24' pontoon w/ 1985 90hp evinrude VRO prop question.

[TDFLINT]

Can anyone out here give me an idea of what size prop I should put on this motor? I just bought the boat and it currently has a three blade badly damged prop and I need to replace it but I'm not sure what one I should buy. Any opinion on using a 4 blade or should I stick with a 3 blade?

The boat is a 1993 24' Grumman Fun Ship and weighs 2170

the prop that's on it is 3 blade with 13 teeth. Can't tell who the manufacturer of the prop is.


thanks for your help.

 

[steelespike]

Re: 24' pontoon w/ 1985 90hp evinrude VRO prop question.

There should be numbers on the barrel or under the prop nut.A 4 blade usually does well on a pontoon.If you can get the prop repaired and get some performance figures; Prop size,max rpm and speed we could tell much better what you need.
Based on your setup a 13" 4 blade would be close.The motor needs to run near the high end of its rpm rating.

 

[TDFLINT]

Re: 24' pontoon w/ 1985 90hp evinrude VRO prop question.

Okay- I took the prop off and its a Michigan 011002 which is a 13 3/4 x 15. Do you know what the four blade equivalent would be?
thanks

 

[steelespike]

Re: 24' pontoon w/ 1985 90hp evinrude VRO prop question.

A 15 seems like a little too much for your setup.Generally when going to a 4 blade
you would drop an inch.I would do a 13" in a 4 blade.If its aluminum just look up a Michigan for your motor.Keep in mind we're working blind with no specs from your setup.Your better off if you endup under propped.You can use it and just be careful
of the rpm if you end up over propped you just shouldn't use it.

 

[jasperpso2]

Re: 24' pontoon w/ 1985 90hp evinrude VRO prop question.

turning point prop calculator recommends a 17 pitch for speed, or a 15 pitch for power.. both 3 blade props.. i input your boat, motor, 3 people,and 12 gallons of gas.. so if you go down a inch pitch for a 4 blade, you would use a 16 pitch for speed, or a 14 for power..

this is just a calculater recommendation.. but my guess is not too far off.