Intersting info, appreciate the posts.

a 350 is a 350. i got a 2006 mercruiser 350 mpi with a alpha 1 outdrive. cruise 3400 rpms at 28 to 30 mph depending on conditions and whether curtains ar on or off. WOT is 40 mph. very fuel efficient.

Seems right on the target.

WOT speed a useful test measure of total performance and can show issues, big and small.

As a system check for engine, hull, prop etc.

Significant differential from " avg top speed for set up ".......would likely reveal somethings not as it should be.