Attached is the chart of rated continuous output. I couldn't find it but immediately but the 1 hour limit for my 3HM35F is 3400 and the instantaneous limit is 3600. When referring to 80% load I always assume the continuous limit - 3200 for me. So basically whenever I run the engine I try to maintain the tach above 2500. But RPM is only part of the equation. Usually it is good enough but with a clean prop and bottom the actual load might not be 80% since the engine has to work less hard to move the boat the through the water.
Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD
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