Is it feasable to build jet jon

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phil6092

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I have been looking through all the jet jon builds and was just wondering how well they hold up in the long run. I would love to build one but I am unsure if it would work in the areas I fish in. I mostly fish in back waters where there is a bunch of falling trees and such in the water. I realize I could build one just to cruise in and coolness factor but I am always tight on funds so it would have to be able to be fished out of. If some of you that have built one could chime in I would love to know if the jet jon is as durable as an outboard jon.
 
IMHO a correctly built jet jon will last as long as it is maintained and not abused which is pretty much the same statement you can make for any other boat out there.

Per the swap itself, material fatigue and corrosion are the two largest failure points which are difficult to design and build around. It's a boat, it vibrates. Vibration leads to metal fatigue. How the hull and ski joint is designed will be a huge determining factor on how long the hull lasts. Corrosion is a more subjective issue. Sealing corrosion between layers of exopy, glass, or other layers of aluminum is a time bomb waiting to corrode apart. Anything electrical will also corrode so sealed joints and keeping the boat as dry as possible is important to keeping the green death at bay.

I expect my hull will outlast me. I did as good a job as I could to keep the hull maintainable and it stays in my shed when not in use.

Hope this helps.
 
There are jet johns, and then there are real jet johns.

By that, I mean that just about anyone can cut a jet ski hull and slap it into a johnboat hull. However, proper hull/material selection, and proper construction will determine if it stands the test of time.
 
I had my first one built its welded you can see it in my signature at the bottom. I've ran into banks, trees, rocks, and sand bars the boat is holding up as well as any alumina craft hull would maybe better since more of its welded now. Some jet skis come with metal pump tunnels if you get one of those you can just cut the hole for the pump intake and discharge and then using a metal brake bend some thicker sheet aluminum into mounting brackets for the motor and either have them welded or bolted in that way you don't have to cut the bottom to glue in a jet ski hull and all that mess.

If you can do a lot yourself you can easily pick up a used Yamaha 701 or 760 that come with metal tunnels for about $1000 in working condition that will have everything you need motor, controls, pump, carbs, fuel lines, etc. all you need is a hull.
 
I agree, the bolt-in aluminum pumps are far better to use. If for some reason you ever have to replace the duct, you simply cut the sealant/adhesive bond around it, pull it out, and install a new one. With a spliced-in type, you have to find another hull to cannibalize, and then you have to do all that cutting.
 
Feasible? That word can have different meanings to different people, for me a jetjon was feasible because I fish shallow rocky clear rivers and thats pretty much all I have other than the Ohio river. If I was a lake fisherman then a jetjon would not be feasible solution to a good fishing boat. You mention stumpy tree filled waters, in that scenario a jetjon would be fine since there isnt a lower unit hanging below the boat waiting to be knocked off. If your water is muddy and debris filled then an outboard would be a better alternative than a jet pump (think of a pump as a water vacuum).

As far as build design goes, I agree that a weld-in aluminum pump is superior to a cut and splice fiberglass install, however....not everyone has the tools or know how to weld or for that matter the availability of an aluminum pump housing (only specific models have this aluminum design). For a first time build for grins and giggles then I would suggest a splice and glue method detailed on this site in many posts. This way you can utilize the pump, engine mount and exhaust setup in the existing ski without having to fabricate a new design, and the cool part is, IT WORKS GREAT. Time will only tell how long these builds will last but suffice it to say they work well to get you out on the water for cheap. My next build will be a more permanent weld in on a nicer hull, but for the little money I have in my jetjon, I couldnt go out and buy a decent outboard fishing boat. So to summarize, yes a jetjon is feasible and very affordable if you can buy the parts right, however the real cost comes in time sacrificed getting the thing built correctly...they are fun but very labor intensive.

Good luck, you came to the right place for info there are a quite a few guys on here that definatley know their stuff.
 
I thank all of you for the replys. I think I would like to try the all aluminum method is the yamaha's listed the only models with aluminum tunnels or are there other models with them. Also for the hull which works better wide or skinny hulls?
 
I was considering it just this year and decided to go with an outboard jet engine instead. I didn't like the idea of taking such an investment hit by hacking up a jet ski. Obj engines seem to hold decent value. Plus I can insure it. I don't know about insurance on a modified jet ski Jon.
 
I sent my insurance co pictures of my build. They didn't have any problem insuring it. The premium is about $30 per year.
 
Don't know all the year models that have the aluminum pump housing but I've got 3 skis two 760 which are 90 hp and one which is a 650 at 50 hp they cost me about 2k for all three one 90hp out board jet would be thousands on its own and way 200+ lbs my ninety I picked the motor up and set it in my boat myself bet it weighs about 100lbs
 
There are many ways to do it but this is how my first one was done and I've invisioned how to do it without much welding or any at all you could even do it like this on a seperate piece of sheet and just rivet and bolt with some added 5200 sealant the motor skid to your hull or use square tubing and bolt that to the hull for the motor mounts many ways to do it either way use stainless bolts and 5200 to seal.
 

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The first picture has a crude drawing of if you bent a bracket with a metal brake bolt the lines but I think square rubing could be bolted just as easy with no bending just cut to size.
 
It's like building your own toy, & you can keep improving it over time. Definitely start with a quality hull.

I would go with the yammie aluminum setup if I was to start over. Pop rivets work too.
 
amk, I like the way you installed your intake duct where the back end butts up through the transom.

When I did mine, I rolled a horseshoe-shaped ring, and wrapped that a few inches farther ahead on the duct. It still works as intended, but your method sure looks a lot quicker and easier!
 
AMK your boat looks awsome I wish I new someone with skills like that. How fast will your boat run with the 90hp motor? Also did you have to add a spoon to the front of the pump?
 
No spoon I never had any cavitation I did go through a couple aluminum impellers before I found ss impellers were the way to go. The first motor I had was a 50 it pushed me max 30mph under load was about 26 then I got the 90 hp with minor modification it fit right in and now I can touch 38 with moderate load it's amazing how much difference it made. 38 in a 16ft jon boat is ridiculously fast. I have yet to be in another aluminum boat of that size that is powered to get anywhere close to that.
 
It just seems to me that people who cut the bottom of a jetski out and glass into the hull have the spoon issue I did that to a 12ft boat and it has some minor cavitation on top end but I haven't really ran it much because I have my 16ft that's been keeping me pretty busy.
 

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