guy to check engine/shaft alignment - Page 2 - SailNet Community
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post #11 of 12 Old 12-07-2010
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Prop Shop - Best on East Coast

My marina uses Millers Island Propeller - They are a wholesale prop shop for the marinas and boatyards, but will do prop work for anyone who walks in, but it is pricey.

My marina gives a big discount on their listed prices for prop work - email me
and I can give you my marina's phone number.

Brian at my marina is also very good at getting the right sailboat prop combination for your boat's and engine - transmission. He works with the prop shop and they come up with the size and pitch for your boat's needs - two heads are better than one! These old guys have been around the waterfront forever - why reinvent the wheel?

Walter - Catalina 30 - Baltimore
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post #12 of 12 Old 12-08-2010
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Originally Posted by RichH View Post
Most sailboats are 'underpitched' which causes the engine to 'lug' (never developing max. rpm). Lugging causes extreme combustion chamber pressures which can lead to 'shortened' engine life ... can also cause bent piston connecting rods, hammered piston wrist-pins and hammered engine main bearings.

I state again, If the engine cant come 'close' to its spec. maximum rpm it will never develop its maximum horsepower.
Hey Rich,

I think you mean overpitched in the above statement. While I agree with you about obtaining max horsepower, I still have some problems with understanding the "lugging" problem. I have the Perkins 4-108 with a max rating of 3600 rpm. For years I've used the standard tach as a guide for seeing what I was achieving knowing that my WOT was somewhat less than the 3600. Then several years ago I put a photo tach to check out the engine tach and low and behold the thing was not calibrated and was reading high. So in effect I was running at a much lower rpm than orginally thought. Anyway I run the engine at 80 % of the WOT reading and while that limits the hp available I am still up pretty high on the torque curve. Also the temperature readings are in operational range so I'm not really sure of how this damages the cylinder walls or the connecting rods or what have you. The only thing I see that I'm sacrificing is horsepower and as long as the rpm is kept below the 80% mark and the engine is at operating temperature then everthing should be fine? Anyway it's too late considering that I've had the boat and engine since 1985.
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