Pontoon Boat & Deck Boat Forum

Ok, now I'm sure there are other "prop" discussions on the thread but I decided to start a fresh one.

Here's what I've got and where I'm at:

270 Manitou SHP V-Toon
250 Yam SHO

Prop - 3 blade SS
14 1/4 Diameter
18 pitch

1500-3000 RPM's - cant get out of it's own shadow
3000-4500 RPM's - mid teens - mid 20's

5500-5800 RPM's: 35-45mph depending on load and clean toons.


The dilemma - I don't like running my engine at that high RPM range (even though I know it's rated for that) for several reasons - mainly fuel consumption (20+ gph!)

Boat already comes out of the hole like a rocket so I'm not too worried about knocking the holeshot down a bit.

I need to be in the mid 30's (mph) range when I'm turning about 3000-4000 RPM.


Thinking I might go up to a 19 or a 20 pitch, changing to 4 blade and adding some diameter.

Found a place where I can get the prop(s) for less than $300 (I know wow!, even SS props), but with very limited experience re-propping I'm a bit iffy on just jumping in on this.

Any advice, experience, knowledge, or criticism is welcome.

Thanks!

I don't know but Ken at prop gods will. He is great to work with or get advice.
http://www.propgods.com/Content2/Default.aspx

We as boat owners ask so much out of our vessels. While all the time, they're just three hulled aluminum barges with displacement hulls and the aerodynamics of a block of wood. And with lifting strakes, we've fooled these hulls into getting the nosecones out of the water for improved top end speeds and better fuel efficiency.

Boats and their engines are just big compromises. Sometimes they're just incapable of doing everything we need them to do--when we need to do it.

You are in a dilemma. Yes, you could go to a higher pitch propeller that would lower rpm's at 35 mph. But you might be "lugging" your engine--asking the engine to put out more horsepower at "x" rpm's than it was engineered for. Lugging engines will not last like an engine that'll put out it's designed maximum rpm's. An overpropped boat might only pull 5000 rpm's instead of 6000 rpm's.

I don't know if your boat is properly propped for your specific needs. You may could change props or have your current prop blueprinted for somewhat improve performance. Another option would to see if SimonMotors.com could remap your ECU for more horsepower in the mid-range.

Most people think the Yamaha SHO has plenty of power down low and at middle rpm's, and they're not into 35-40 mph cruising speeds on pontoon boats. Sometimes if you want to run that fast, you've just got to be prepared to pay the price in fuel consumption.

Bryden is up to date on testing propellers and very experienced in high horsepower tritoons. Maybe he'll chime in on your situation.