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Volvo Penta Prop Sizing

Posted: Thu Jul 24, 2025 7:51 pm
by BrettUnder
Hello,
New here (with a new new to me R6S), but learned a lot here over last few months making the purchase decision.

So, I thought this information would be easy to come by, but I can't find it...

I've got a Forward Drive, but it seems VP sizes all the duo props similarly - by numbers somewhere around 2-7. I can't find any specs, and am really not sure how this convention works. What I thought I learned is that bigger ( mostly talking diameter here) means more pull and smaller means more top end. And, I assumed VP prop sizes would be bigger (diameter) as the number goes up. Then I found a VP document that recommended prop size based on top speed, and the higher number props had higher top speed.

So, how do VP duo type props change by the size number, just diameter or diameter and pitch? Are there specs anywhere?

I guess the simplest question would be, how will my pull and top end change if I went from a K4 to K5 prop?

Thank you all!

Brett

Re: Volvo Penta Prop Sizing

Posted: Wed Aug 13, 2025 11:02 pm
by BrettUnder
Nobody knows anything about penta props?

Re: Volvo Penta Prop Sizing

Posted: Thu Aug 14, 2025 4:35 am
by AsLan7
.
So glad you found us, Brett.

VP propellers are a bit of a mystery. Usually the pitch is stamped on the hub. You may have to do some cross reference with the information in this guide to help…

https://www.kirschbaum.at/ki_prop/pdf/V ... 0Guide.pdf


And welcome aboard mate.

.

Re: Volvo Penta Prop Sizing

Posted: Tue Aug 19, 2025 8:12 pm
by stifflkd
Volvo keeps that information close to their chest. Maybe a prop shop might beable to provide some info. But if your engine is running at max RPM, then I would think you have the right setup. Going larger will most likely load the engine and smaller will over rev the engine