BF15 Prop Size and Options

I got a used BF15 at the beginning of the season. It starts first pull and runs great at low to medium high speed. At full speed i am getting cavitation and difficulty keeping on plane. I was told that I may be running the wrong prop. I have a 9x8.25 four blade. Is there an option for a different prop that would give an higher top speed? I currently have a hard time keeping up on plane. I am running an industrial AB 11 ft aluminum hull inflatable. Boat is rated for up to 20 hp.

Thanks

Here's a parts page link with all thw options from Honda for these outboards.

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/15hp/bf15d4-sha-2004

(You need to select the prop shaft and propeller box to reach the page I intended...
sorry for not getting you there directly. My copy and paste skills have never "matured")

As you can see, your choices are many and more can be found from aftermarket vendors like Michigan Wheel and others.

All I can really offer as to what you might want to choose (I'm no prop guru) is that you'll probably not want to go bigger in diameter or lower in pitch in order to gain speed.

But this is all going to be very dependent on other variables like hull shape, proper outboard to transom mounting and how much load you carry and where it's placed.

If you're not turning the engine at full rpm on plane then you need to find out why. It's not always a result of the wrong prop being run.

You can, after having all your answers to THEIR questions written down and handy, ask for suggestions from one or more of the aftermarket prop manufacturers. That might help you narrow down your decision.

I wish you good fortune in your choice.

Thank you. Now I will have to weigh the acceleration vs top speed. Top speed is more important at this point. Also 3 blade vs 4 blade. Thanks again!

Yeah, the 3 blade should allow for more rpm but I didn't see one listed for that outboard.

Kind of surprising to me.

Good luck.