Message 4 of 5
Posted by member Calum Norris on Friday 31 October 2025

Generally the greater the pitch the higher the potential top speed. I had a speedboat with a 20 inch prop that could achieve 45 knots running at 4800 rpm. By going to a lower pitch you actually gear down your engine, I nearly did with that boat for hole shot for water skiing but would have lost top speed. Therefore you would probably have been better keeping the 15pitch but reducing the diameter to allow the prop to spin up without bogging down. For example I sorted my hardy with a four blade prop of smaller pitch and diameter but achieved a higher top speed. Food for thought I guess, good luck.

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Message 2 of 5
Posted by member Calum Norris on Sunday 26 October 2025

Hi there, remember that diameter works alongside pitch as both affect the load that the motor is under. Your outboard should easily cope with a higher pitch prop but the diameter might be wrong. A good supplier would be able to advise by looking at hull type(semi displacement) and expectations. Generally the engine should always be able to reach Wide Open Throttle or WOT as specified by the manufacturer, you haven’t stated this figure but I think 5k would be close, I would expect to be travelling a lot quicker than you are at the moment as my family pilot with a 60hp can do 17knots on GPS.

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