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Old 10-04-2016, 14:45   #1
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Sailboat outboard prop - lower pitch always better?

Hi,

I have an old 2-stroke yamaha (5C) outboard from -87 on my 25' sailboat, which still runs fine. It has a 7 1/2 x 8 propeller, which is too a high pitch for a sailboat. In reverse, the traction is horrible and in forward the engine runs very heavy, with a blurry sound. This propeller looks like the shine one in the first picture.

Now, I have found a propeller with lower pitch (7 1/4 6 1/2), looks like the one in the second picture. From what I have understood, props for sailboat outboards generally have 1. lower pitch, 2. larger surface area, 3. often four blades.

The yamaha props with <7" pitch seem to all look like the second pic below. Smaller surface area. 1/4 inch smaller diameter.

Does anyone have an idea whether such a prop would actually provide more thrust?

Bonus question: found a manual online that says both type "-B" and "-BA" props will fit the 5C. Yet -B has pin drive, while -BA has splines and no pin socket. That can't work, can it?


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Old 10-04-2016, 15:30   #2
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Re: Sailboat outboard prop - lower pitch always better?

In yor placeI would contact an aftermarket prop vendor such as SOLAS. They have a wide range of designs, including four blades, which can fit your motor, and they have the expertise to advise you on the choice. We were very happy with one for a very heavy inflatable some years ago... improved performance hugely over any of the stock Suzuki props that were available.

Jim
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Old 11-04-2016, 07:22   #3
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Re: Sailboat outboard prop - lower pitch always better?

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Originally Posted by Jim Cate View Post
In yor placeI would contact an aftermarket prop vendor such as SOLAS. They have a wide range of designs, including four blades, which can fit your motor, and they have the expertise to advise you on the choice. We were very happy with one for a very heavy inflatable some years ago... improved performance hugely over any of the stock Suzuki props that were available.

Jim


I have barely been able to find any props that fit this old engine at all. But maybe a call is better than the internet when it comes to old stuff.
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