Re-powering my seacraft

[Bushwacker]

Rene,

It sounds like you are probably in the ball park with that prop if you had more throttle left at 5000 rpm. Your optimum rpm range for that motor is 5500-5600. Step 1 in checking a prop is to make sure tach is accurate, which it will be if you're running an I-Command gage. Step 2 is to make sure mounting height is correct, so you'll need to have someone run the boat up on plane while you take a look at AV plate, the top of which should be out of the water when you're trimmed out and up on plane.

If you can connect your GPS to the I-Command system (or just buy a Lowrance GPS antenna like I did), it will display your instantaneous mpg, which really helps to dial in your optimum trim & rpm, etc. I'm running a 15x15 4B prop and my optimum cruise is also about 27 mph, around 3700 rpm at a little over 6 gph, so you're getting great mileage! With your lighter boat and more pitch, your optimum cruise will probably occur at lower rpm. Denny