JetJon Conversion - SeaDoo SP into 1236 Fisher

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painlesstom
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by painlesstom » 05 Dec 2012, 10:58

New member here, so hello to everyone.

Long story short, I've spent the past year coming up with solutions to problems with the Mokai jet boat and now that I've accomplished that and have nothing left to do but use mine, I got pretty good at fishing for Catfish. Now I want a little bit bigger boat so I can catch more, go faster and farther, while having the option to take a friend along once in a while. I prefer jets since my river has shallow parts, and lots of fallen trees etc..

So I started planning my FrankenJon boat.... And the adventure has begun.

These are some of the pictures up to my current progress, I look forward to everyone's comments. :mrgreen:
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JMichael
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by JMichael » 05 Dec 2012, 15:25

Subscribed. I love to watch the progression of unique projects like this.

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painlesstom
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by painlesstom » 07 Dec 2012, 19:23

Made some more progress. Finished laying down the fiberglass and got the motor and pump installed.

Since I planned on using the stock Seadoo steering helm, I took an old set of drag bars from my Harley days and cut them in half to make my steering stick. Perfect length and a nice slight angle forward.

Problem came about since I am mounting the steering assembly backwards from it's original orientation made the steering response opposite.. So I had to pull it all apart and re engineer the whole assembly so right is right, and left is left. Made up an aluminum brace to tie the bracket back together.

Steering stick will use the stock Seadoo throttle and I'll be adding a momentary contact thumb switch on the end which will start and stop the motor.

Still haven't decided where I want to put the fuel tank, so many different ways to skin a cat....

Seat is balanced for the picture, but pretty much where I intend on mounting one.
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JMichael
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by JMichael » 07 Dec 2012, 19:39

How many HP is that motor and what sort of speed do you expect out of the boat when finished?

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PSG-1
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by PSG-1 » 07 Dec 2012, 21:12

Nice work, sir! :mrgreen: Don't know how I missed this when you posted it a couple of days ago, but anyhow, here I am!

I always enjoy reading these jet jon threads and seeing photos. Looks like you're doing it with no welding involved, and that makes this a good informational thread for those who want to build jet jons, but may lack the welding and machining equipment.

As to the question about the engine, it appears to be a 717 cc Rotax engine, like what is used in the speedster jetboats. With that engine in a 12 foot boat, you should see speeds of around 40-45 MPH, maybe even faster, as that boat is pretty lightweight from all appearances.

Keep us posted, and if you need any info as to control cables, or even how to make a weedless grate, check out my aluma-jet build.
ALUMA-JET project:
http://www.tinboats.net/forum/viewtopic ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

http://www.youtube.com/user/HKPSG1Shooter?feature=mhee

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painlesstom
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by painlesstom » 08 Dec 2012, 01:31

Thanks. Between bolting everything together with 30 stainless 1/4-20 screws using polyurethane, and reinforcing the whole area with fiberglass, I am confident there won't be any leaks or movement to alloy any to develop.

The motor is the small 587 Rotax, 55 hp. I'm not worried about warp speed, 30-35 mph is what I'm expecting to see, I probably will only cruise at 25 anyhow. Less power usually equates to lower maintenance, longer life, and better fuel mileage. Time will tell, as always.

I will be using aluminum angle to frame out over the engine area for a 1/2" plywood deck, the fuel tank will probably get mounted inside what was the middle bench. That will help keep some weight forward. So far, I would be willing to bet the entire boat is still lighter than the jet ski was, before I chopped it up.

PSG-1, I have looked at your aluma-jet before, nice job. I thought I started with a rough Jon, you brought yours back from the grave!

I have welding and machining capability, I just don't have the means to weld aluminum. The aluminum angle for the frame work will get bolted together, makes things easier if engine work is later necessary. So what I'm doing can be duplicated by anyone with a sawzall, a drill and a tape measure, with regards to joining the two hulls together anyhow. Measure three times and cut once...

I'm still contemplating the need for reverse, not sure if it would be worth the effort yet. It comes in handy on my 14' Sea Rayder w/ sport jet 90, it's also a much bigger and heavier boat though. Some feedback on this would be appreciated from those who have built one of these boats.

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PSG-1
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by PSG-1 » 08 Dec 2012, 10:59

painlesstom wrote:Thanks. Between bolting everything together with 30 stainless 1/4-20 screws using polyurethane, and reinforcing the whole area with fiberglass, I am confident there won't be any leaks or movement to alloy any to develop.

Sounds like a good plan, build it good and strong. As long as it's done this way, the cut-and-splice method works, and saves a LOT of time, when compared to the all-out fabrication method like I used to do my boat. I shudder to think of the total hours I spent on my boat :shock: My girlfriend was starting to get jealous of the boat for a while. That is, until she rode in it, and saw how much fun it was...almost like the 14' Sea Doo speedster we used to have, but better!



The motor is the small 587 Rotax, 55 hp. I'm not worried about warp speed, 30-35 mph is what I'm expecting to see, I probably will only cruise at 25 anyhow. Less power usually equates to lower maintenance, longer life, and better fuel mileage. Time will tell, as always.
Heck, I didn't know they made engines smaller than the 717. But based on that, yeah, your estimate of 30-35 MPH is about right. One good thing about the smaller engines is that they are easier, and much less expensive, to rebuild. Not to mention being light enough that 1 man can install or remove it by themselves, without too much trouble.


