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Old 04-10-2014, 06:19 PM   #1
RichF
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City: Long Beach
Country: USA
Vessel Name: Tivua
Vessel Model: 36' Island Gypsy Europa
Join Date: Apr 2014
Posts: 38
Semi-displacement hull w/single 120hp Lehman. What Prop Size?

I have a 36' Island Gypsy Europa with a 120hp Lehman (2715e). It has a Warner gear box, 2:1. I have tried two different size props. Prop #1, a 24x17 four blade Michigan only allowed the boat to turn up to ~1900 RPM (8.5 knots) at wide open throttle (WOT). I switched it out that day in the yard to Prop #2, a 24x16 3 blade that I had on board as a spare. I gained another 100 RMP and about the same speed. At WOT with both props the exhaust was black, showing the engine is under heavy load. It isn't a governor issue as I tried this procedure with my hand on the actual engine throttle lever (just in case the cable had a limit nut). Does this prop seem too big? It is the only thing I can ascertain from this situation. I had two marine mechanics on board for this trial as well and the engine has a clean bill of health. ANY suggestions or advise would be great. I'm really interested in what other members have for their propellers.
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