Yamaha jet drive on a toon?

[maharg]

Has anyone heard of running a jet drive outboard to a pontoon? I was looking at motors and these caught my eye ( I have young ones ).

 

[EricJRW]

Re: Yamaha jet drive on a toon?

I asked the same thing a while back (while in a boat store) and what I was told (basically) is that HP for HP, you'll get more out of a prop. If top speed and performance (for the boat's rated engine size) are not top priorities, then maybe it's OK (but I really don't know, especially in regards to the intake and it sitting between the pontoons, not behind a single hull).

Looking forward to hearing more replies on this subject.

 

[lncoop]

Re: Yamaha jet drive on a toon?

I forget what the ratio is, but a jet motor has less hp than an othewise identical propped motor. The other thing to consider is the significant amount of turbulence that occurs behind a pontoon motor pod. I suspect that would be an impediment to good performance from a jet. That's just speculation though. I'm sure someone at a pontoon manufacturer could give you a more definitive answer.

 

[Silvertip]

Re: Yamaha jet drive on a toon?

Some years ago one of the pontoon makers installed a jet drive inside each of the pontoons. That was the last time I saw that configuration so that would seem to indicate jet drives are not meant for pontoons. That said, there are ocean going vessels that are jet powered and they go like crazy -- the down side is the fuel consumption is very high and I suspect the engines take a beating from having to run so fast. Jet driven catamaran ferries are used in some port cities like Sydney, Australia. Very cool indeed.

 

[river critter]

Re: Yamaha jet drive on a toon?

The loss of HP is about 1/3 ex. a 60/40 johnson 60 at top 40 at the jet. They like the fuel kiinda like a jet ski if it aint wide open your not moving. Around here some rivers have HP limits. People would by a new motor and new decals that were under the limit. HAve you ever seen a 25hp jet out run a 50 hp prop...I have.

 

[Mi duckdown]

Re: Yamaha jet drive on a toon?

That would be the biggest waste of money. Jets are for skinny water.
Pontoons don't run skinny.

 

[Silver Eagle]

Re: Yamaha jet drive on a toon?

If you could mount it in the middle of the pontoon boat ,and have direct steering it may work.It would turn on a dime. I know a guy who put an out board motor in the center of his 28 ft Pontoon boat. It was a 150 hp merc. He uses it as a commerical crabbing boat. He cut a hole in the floor so he can tilt it when in shallow water. No, I don't have picture's.

 

[hoytvectrix]

Re: Yamaha jet drive on a toon?

I run a jet drive on a jon boat, but I found this on outboardjets.com, the company that makes the jet lower units for outboards:

"Pontoon boats don?t provide a defined height apron of water ahead of the jet intake. The water level between the pontoons varies with speed and load carried. It?s necessary to build an inclined plane ahead of the jet intake attached to the motor mount, about 16? wide inclined at about 15 degrees with the leading edge above water level, fully loaded at rest, trailing edge lined up with the leading edge of the jet intake."

You can run a jet on a pontoon if you get it rigged right. And as said above, there is a 30% loss of power

 

[PGFISHER]

Re: Yamaha jet drive on a toon?

A 250 HP jet ski puts out 1000LBS of thrust to push a 1000LB boat to 60MPH. The problem with a toon is that it isn't a planing hull and 1000LBS of thrust won't be enough push. Doing the math, a 60HP outboard comes out at 1850LBS of thrust. A toon would need an awfully big jet.

 

[J Hartman]

Re: Yamaha jet drive on a toon?

Has anyone heard of running a jet drive outboard to a pontoon? I was looking at motors and these caught my eye ( I have young ones ).

Well, I guess it comes down to how much money you have, how much money you plan on spending, and if your income is residual. . . lol

Reasoning: Outboard Jets are
1. More expensive on the Front-end
2. More expensive to Operate (ex. 35% more fuel consumption)
3. More expensive to get repaired.

Now, as far as being on a pontoon. Yes it is possible, have I ever seen it, No. Will I ever see it? I hope not. A pontoon is not a "planing" hull, it is made to PUSH water, not so much ride on top of it ex, flat-bottom. Your going to lose a lot of power by using an outboard jet, and need a TON more power to get the same result as a much smaller proped outboard. You lose right at 35% power when you put a jet pump on a normally proped outboard. 60 hp engine (assuming its rated at the prop) will be 60 hp at the prop, and only 40ish with a jet-pump... any hp just multiply it by .35 and you'll see what your really ending up with a 150 proped outboard is only around 98 hp with a jet pump. (I'm sure your getting the idea) Also a big issue with running a jet on a pontoon would be cavitation. I can see that being a big issue, and getting the height of the engine correct could also mean additional fuel consumption on top of your already 35% loss. It just doesn't seem logical to put a jet on a pontoon because as said before they are made more for skinny "shallow" water boats.

You said you have young ones. I'm assuming your afraid of having a prop in the water while your kids are swimming or something? I would just say, never have the outboard running while any of your passengers are "overboard".

All in all, i think you'd be a lot happier boater if you went with a proped outboard.