Mercury Racing HP565, Manual, Page: 70 / 151

CONDITIONS AFFECTING OPERATION
58
eng
Some boat performance can be regained by dropping to a lower
pitch propeller, but engine performance will remain lower. In
some cases, a gear ratio reduction may be more beneficial. To
optimize engine performance, prop the engine to allow operation
at or near the top end of the recommended maximum RPM
range at wide open throttle with a normal boat load.