Pontoon Boat & Deck Boat Forum

Maybe someone can help me with my issue. I recently purchased a JC Tritoon 266 w/Honda 225. After running it out I found that WOT rpm was only hitting 4900 at 33 mph GPS. It was equipped with a Mirage Plus 15.5 x 17p. Honda recommends 5000-6000 WOT RPM. I figured I wanted to keep that as close to 6000 as possible, so my goal was somewhere >5800.

So then the adventure begins. I swapped to a vengeance 14.5 x 15p. That brought the rpm to 6200 at 35 mph GPS. Which was no good since it was bouncing off the rev limiter. Then I swapped to a vengeance 14.5 x 17p, and this is were it got weird, WOT is 5000 rpm at 33 mph. I can't explain the 1200 rpm drop by just going up 2" in pitch. I was expecting to fall right into 5800 with this prop.

I was thinking a trying a Mirage 15.75 x 15p, but these are somewhat difficult to find at a decent price just for a prop test. But I am thinking I might see the same result.

Any suggestions?
Any other user with a 266/honda 225 combo? What results are you getting from your setup?

Simple, the 15p multiplied your torque enough that the blade profile could no longer keep the engine from blowing out. Larger diameter 3 blade, 4 blade, or a more aggressive profile is needed. With 225hp on tap I vote the biggest diameter 3 blade your motor will fit. A GOOD 15 pitch should get you in the ball park of 35-37mph @ 5500 rpm with the expected 10-12% slip a tritoon, if you have strakes, should be able to achieve. It would also have enough "room" to spin up to 6000rpm @ around 40-41mph if you think it can pull that speed. Your currently seeing about 27% slip with both of those 17p props. If it doesn't have strakes than 20-25% is acceptable for slip.

No blow out is occurring unless I over trim. I was trimming up to max speed, so I am not blowing out.

Slip with the 15p vengeance was 26%. Slip with the 17p vengeance is 23%. Both are the same diameter, both have the exact same blade profile. So generally speaking I should have seen approx. 400 rpm decrease going from the 15 to the 17.

At first the change from the mirage plus 17p to the vengeance 15p I wasn't overly surprised with the 1200 rpm increase in this case since the mirage has a more aggressive cup and larger diameter. So this is why I tried the vengeance 17p as I thought it would simply just drop the RPM around 400. But the end result proved to be nearly identical to the previous mirage plus 17p. Essentially proving diameter had negligible effect either way.

So the only other variable I am thinking of that can explain this is drag, since it would remain constant. And if that is the case, going to the mirage plus 15p which even though is a larger diameter and slightly more cupped will net me the same results as the vengeance 15p.

The JC 266 does not have strakes, just a quite large center toon. But this is a very heavy toon weighing in around 4200 lbs, so at best with the 225 I would see 40 mph.

didn't really mean blowout but more slip by dropping in pitch, which you have. The old 200rpm per pitch rule comes from the go fast crowd swinging 21+ pitch props. With a drop from 17p to 15P you have a 13.3% change in pitch which is a 667rpm difference so 5000->5666 and you also gained speed which is another 6% for 2mph which bumps it to 6009rpm and the bit of extra slip got it to the 6200rpm limiter. At least with tritoons becoming popular there are more and more props on the market that are sold in 1p increments now so you could look for a 15P with more traction and be at the peak of your RPM range, or a 16P and be somewhere in the heart of your RPM range. I'd put money on a 15p mirage running a good 200-300 rpm lower than the vengence and the large blades should have a slower cruising RPM and help with docking thrust.