3 to 4 blade switch

[Rob1975]

I'd like to know what prop to buy if i want to go to a 4 blade. I presently have a 13.25x17. the boat is a 16 foot tri-hull if that helps at all. Thanks

 

[steelespike]

Re: 3 to 4 blade switch

Sorry,need a lot more info.Need to know present max rpm and speed.Year brand and hp of the motor.As far as a good predictable prop goes the Solas Amita 4 blade has a good reputation.

 

[Rob1975]

Re: 3 to 4 blade switch

It has a 1974 85hp Johnson outboard, it does around 50 mph at 5000 rpm's. I say around 50 mph because the numbers are faded really bad on the speedometer.

 

[steelespike]

Re: 3 to 4 blade switch

Your present rpm is a little low yet the 17" prop is pretty typical.
your speed seems high for the rpm.A gps is better for speed.
You may want to check the motor height before a prop change.
The antivent plate(just above the prop) should be visable at speed.
usually measures about an inch above the bottom of the boat.Be sure the throttle plates are opening all the way.Is the present prop in good condition?
Why are you wanting a 4 blade prop?

 

[Rob1975]

Re: 3 to 4 blade switch

They look cool and i would like a little better/faster take off. The present prop looks like somebody tried to roto-till the bottom of the bay with it. It needs to be replaced. Another reason for wanting the 4 blade prop.

 

[steelespike]

Re: 3 to 4 blade switch

If you can't get the present prop repaired so you can get a better base line then I would suggest a 16" 4 blade.Results unknown though it will likely improve your hole shot.Stay on plane with less throttle,handle better on plane and at the dock.
You will likely lose a coup[le of mph top end.Your motor needs to operate at least at about 5,500.The 16 4 blade isn't likely to get that and I feel the solution is in your setup.

 

[Rob1975]

Re: 3 to 4 blade switch

Should i just get a 13.25x 17 3 blade to get a better baseline? I don't care about high speed, i just want it to cruise and beat my buddy on take off. Will a 4 blade not pull a tube? I am new to boating so sorry if i'm asking too many questions.

 

[steelespike]

Re: 3 to 4 blade switch

Yes a 17 will give a better indication of your setup. Along with the other suggestions I made.

 

[Rob1975]

Re: 3 to 4 blade switch

Thanks for the help, I'll try that.