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Message |
    
douglas mailman
New member
Username: doug_mailman
Post Number: 1
Registered: 12-2010
| | Posted on Thursday, December 23, 2010 - 11:53 am: | 
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looking to find out what size propellar I would need for a 4hp acadia motor. |
Ernie
Senior Member
Username: ernie
Post Number: 1300
Registered: 01-2002
| | Posted on Thursday, December 23, 2010 - 12:42 pm: |
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13x13 three blade will be a good start
Hope this helps
Ernie |
John Archibald
Senior Member
Username: john_archibald
Post Number: 164
Registered: 08-2006
| | Posted on Thursday, December 23, 2010 - 01:05 pm: |
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It will be interesting to see how many suggestions this simple question draws. |
Frank Petran
Senior Member
Username: frank_petran
Post Number: 129
Registered: 05-2009
| | Posted on Thursday, December 23, 2010 - 03:59 pm: |
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A host of factors are in play here. Type of hull, length of the hull at the water line, displacement, 2 or 3 blade and use of the vessel. I had conversation with Chris Smith a while back regarding as how they use to size props. One thing that made the most sense was to size the prop so that the engine ran at its top rated torque curve verses RPM’s. It does no-one any good to have the engine destroy itself or the vessel for a few extra knots per hour or to have it bog down laboring under a heavy load. Driving a displacement vessel over the max hull speed just tends to destroy everything.
If your engine has a 13-inch flywheel, starting with a 13X13 prop is a good beginning. Become friends with the local prop shop who would let you borrow a few props for testing.
I brought home a 3 HP Acadia a while back and it came with a 2 blade prop. I know the prop is 18 inches in diameter but don't know the pitch. I'll see if I can find a chart for that prop number.
Just a side note, on my 19 foot Sea Skiff, I run a 13X12 prop and at idle, about 500 – 550 RPM’s, the boat produces a wake that I have been told by some of the local law enforcement that I am in violation of the no wake law. As the vessel is a semi-displacement hull the increase in speed requires at least a squaring of the horse power to gain one or two miles per hour until the vessel gets on plane. The vessel weights about 2200 lbs. bare hull. So one has to experiment. |
Frank Petran
Senior Member
Username: frank_petran
Post Number: 130
Registered: 05-2009
| | Posted on Tuesday, December 28, 2010 - 03:00 pm: |
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I cleaned up that propeller this morning. It is a 15 X 18 2 blade prop |
Richard A. Day Jr.
Senior Member
Username: richardday
Post Number: 930
Registered: 11-2003
| | Posted on Wednesday, December 29, 2010 - 10:54 am: |
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According to the Acadia catalog the prop sizes for the 4 HP engine are 2 Blade 15" and 3 Blade 14". I assume these were essentially square props in regard to pitch. |
