Turbo Jet Jon!!

[airbornemike]

Bad ***, I need a second boat :twisted:

 

[Ranchero50]

Just tossing around the idea of leaving my tunnel in the boat and putting the jet intake on the tunnel. I know this will make me have to mount the engine higher in the boat and jet pump higher on the transom. Any thoughts on this idea guys. I know the advantage will be sucking up less rocks and sand in extreme shallow. Disadvantage will be a loss of speed as it already lost me 7 mph. Thoughts guys??

The longer the pump inlet, the harder it is to draw water. I'd remove the tunnel and mount the pump as low as possible inline with the bottom of the hull. Oh yeah, the spoon is the bubble looking thing on mine. It works wonders to help curve the water up into the pump inlet while pushing the air to the sides of the inlet.

 

[mr_hypno]

Just tossing around the idea of leaving my tunnel in the boat and putting the jet intake on the tunnel. I know this will make me have to mount the engine higher in the boat and jet pump higher on the transom. Any thoughts on this idea guys. I know the advantage will be sucking up less rocks and sand in extreme shallow. Disadvantage will be a loss of speed as it already lost me 7 mph. Thoughts guys??

The longer the pump inlet, the harder it is to draw water. I'd remove the tunnel and mount the pump as low as possible inline with the bottom of the hull. Oh yeah, the spoon is the bubble looking thing on mine. It works wonders to help curve the water up into the pump inlet while pushing the air to the sides of the inlet.

Thanks for your input. I was only going to keep a couple inches of tunnel depth just to keep my intake from sucking up debris so easily. I have already made some initial cuts in the tunnel for what I was thinking. I do have some pics and will post them later and see what you think.

 

[Ranchero50]

I'd get rid of all of it and ad a decent shallow spoon onto the front of the inlet. At the speeds you'll be running you not have problems picking up trash but you will have troubles with air ingestion. Only about the last 5' of my hull are in the water at 45+, the pump inlet is @ 3' from the original transom. The spoon helps keep the pump inlet drawing water vs. chunks of air. When I go over weed clumps at speed the hull is going too fast for any trash to draw into the pump. At low speeds I've had troubles but not at WOT.

Oh yeah, for your cables, just move your driving station to where they will work. I had to run a shaft to the bottom of the hull for my steering but the throttle cable was long enough to reuse.

 

[mr_hypno]

I personally think its going to work with of course some tweaking and tuning. What inspires me is SJX jet boats. They have a inboard jet tunnel and it must work or they wouldn't build it. Im sure it took a lot of development to make it work. Im willing to spend the time and make mine work as well. The benefits outweigh the downfalls for my situation.

 

[gotasquirt]

I am jealous you have a Honda power plant the way that I set my jet units up is I set the intake as far back as possible if the hull has a small v at the transom put a pad in the hull about 4 foot long start at the keel level and make it just wide enough at the transom for the pump to sit flat no need for a spoon you might want to take a look at the nz jetboating forums I have built 5 jet jons from a 701 Yamaha powered to a 250 hp Kawasaki super charged boat if you want you can email me with questions will

 

[mr_hypno]

Sorry guys!! I havent been updating on here like I should. Progress has been made in baby steps though. I downsized my tunnel to 1 1/2" tall. Got a start on my jet intake. What a tedious and time consuming part to build!! I didnt do jack squat over the winter on it...negative 20 degrees will make a guy hibernate!!! But im back on task now again and slowly working away at it. Update pics to come.

 

[mr_hypno]

The calm b4 the cutting storm!!

 

[mr_hypno]

More looking and thinking :wink:

 

[mr_hypno]

old prop tunnel

 

[PSG-1]

More looking and thinking :wink:

Building a jet john, you will have a lot of these moments. One thing I learned on my boat, is that it's better to 'ride by and look at it' twice, and only have to do it once!

 

[Ranchero50]

Ditto, 90% thought, 9% scrounging for parts and 1% action.

 

[PSG-1]

Ditto, 90% thought, 9% scrounging for parts and 1% action.

Mine was more like 75% thought, 10% waiting on ordered parts to arrive, 14% modifying parts that didn't work, and 1% action. :mrgreen:

 

[CedarRiverScooter]

My allotment included many test trips on the river, actually the fun part. Improvements are still happening!

 

[mr_hypno]

This was my original plans for keeping the tunnel. Everything above the sharpie line must go. From the back u can see it wasnt a very even cut lol :roll:. I forgot how my tunnel wasnt bent exactly straight. And the idea evolved from there.

 

[mr_hypno]

I decided that the engine was going to be way too high so again i cut more of the tunnel out. Ever evolving design!!

 

[brianb2247]

Keep it up when I was building mine id lay parts in for ideas, are you making yo jet pump aluminum or are you glassing it in

 

[CedarRiverScooter]

I used cardboard, foamboard & duct tape to mock up the layout. This worked well particularly for ergonomics of controls & seating.

 

[mr_hypno]

Jet intake will be all aluminum. Difficult to build but also easy to transfer into a different boat. This is more like a test platform before I buy a brand new 1752.

 

[Ranchero50]

I wouldn't sweat the transfer. Once you build one, you'll have the skills to modify the setup for another hull.

One word of advice, keep the inlet as close to the transom as possible. Less chance to induce air. Less chance for cavitation in the tunnel. Easier to clean.