Outboard motor upgrade?

[Chris1956]

My neighbor's 'toon has flat aluminum welded over th bottom of the pontoons. I will guess to help it plane. He still only gets 22MPH with a 150HP Yammie.

 

[jlh3rd]

Why do people buy a poon toon ? Then expect to repower so it rides as fast as a V hull ? A round hull will NEVER come close to a V or flat bottom hull.

mainly because they/we don't understand the physics involved.
Most people think doubling HP will "double" my speed. Drag coefficients say no. A pontoon has a heavy front half. Trying to get that up with tilt just forces the back down, then more speed forces the back up, forcing the front down....repeat.....
I've tabulated my gph vs speed @RPM and basically it is a linear graph. There's a little bit of a sweet spot at 3500, but still linear.
....and don't throw wave action in the mix....

 

[dingbat]

Two things actually that they don’t understand….

In the drag calculation, the “flow speed of the object relative to the fluid” is squared, not doubled
Going from 10 to 20 mph is not (10+10 = 20) (10 x 10 = 100)

The bigger influence….Lift.
At speed, planing hulls are designed to raise out of the water, reducing the surface which drag can occur. Not so much with a pontoon boat…

At cruising speed (27 kts.), only the back 1/3 (8’) of my hull is in contact with the water, reducing drag by almost 66%, in theory

The “jump” you see in performance bulletins is the hull coming on plane.

 

[Scott Danforth]

Without a center log and lifting strakes don't bother. A pontoon is a displacement hull until you force it on top the water to be a planing hull. Until then the speed is governed by the limits of a displacement hull

Here is an 80mph pontoon. Twin 450Rs. That is 900hp

To take a pontoon from the 20mph range to the 40 mph range takes a lot of power. Beyond that, once on plane, adding more HP adds speed

 

[airshot]

Often wondered why toon mfgrs don't form the toons into a planing type hull?

 

[matt167]

Often wondered why toon mfgrs don't form the toons into a planing type hull?

Deck boats are that solution from the manufacturers

 

[jlh3rd]

yep...deck boats...
I brought that up as a question as to why they didn't really catch on...
someone's answer was pontoons are easier and cheaper to build.....cost less...

 

[airshot]

Deck boats are that solution from the manufacturers

Gotta be a big drag on a deck boat hull, I was referring to two smaller (narrower) V bottom hulls to create lift and less drag

 

[jlh3rd]

this is as close as you can get, I bet.....
I'm willing to bet I can get 3 pontoon boats for the cost of one of these.

 

[racerone]

No such thing as a ---Perfect Boat-----There is just one that is perfect for you !

 

[Chris1956]

I saw a hydrofoil for a pontoon boat. It is supposed to lift 'em a bit when cruising. They never claimed an increase in speed, but did claim fuel savings.