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Old 04-14-2014, 11:37 AM   #40
RichF
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City: Long Beach
Vessel Name: Tivua
Vessel Model: 36' Island Gypsy Europa
Join Date: Apr 2014
Posts: 38
Alright guys, here's the latest. Again this is with the 3 blade, Michigan, 24x16. The boat weight is ~23,000lbs. She is semi displacement and 36'. This weekend we went out to test the cruising speed and WOT speed. WOT RMP is only 1,900!! This was confirmed with a mechanical SW tach on the flywheel. The boat ran at ~8.3 knots, with some black smoke and steam from the exhaust and the engine temp spiked to 220 degrees F. Way too hot I believe for a Lehman. The sweet spot ranged from 1,600 RPM to 1,650RPM, no black smoke, 7.5 knots cruise speed and the temp dropped to 200 degrees F. The high temp worried me so I went back to the slip and changed out the impeller and wear plate. Temp didn't change but by about 5 degrees F. There are NOT mechanical gauges so I DO worry about the accuracy of the electrical meters for the water temp. I want to install some mechanical gauges for oil pres and water temp in the engine room as a good back up.

Utimately I wanted to know what you guys are running on your Lehmans and how big your boats are. My general understanding is that this prop doesn't seem too large for similar applications elsewhere and other guys get 2,400 RPM at WOT. For some reason I cannot reach the RPM and I can't understand why. Maybe it is an injector issue although the mechanic said not.

I definitely want to contact Bob at American Marine and get his opinion. After I do, I will post what he had to say for everyone info.
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