Proper shaft size.

[TAC_Double]

I have been working on my 24' pontoon. Took it to the lake the last few weekends and have not been really happy in it's performance. I know that it's major problem is that it has a 40hp engine on it. But one thing I noticed is that the engine is an extra long shaft. The prop is under the bottom of the tubes and the cavitation plate is 23" from the top of the transom. The transom is 15" top to bottom.

Is this a correct setup or is the shaft to long?

This engine does have a 5" extent ion kit on the shaft, so I guess it could be removed.

From what I have been reading about choosing a proper shaft size is that this is too long for the transom. Would a gain anything buy altering the current setup? I am looking for a little more cruising speed.

Thanks!

 

[WillyBWright]

Re: Proper shaft size.

It sounds like an older toon with a shortshaft transom. Making the motor a shortshaft might help a little, but I can't imagine more than a 1 to 3mph improvement.

 

[TAC_Double]

Re: Proper shaft size.

Well, I have been looking at a 85hp with a 20". Would this be a better choice?

The boat is rated for a 90hp.

 

[flashback]

Re: Proper shaft size.

My sis has a 24ft toon with a 40 hp mariner.. WOT her boat might hit 17 mph. I think you would do well to get the 85hp if the boat is designed for that much.. if not you may need to beef up a few things...