Pontoon prop help

[zuk524]

I have a `97 16` Odyssey Ltd. twin toon w/a 40hp Nissan 2 cyl. It came with a 11.1x13 prop. Toons are 24" and in good clean condition. Carb is clean and motor runs smooth. Problem is it won`t come up to plane. The tach is inop but I feel it`s only getting maybe 4000 rpm and on GPS with myself on board it is running 2 mph! Not sure of the year of the motor but I would be willing to bet it`s original to the boat. This is my first pontoon but really, 2 mph? I had an aluminum 16` starcraft fishing boat with a 40hp Yamaha 3 cyl and it would run 27 mph and the rpm`s were definitely higher than the Nissan. I know some details are a little vague, but any ideas? Thanks in advance.

 

[MH Hawker]

Re: Pontoon prop help

A 40 on a 16 foot boat should be at least 15 plus or more. You really need to find out what the RPM is. I believe your having motor problems. I had a Nissan NS 40 c on a 20 foot boat and it would hit 17.

 

[jestor68]

Re: Pontoon prop help

Assuming that the boat starts to move when you put the motor in gear, then doesn't move much faster even though you can hear the motor revving up?

The first thing I'd check would be the prop hub for slipping.

 

[steelespike]

Re: Pontoon prop help

At 4000 rpm either the hub is slipping as suggested or the motor has issues.
You can check the hub by drawing a water proof line across the underside of the hub and prop then run the boat and check
if the line is broken. Check if the motor is on one cylinder.
Pontoons don't plane but 15-20 is possible.