We have a 9x13 prop on our tohatsu 50 hp outboard, on our 26M, it will only turn 4400 rpm. Does anyone have an idea what size prop is needed to get into the proper operating range.
prop for tohatsu 50 hp outboard
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I believe the rule of thumb is 1 inch in pitch is roughly 300-500 rpm on a gas engine. The first number on your prop size is diameter the second is pitch. 9x11 should get you to about 5500 which is about right for a 2 stroke. Check your motor specs for WOT wide open throttle rpm, it is probably less for a 4 stroke.
You really need a bigger diameter prop to get these big boats moving. Something in the range of 11.5 - 12 inches in diameter is a good start then determine your pitch from there. A pitch of 9-10" is all you can manage with a big diameter. It is the larger diameter that moves more water and provides the push to move these heavy boats not to mention the better steering and manuevering you get. Smaller diameter props only result in more slippage of the prop in the the water, which is wasted power. Measure your prop from the center to the furthest edge and then multiply by 2 to get the diameter. A small square should work.
2" of pitch is equal to 300-400 rpm, 1" is only about 150 rpm and it is not linear so to speak, it varies from boat to boat, engine to engine.
2" of pitch is equal to 300-400 rpm, 1" is only about 150 rpm and it is not linear so to speak, it varies from boat to boat, engine to engine.
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Thank you for the response. I ordered a new prop, a 12 1/10" diameter with a 9" pitch. Hope that does the trick!! Appreciate the help. We bought this gently used 2006 26M in July, we love it. We also have a 25 ' Venture with the popup top, we love it so much we felt we needed nothing but a Macgregor when we considered a newer boat. We are sailing in the gulf off the coast of Palm Harbor, FL this weekend, so we will try out the new prop. thanks again, Linda
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