proping a pontoon

[cuzzx]

Have a 20ft pontoon weighing 1000lbs.

A 1995 75hp Mariner, about 300lbs.

About 100lbs of gear and gas.

Two guys at 370lbs.

Need idea as to what size prop to try on this rig.

Looking at top speed and gas comb outcome.

 

[j_martin]

Re: proping a pontoon

Have a 20ft pontoon weighing 1000lbs.

A 1995 75hp Mariner, about 300lbs.

About 100lbs of gear and gas.

Two guys at 370lbs.

Need idea as to what size prop to try on this rig.

Looking at top speed and gas comb outcome.

Don't know where to start. Prop shop or boat dealer would know. Try props till you get it to run in the max rpm range at WOT. On the high end when light, not below the low end when loaded. It's better to be a little low on pitch than high.

Then run it where it runs best for fuel, discovered by experiment. Usually around mid throttle at the point ignition timing maxes out.

hope it helps
john

 

[Silvertip]

Re: proping a pontoon

The best prop for a pontoon is a "pontoon specific" design which is affectionately called an "elephant ear" prop. These props have very large, rounded blades which gives them lots of blade area. These props also function much better in reverse than a standard prop so docking maneuvers are more controlled. You probably need a prop in the 11 - 13 pitch range. My guess is a 13P.