what size engine for dinghy

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mjb

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Oct 12, 2005
63
Beneteau 473 Huntington, NY
outboard HP for various dinghies

Thanks everybody. I've done some more research. Here are some sample HP requirements for various 10' hard sailing dinghies: Hunter Liberty - 2.5hp, Walker Bay 10 - 3hp, Dyer 9' Dhow - 2hp, Bauer 10 - 2hp, NN10-II - 2-3hp. The average hull weight is 110 lbs. I've purchased a new NN10 dinghy which has a recommended range of 2 to 3 hp. This research combined with everybody's thoughts leads me to the conclusion that I should get an outboard in the 2hp to 3.5hp range with a weight of 27 to 38 lbs. I've started a spreadsheet comparing all available outboards with less than 4 hp. Honda has a 2hp that's air cooled with a weight of 27 lbs, Suzuki and Yamaha each have a 2.5hp that weigh 30 lbs and 37 lbs respectively. Mercury, Nissan, and Tohatsu all share the same Tohatsu engine that comes in both a 2hp and 3.5hp version that shares the same engine block and weighs 38 lbs. In the case of the Tohatsu/Nissan/Mercury - why would anybody buy the 2hp version when you can buy the 3.5hp version that has nearly the identical specs except for hp rating? Also, is the displacement, bore, and stroke important or just the HP rating? Thanks for all your help. Mike
 
S

Steve Dion

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
stay away from air cooled.

Mike: I would stay away from an air cooled engine. I had one several year ago. We were running it hard and pulled the boat up on shore. I good wave doused it and froze up the engine. Stay with water cooled. Get the most HP that you boat will take. Four people and any gear will be very very slow (yes, faster than rowing, but you may not think so).
 
S

Steve Dion

.
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
stay away from air cooled.

Mike: I would stay away from an air cooled engine. I had one several year ago. We were running it hard and pulled the boat up on shore. I good wave doused it and froze up the engine. Stay with water cooled. Get the most HP that you boat will take. Four people and any gear will be very very slow (yes, faster than rowing, but you may not think so).
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Displacement , bore and stroke

are factors the determine the hp/rpm curve. You can have a small displacement high RPM engine and a large displacement lower RPM engine that develope the same hp but at different crankshaft speeds. This is why chainsaws scream and lawnmowers purr. They both develope simular hp curves but at different engine speeds.
 
Ross

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Displacement , bore and stroke

are factors the determine the hp/rpm curve. You can have a small displacement high RPM engine and a large displacement lower RPM engine that develope the same hp but at different crankshaft speeds. This is why chainsaws scream and lawnmowers purr. They both develope simular hp curves but at different engine speeds.
 
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