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Old 12-15-2012
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Re: overpropped vs underpropped

Quote:
Originally Posted by srah1953 View Post
I have a Yanmar 3JH5CE with SD50 saildrive. How do I know what RPM should be at WOT. The only figures I can find is that the manufacturer quotes a maximum output figure at the crankshaft which is 39hp @ 3,000 RPM. With the original fixed prop, I can get around 3,200 RPM. What does this mean in terms of being over- or under-propped?
Many thanks
In neutral, push throttle all the way forward, record rpm. Then while in gear (out and about) do the same. IMHO (same with Beneteau warranty yard) if you hit the same rpm under load as you hit in neutral you might be under-proped. Just to make your self comfortable, ask the yard who does warranty work for your model/engine.
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