Need Prop sizing help

[bmoore47]

I have a 228G with ox66 225 yamaha. Hole shot is horrible and when RPM drops below 4200 boat sits down (comes off plane) speed drops dramatically. WOT is about 5700RPMS at 36-37Knots. Prop on motor is now 13.75 x 17. Any one turning something better or any good suggestions. Thanks

 

[ocnslr]

We had a single 250HP OX66 on our 270 Islander when we purchased it new. Did a lot of prop work before we repowered to the twins.

First off, I think you should be running a larger diameter prop.

The OX66 max RPM is 5500, so you are currently UNDER-propped, as shown by your 5700rpm WOT.

I would recommend you first try a Yamaha SWS 15.25" x 17". This is what we had originally on our OX66, and it should drop your WOT RPM down to about 5500.

You might also consider a PowerTech OFS4 prop, in 17" pitch. This will also drop your RPM as needed, but will give you a LOT more bite, with greatly improved hole shot and the ability to hold plane at a lower RPM. This is the prop that we had on the OX66 until we repowered. (And we have PowerTech OFS3 props on the F150s now).

You should be able to find a good prop shop in Morehead City. Let them know that you are seriously looking for a better prop and ask if you can try a few. If not, then maybe you can work with my prop guy at Bay Propeller in Chesapeake, VA.

Brian

 

[bc282]

i have to second the prop size comment that at 13" it's too small. you should be running a 15.25 - 15.5" dia prop with similar 17" pitch.
the bigger wheel will definitely help lower speeds and hole shot.

 

[Bill_N]

Look on eBay for a 17" SWS prop or better yet, a Mirage Plus 17". You should be able to find one reasonably priced there. You might need a hib kit for the Mirage Plus.

 

[otterbanx]

I'm turning a 14.75 x 17" REV 4. Motor is a F225 yamaha on an '86 228 with bottom paint & hardtop.
41+mph at 6k rpm.