Toon turbulence

[jusfloatin]

Does anyone have an idea how far forward a motor can be moved until the pontoons create enough turbulence to affect the power? Or is there?

Pontoon deck is 8' center to center of toons 6' length short

 

[EGlideRider]

Re: Toon turbulence

I'm not sure what you are asking, but there is no motor placement that will prevent or significantly affect the turbulence of pontoons plowing through the water.

 

[jusfloatin]

Re: Toon turbulence

It is a home built pontoon boat with significant hp waiting to get bolted on.
I would like to inset the power so the pontoon will still sit somewhat level when not in use.

 

[Silvertip]

Re: Toon turbulence

Generally one moves the engine backwards to AVOID the turbulence. Moving the engine forward is difficult since the engine pod is not normally movable. If you are having an issue with "bite" then the first thing to check is whether you have a short shaft motor. Pontoons almost always require a long shaft (20 inch) to get the prop down into the water. Lowering the motor (if possible) will also help reduce turbulence issues.

 

[EGlideRider]

Re: Toon turbulence

It is a home built pontoon boat with significant hp waiting to get bolted on.
I would like to inset the power so the pontoon will still sit somewhat level when not in use.

You don't want it level when not in use because then the bow may be too low when in use.

If you let us know the length and diameter of the toons and the weight and hp of this 'significant power', then you will get a more informed answer.

When I hear the word, 'significant hp' and pontoon used in the same sentence, I am thinking you want the motor as far forward as possible.

Good luck and please post pictures as the project progresses.

 

[PGFISHER]

Re: Toon turbulence

The pontoons create turbulence from only a few feet aft of their bows. Twin pontoons each generate a bow wave; and these bow waves meet and cross to create a lot of turbulent water under the deck. To get your prop out of this turbulence, you would have to move the motor to the front of the boat. I agree that lowering the motor would be better; as the water is far les turbulent only a few inches below the wakes.

 

[5150abf]

Re: Toon turbulence

I agree, the water is turbulent from the nose cones back so there isn't any "good" water under the boat.

Your size description is a little confusing to, it is 16' long and 6' wide?

To get it to set level you woudl have to have the engine almost in the center of the boat, it woud be better to leave the engine in the back and shift weight forward to balance.

 

[lncoop]

Re: Toon turbulence

I've been watching this thread but haven't contributed because I have nothing meaningful to say. However, I reeeeeeeeally want to see some pics of this thing. I know I'm not the only one. Pending visual inspection I'll be calling Franketoon.

 

[jusfloatin]

Re: Toon turbulence

I agree, the water is turbulent from the nose cones back so there isn't any "good" water under the boat.

Your size description is a little confusing to, it is 16' long and 6' wide?

To get it to set level you woudl have to have the engine almost in the center of the boat, it woud be better to leave the engine in the back and shift weight forward to balance.

I did not leave enough space between the numbers

The deck is 8' wide
Center of toon to center of toon is 6' wide
Pontoon length - short 19' 3"
Pontoon dia. 25"
Motors- I have a choice of a CW or a CCW 25" leg 150 Mercury's (government auction)

There is no motor pod as I have not designed or built it as of yet, this is a home built and designed pontoon boat.
I have got a idea for the pod but still need to figure out how to make it more adjustable for obvious reasons.


There are no plans, directions or even a suggested rating's as again this is a home built and designed project.

This project did start out with reasonable expectations and limits, it has just morphed to the point where I have to see it thru.

 

[EGlideRider]

Re: Toon turbulence

OK. If this project must be seen to completion, then you should put the motor as far forward as possible. You should also consider adding a half-toon toward the stern to help support the weight of that 150.

 

[lncoop]

Re: Toon turbulence

I think it's really cool that you undertook this project and that you have the resolve to see it through. Have you looked at the Pontoon Water Glide product advertised on here? Might be worth considering for your application. If nothing else they could probably give you some practical insight into turbulence as they've likely considered the issue a lot in their R&D phases.

 

[jusfloatin]

Re: Toon turbulence

I did design the deck so a third toon could be bolted on just incase but I decided there has to be a point where I have to say uncle.

A friend of mine came up with a load capacity of 3900lbs to submerg the toons 1/2 way. He got this number from a friend so how they were able to do it I do not know but it seems reasonable or inline with U-Fab boats.

This was how it all got started with the help of some cold pops and a couple of friends.
It was originaly to just have a 55 Johnson.

 

[EGlideRider]

Re: Toon turbulence

Ahhh, the truth comes out. Some friends and 'cold pop' will solve most any problem. And create some. LOL!!!

Assuming the math is correct, the 3900 lbs would be evenly distributed over the deck, and of course that will not be the case.

I'm an engineer, but not a mechancal engineer, so my technical background is screaming for that third toon.

Now that the problem is better defined, others will offer more qualified advise.

 

[5150abf]

Re: Toon turbulence

Now I see, what do you have to work with for the motor pod?

you aren't by chance an aluminim welder because that would make things alot easier.

That is some serious power there so you will need a pretty good pod to hold it, I am with Bennington in the weld shop so I have seen hundreds of pods over the years.

Our basic pod is rated for 150 is made of 3/16 aluminum but of coarse you would need a big break and a welder to make one, have you though of maybe cheating on this and buying one.

It would be pretty expensive but it would work and hold the engine on the boat, possibly a salvage yard would be cheaper.

This just seems like something you don't want to trial and error with as the error part could be expensive and ugly.

Motor pods are one of the few pretty genaric parts of a pontoon in that one from about any boat should fit another boat.

 

[lmuss53]

Re: Toon turbulence

I added a 10 foot long 25 inch diameter third tube to a 19 foot boat and went to 90 hp. Just about the time the boat gets to the 30 mph mark the turbulence from the center tube makes it's way back to the engine and the prop blows out. I'm either going to have move the motor down into the water or pull the center tube off in the spring.

I urge you to build a third log with the transom integrated into it. That's how I would do mine if I could do it over.

Look at high performance pontoons on youtube, you will see that about every one you see is sitting a little high in the bow, both at the dock and underway.

Good luck with the Frankentoon. POST SOME PICS!!!!

 

[jusfloatin]

Re: Toon turbulence

I thank all for your interest and suggestions which is truly welcomed.

To be realy honest I was hoping not to have to build a third toon. It is not the cost or labour but rather the stupid kid in me being urged to realy make it fast.

The hole seems to have grown.

 

[lmuss53]

Re: Toon turbulence

I regret not making my third tube into a transom tube now. I'm afraid that if you rush through this you will regret it later. I would not add just a third log to another boat I wanted to go faster in. A single third tube added for just ride and comfort is fine, but not if you are going to try to improve speed.

Look at the Tracker NV performance boats. These are 2 tube boats that really perform well. If you have to go 2 log that would be a place to look for design ideas.

I think you have to add a third tube or lifting strakes like the NV's. You have to get all that power up on top of the water, it won't get you anywhere with your tubes half submerged, trying to plow a trench through the lake.

 

[Snobike Mike]

Re: Toon turbulence

I vote we all boycott this thread until we get pics that everyone is asking for.

 

[lncoop]

Re: Toon turbulence

I vote we all boycott this thread until we get pics that everyone is asking for.

I'm in. We want pics of Frankentoon!

 

[EGlideRider]

Re: Toon turbulence

I'm in. We want pics of Frankentoon!

I agree!!!