Honda prop question

I have a 19 ft (19-65) Carolina skiff with a 3 blade-11 3/8 dia- 12 pitch alum prop. What effect on boat & motor would happen by switching to a 11 3/4 dia prop same other specs?? In other words, a larger dia prop does what ?? Thanks, AB

What kind of motor do you have? The key to prop selection is to make sure your motor attains the recommended rpm's at WOT (wide-open throttle.) If the recommended WOT is 6000 rpm's then you want a prop that gets you between 5800 and 6200. Note that newer outboards usually have an rpm limiter built into the ECM. For example, by Honda 225 has a limiter that cuts in at 6000 rpm. The implication is that your current prop may get you to the recommended rpm's at WOT, but that may be a function of the limiter, thus a larger diameter prop may also get you to the recommended RPM.

To directly answer your question, a one inch increase in diameter will typically drop your rpm's by approximately 200 rpm, +/- 100 rpm.

There is no formula for optimizing prop performance. You need to experiment with different prop sizes (diameter and pitch) on your particular boat.

Thanks for your speedy reply- Health & happiness to you & your loved ones. I have a '05-225 hp Honda but the engine & prop in question is a 1993 - 45 hp Honda on my 19 ft Carolina Skiff. Your reply has been most useful! Regards, AB --on the Ches near USNA, Annapolis, Maryland.