20’ Pontoon pitch

Stubrown12

Recruit
Joined
Jun 28, 2020
Messages
3
Recently purchased a 20’ pontoon with a 40 hp. Switched to a 75hp Mercury. The pontoon will run 18/19 mph on a 19 pitch three blade prop only turning 4000rpms. What pitch do I need and 3/4 blades. Thanks in advance.
 

WesNewell

Chief Petty Officer
Joined
Jan 3, 2018
Messages
497
A rough guess would be a 12p 4 blade. Try the mercury prop finder.
 

ahicks

Captain
Joined
Sep 16, 2013
Messages
3,957
2 stroke or 4 stroke engine?

3 blade if speed is your objective, 4 blade if max thrust is the better plan.

19p obviously way to big.
Our Honda 90 on our lightly loaded 24' toon likes a 15p 3 blade (5500/26mph), or for neck jerking hole shot (pulling), a 13p works good (6100/24mph).

A similar 75 on a lightly loaded 'toon should work good with one of those props, or maybe with an inch less pitch. Noteworthy maybe, is that the 4 strokes sound kinda busy when run at max rpm (6000). Sound MUCH better and are sometimes faster when set up at 5500.
 

ahicks

Captain
Joined
Sep 16, 2013
Messages
3,957
You may be OK with smaller kids on skis, but I would plan on lots of tubing.

I'd be tempted to try an inexpensive (Solas) 13-14p alum. 4 blade with the idea it should be close. You may end up having to buy a second prop to nail it.
 
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