I would like to get more power from my 8HP. This 27' 1976 is in great shape and the motor is just fine. To increase headway I was told to get a new three blade prop. I'm having trouble finding one to fit with the skeg design of the boat. Any thoughts?
what prop to use?
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D
Dan
3 blade is for power boats
If you are going to travel the intercoastal where it's mostly motoring, then a 3 blade prop would help. If you do more sailing then the 3 blade will kill your boat speed. Give up all hope of racing with a 3 blade.
If you are going to travel the intercoastal where it's mostly motoring, then a 3 blade prop would help. If you do more sailing then the 3 blade will kill your boat speed. Give up all hope of racing with a 3 blade.
D
Doug
Don't Over Prop
Make sure you get the right sized 3 blade. Over sized props will cause the motor to over heat and shorten life. This might not show up until you are motoring in a deep swell with head winds and or current. If it does not fit in to the space it may be to big. Then again tight space can reduce efficiency.
Make sure you get the right sized 3 blade. Over sized props will cause the motor to over heat and shorten life. This might not show up until you are motoring in a deep swell with head winds and or current. If it does not fit in to the space it may be to big. Then again tight space can reduce efficiency.
D
Dan
3 blade is for power boats
If you are going to travel the intercoastal where it's mostly motoring, then a 3 blade prop would help. If you do more sailing then the 3 blade will kill your boat speed. Give up all hope of racing with a 3 blade.
If you are going to travel the intercoastal where it's mostly motoring, then a 3 blade prop would help. If you do more sailing then the 3 blade will kill your boat speed. Give up all hope of racing with a 3 blade.
Three blade does not add more power
Acceleration will be better with 3 blades, but sustained power (cruising speed) will be the same, assuming proper matching of the prop to your engine and boat. And you will give up at least a half a knot while sailing. The improved acceleration will improve "punch" through waves, but wou will still be underpowered. I picked up a half knot with my 1977 2 blade prop (and 8 hp engine) by having the prop retuned, and a blade tip modification performed by the Alameda prop shop for under $200. But Lady Lillie is still underpowered, especially heading into a stiff wind and waves. The only way to add more _power_ is to replace the power plant - and the prop to match the new engine. David Lady Lillie
Acceleration will be better with 3 blades, but sustained power (cruising speed) will be the same, assuming proper matching of the prop to your engine and boat. And you will give up at least a half a knot while sailing. The improved acceleration will improve "punch" through waves, but wou will still be underpowered. I picked up a half knot with my 1977 2 blade prop (and 8 hp engine) by having the prop retuned, and a blade tip modification performed by the Alameda prop shop for under $200. But Lady Lillie is still underpowered, especially heading into a stiff wind and waves. The only way to add more _power_ is to replace the power plant - and the prop to match the new engine. David Lady Lillie
B
Bill Edmundson
Props.
I just did a prop calc on boat diesel.com. The original prop was 2 blade 13"x9 pitch. Max. 4.9 kts. If you go to 3 blades you need 12"x9 pitch. Same Max. 4.9 kts. We are limited by HP, not prop. You might get less prop walk with the 3 blade. The most important thing is not to overload the engine!
I just did a prop calc on boat diesel.com. The original prop was 2 blade 13"x9 pitch. Max. 4.9 kts. If you go to 3 blades you need 12"x9 pitch. Same Max. 4.9 kts. We are limited by HP, not prop. You might get less prop walk with the 3 blade. The most important thing is not to overload the engine!
3 blade will actually create more prop walk
It is not true that 3 bladed props will create less prop walk. It is true that a smaller prop (less diameter) will create less prop walk. Prop walk is reduced by having a larger clearance between the hull and the prop. David is refering to the Non-slip-tip that was patent by Killian Props. You can reach them at Bay Props in Alameda, CA.
It is not true that 3 bladed props will create less prop walk. It is true that a smaller prop (less diameter) will create less prop walk. Prop walk is reduced by having a larger clearance between the hull and the prop. David is refering to the Non-slip-tip that was patent by Killian Props. You can reach them at Bay Props in Alameda, CA.
J
John
S
Sean
just a thought
I know it's controversial so I will say this and duck. You can double your horsepower relatively cheaply by adding a kicker bracket and outboard. Also gives you 100% motor redundancy. Downside is you will mess up the lines of a very pretty boat. Also, kicker might not help you at all in a heavy sea. But I did it and I really like the setup. But I have to motor for 20 minutes against the prevailing wind every time I go out sailing. And I will say that while the outboard has failed me many times, the SB8 never has.
I know it's controversial so I will say this and duck. You can double your horsepower relatively cheaply by adding a kicker bracket and outboard. Also gives you 100% motor redundancy. Downside is you will mess up the lines of a very pretty boat. Also, kicker might not help you at all in a heavy sea. But I did it and I really like the setup. But I have to motor for 20 minutes against the prevailing wind every time I go out sailing. And I will say that while the outboard has failed me many times, the SB8 never has.
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