Prop for 40hp Mercury 4-stroke not bigfoot

dsleep · Jun 14, 2013

I have a 2002 Fisher pontoon with a 40 hp 4-stroke EFI, would like to change props to a Solas 4 blade, what size prop would be best for this motor and boat?

jestor68 · Jun 14, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Provided the motor turns within the recommended rpm range(5500-6000) with the current prop, it is recommended to select a 4 blade of one inch less pitch in order to maintain rpm.

steelespike · Jun 14, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Welcome,what size pontoon?
Have you run it with the present prop?What size is the prop.(usually under the prop nut).
What is the wot rpm and gps speed.

dsleep · Jun 15, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

It is a 20 foot pontoon, and I am getting 5800 RPM with current prop, will pull off nut today to get current size, it's not on the blade so must be under the nut, thank you both for your quick response....

steelespike · Jun 15, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Would help to have your wot rpm and speed,preferably by gps.

dsleep · Jun 22, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

My wot rpm is now 6000, no speedo or gps, got the prop off and the only numbers found are Michigan 032141, found not under the nut but on the back side of the prop on inside washer, best I can measure it's a 12 inch prop, prop decal on motor is scratched off only number you can read is 13 which I believe is the spline number.

steelespike · Jun 22, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Your present prop is a 12 1/2 X 8" 3 blade.What is your speed some cells have a gps app.
Why did you want to try the 4 blade? I don't see a Solas 4 blade here but there is a Michigan Vortex 4 blade at a competitive price.
If your making a good strong 6000 I think you could stay with a 8" 4 blade. probably put you at about 5900.

dsleep · Jun 24, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Was hoping to get more control with the 4 blade prop, just upgraded pontoon from an 18 footer to a 20 that's heavier and less responsive in the wind with the top up, also built a boat house and would like more control trying to get it into it's slot....

steelespike · Jun 24, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

A 4 blade should give better control around the dock.How much it can respond against the wind remains to be seen.

dsleep · Jun 25, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

So are you saying to go with a 12 1/2 " x 8" x4 blade prop, in other words keep the same pitch? As opposed to the other advice to go with 1 " less pitch to get the same RPM's.

steelespike · Jun 26, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Yes I'm thinking if you have a good strong 6000 rpm you could stay with the same pitch lose 100 or so and maintain your speed better than dropping an inch of pitch.Just a hunch.

dsleep · Jun 27, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Sounds like a good plan so to be sure I'm looking for a 12 1/2 " x 8" x 4 blade prop correct ?

steelespike · Jun 27, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Don't fixate on the diameter a 4 blade may be slightly less diameter. if you have a choice of diameter get the larger one.

dsleep · Jun 28, 2013

Re: Prop for 40hp Mercury 4-stroke not bigfoot

Thanks I appreciate everyones help, thanks Mariner......

Prop for 40hp Mercury 4-stroke not bigfoot

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