOT there.

To dial it in best, you want to be at the very top of your RPM range at WOT with the lightest load. As you add weight and people, RPM‘s will come down so that can obscure the test when carrying extra weight. I’d do one more test run on calm water, light to no wind, with as light of a load as possible. That might help you determine to determine if you want to test a 15p or 16p next, and/or adjusting motor height, etc...

 

[PartyBarge]

I was able to put a few hours on the tritoon this afternoon and after the 2 hour mark I opened it up to see how the prop would work. I ended up getting a Yamaha Saltwater Series II 15 1/2" x 17P put on to start with. My top speed is right at 44 mph at 5400 RPMs

It seemed to be be lugging a little at slow speeds just above idle. Should I try a 15 1/2" x 15P or should I try something else? I don't want to loose any speed but need about 500-600 more RPMs.

Sort of in the realm of spitting hairs, but for your stated use (moderate weight and some watersports) an SWS of lower pitch would give better acceleration and better mid-range punch. A 16p should give a little RPM headroom even if you lift the motor a bit. Running light with the 15p (especially with a motor lift) may put you a bit over 6000 RPM, if that matters to you (IF that would be the case, pulling the throttle back to hold 6000 is likely to cost a small loss of speed).

Don't expect either of those options to increase top speed much. Opening a new can of worms with an Enertia prop might get you more into your desired speed range of 45-47, but may be a lessor choice for moderate weight watersports (don't have any firm support for that although the Enertia is better known for upper end performance, not tractor duty).