Thread: 12.5 mph
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  #8   IP: 108.23.219.10
Old 10-12-2011, 09:45 AM
Dave Neptune Dave Neptune is online now
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Daniel, first you ned to decide what RPM's you want to run at. As you have a light boat that is capable of far more speed that our sailboats will ever achieve under power. Also I'd like to know what vacuum you are pulling at 2000 & 2200 RPM's. My first suggestion would be to reduce the diameter and that will give you a few more RPM's and reduce the drag on the prop for a bit more power to devote to thrust. I would love to see you be able to try the Indigo, with it's narrow blades (friction reduction) and 10" diameter (additional friction reduction) and it's 7 1/4" pitch it should give you I'm guessing about 5~600 RPM's maybe even more. The Indigo should be an excelent "performance" prop on such a lite boat. I have a direct drive with the Indigo and I'm pushing 35' at 15,500 pounds and can get 2400 RPM's. If you do the math you will find that 7" is more than enough pitch to achieve your boats speeds. Maybe someone on the site near you would let you try one. If not I would look for a 2 blade 10" X 5~6" pitch and have the prop pitched up which will increase "cup" and give you a narrower focus on the thrust. DO NOT pitch a prop back as on your speedy application the prop will have considerable washout, which is a waste of power on lite boats.

The big problem is finding a prop with LESS pitch, there just not out there in anything but a sailor style. I do believe your best bet is the Indigo. Why don't you call Tom at Indigo, he is most helpful.

Dave Neptune
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