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Old 11-27-2007, 02:43 PM   #31
Chris Foster
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City: Anacortes, WA
Vessel Name: Thea
Vessel Model: 46 Grand Banks Classic
Join Date: Oct 2007
Posts: 280
Boating and fuel cost

I'm a little suspicious of the 75/75 "requirement" myself. I understand the need to avoid excessive idling and unloaded operation (like running an engine 2-3 hours to charge batteries), but haven't seen any hard evidence of long term 40-50% power shortening engine life.

Go to the John Deere marine engine web site, for example, and note that they show the identical engine with three different power outputs depending on the duty - and the engine with the lowest power rating has the longest life. For example, the 6068TFM is rated at 225 HP for "up to 800 hrs/year", but 154 HP for "over 3000 hrs/year".

Nowhere do I see any "minimum load" requirement.

Like Marin, I have an aviation side. Same discussions there - "run them at 75% or harder all the time - they love it." But those folks seemed to keep complaining about how they were always replacing cylinders once or twice between major overhauls.

Perhaps Northen Lights means "You ***can*** run them as though you hate 'em" - not "You ***must***".
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