Prop change,, or not

Crawfish Dundee

Petty Officer 2nd Class
Joined
Mar 16, 2017
Messages
118
I purchased a used 50HP Evinrude that came from a pontoon boat. I am mounting it onto a 16 foot aluminum fishing boat. The prop size on this engine is 12.5 X 13. Thinking that pontoons are normally turtles, should I expect a similar ride, or will I need to change the prop for a little more speed?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
47,307
Pontoons are displacement hulls. Your fishing boat is a planing hull. Youre going to need to change the prop
 

SeaDooSam

Chief Petty Officer
Joined
Feb 15, 2016
Messages
575
50 hp on an aluminum v hull? That thing should screw ic the boat is lightweight. Definitely need a different kind of prop.
 
Last edited:

Sea Rider

Supreme Mariner
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Sep 20, 2008
Messages
12,345
Tach current prop to see its wot rpm achieved as usually loaded. Compare to factory min.max wot rpm range, will know how far off that prop is. Go for a prop maximization from there for a less pitch...

Happy Boating
 

Crawfish Dundee

Petty Officer 2nd Class
Joined
Mar 16, 2017
Messages
118
50 hp on an aluminum v hull? That thing should screw ic the boat is lightweight. Definitely need a different kind of prop.


Yes, over rev I suspect.? I am thinking a 17 pitch is at the high end of the drive train specs for 50 hp. There is probably a recipe for the exact prop to match the hull someplace. Prop searches for Evinrude 50 hp 2 CY. give about 4 or 5 options of sizes, that narrows the choices.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Won't match a exact prop for that hull as "weight" has not been taken into the least consideration. Need to test prop/hull/weight to dial best prop. For that need to buy a Hardline induction hour/tach model [FONT=&quot]HR-8062-2 Follow easy installation procedure. Check Iboats, Amazon[/FONT]

Once installed, go for a wot spin as usually loaded on flat calm, no wind water cond provided that OB has a starter prop to test. If so, check max wot rpm achieved and compare them to factory min-max wort rpm range, from that reading can go maximizing other prop to suit best your boating needs.

Happy Boating
 
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