Cutlass 27 propeller

norseman54

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I have recently re-furbished a Cutlass 27 and fear that the prop is incorrect, the power unit is a Yanmar 1GM, but when throttle is applied the engine revs increase rapidly and there is a sound that woul indicate cavitation. If you have a Cutlass fitted with this engine please pass details of prop Thank you.
 

dickh

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If the prop is correct for the boat, the engine should reach almost maximum revs when fully loaded - ie flat out. Others may be able to give more specific details on the 1GM and your Cutlass.
 

norseman54

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The engine reaches full revs, but the boat only increases speed later. Full speed (5 Knots) can be gianed by gradual increase of revs but too heavy on throttle causes over revs and little increase in hull speed.
 

dickh

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Sounds very much as though the clutch is slipping in the gearbox. I know this can happen on a Hurth G/box as it happened on my previous boat and I had to rebuild it which sorted the problem. I'm assuming 1GM has a Yanmar g/box of which I know nothing about - I'm sure someone else will tell you how to sort it out. Good Luck!
 

Avocet

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Don't know anything about the Yanmar, but if it helps, Avocet has a 13" 3 bladed prop (don't know the pitch but it has 3976B stamped on it). That's driven by a 12HP engine via a Hurth HBW50 gearbox with a 2.7:1 reduction when going ahead. I can just manage 6 knots in flat water with a clean bottom. (the boat, that is!)
 
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