I will be using aluminum angle to frame out over the engine area for a 1/2" plywood deck, the fuel tank will probably get mounted inside what was the middle bench. That will help keep some weight forward. So far, I would be willing to bet the entire boat is still lighter than the jet ski was, before I chopped it up.

Probably so, and that's a good thing, too. While I love my jetboat, fact is, that sucker is HEAVY, like 1200 lbs. So, if I screw up and ground it, I'm not going to be able to drag it off by myself, or even with the help of someone else. Which is why I carry a come-along and lots of rope when I go on the narrow inland rivers. That way, if I make a mistake, I can hook to a tree, and winch myself off the shoal. Never had to do this yet, and hopefully never will, but there's always a chance! So, this is where a lightweight jetboat comes in real handy, especially when exploring unknown areas that don't have much traffic.




PSG-1, I have looked at your aluma-jet before, nice job. I thought I started with a rough Jon, you brought yours back from the grave!

Well, thank ya! :mrgreen: It was a labor of love, to say the least. But worth every bit of it.


I have welding and machining capability, I just don't have the means to weld aluminum. The aluminum angle for the frame work will get bolted together, makes things easier if engine work is later necessary. So what I'm doing can be duplicated by anyone with a sawzall, a drill and a tape measure, with regards to joining the two hulls together anyhow. Measure three times and cut once...

I'm still contemplating the need for reverse, not sure if it would be worth the effort yet. It comes in handy on my 14' Sea Rayder w/ sport jet 90, it's also a much bigger and heavier boat though. Some feedback on this would be appreciated from those who have built one of these boats.
Reverse is nice to have. Not just for reverse, but if you like to fish by trolling, the reverse gate works like a trolling plate on an OBM, only, the range of adjustment is infinite, from full ahead, to full astern. Also, it's nice for when you come in to the dock, or you're trailering the boat, so you can 'crab' the boat into position, instead of having to cut the engine off right before you get to it, then scramble to keep from hitting something.

If your jet pump is not equipped with a reverse gate, don't worry, you can get one that mounts onto the ski/boat, instead of mounting to the jet nozzle, like mine is. You'll want the reverse gate from a Sea Doo Speedster jetboat, or something like what's used on the Yamaha VX110.

All you have to do is make a set of brackets that come off the hull, for the gate to mount to, then, run a Teleflex CC633 series control cable, and make a shift lever like the simple levers used on my boat.

Hope this helps!
Last edited by PSG-1 on 08 Dec 2012, 15:38, edited 1 time in total.
ALUMA-JET project:
http://www.tinboats.net/forum/viewtopic ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

http://www.youtube.com/user/HKPSG1Shooter?feature=mhee

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painlesstom
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by painlesstom » 08 Dec 2012, 12:27

I'd thought about using the nozzle from a Yamaha SJ650 which has a reverse bucket, adapting it to the Seadoo pump wouldn't require too much work. When I asked about opinions on reverse, I didn't even think about having neutral, something I've taken for granted. I make a clutch for the Mokai jet boat, so when I let off the throttle the pump stops (air cooled motor). Since I won't have that option in the jet jon, a reverse gate is going to be a must as neutral is a necessity for me. I've got the complete Yamaha nozzle, also have a few jet ski's I got to part out. So cables etc.. I have in abundance.

As far as motors smaller than the 717, Seadoo also made the 657 in addition to the 587 I have. I also have a '95 XP with the 657x with dual carbs and VTS.

Forgot to post the chop chop video of my donor Seadoo. Enjoy ;)


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PSG-1
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by PSG-1 » 08 Dec 2012, 15:36

Cool video! Brings back memories of when I started on my jetboat, way back in 2005.

I also checked out a couple of your other videos in the mokai....that is a cool little boat right there! :mrgreen:

Now ya got me thinking on my next jetboat, maybe I should build something smaller, instead of bigger or equal to what I have. I'd love to have a small lightweight, haul-ass jetboat that's about like a jet ski, small and light enough one man can beach it and drag it off, yet, it has the advantages of a boat, like being able to ride and stay dry.

Something like a jet ski kayak or canoe is what I'm thinking, in fact, we've tossed that idea around.

But maybe with an aluminum hull, and UHMW plating to make it seaworthy for the fall line and farther inland on SC's rivers, instead of plastic or fiberglass.

I own a Yamaha Superjet (stand up jet ski) but my sciatic is getting so bad, I can't have fun on it like I could when I was 20, if I have fun, I pay for it with pain for a few days.

[eyeballing SJ from across the yard, looking at recipro saw] "Hmmmmm." :mrgreen: :mrgreen: :mrgreen: :mrgreen:

Nah, I don't think I can bring myself to do it, the ski is in too good of shape, not a stress crack anywhere, and that's EXTREMELY rare for me, I break every jet ski I own.

BUT, I think something like the SJ (engine size-wise anyhow) would be a good candidate for a project like that. Or maybe even an old Kawasaki 550, there's tons of those floating around.

I see another jet project in my near future.................
ALUMA-JET project:
http://www.tinboats.net/forum/viewtopic ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

http://www.youtube.com/user/HKPSG1Shooter?feature=mhee

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painlesstom
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by painlesstom » 10 Dec 2012, 20:00

Steering helm conversion has been completed and securely mounted. It now operates backwards from it's original position and I'm glad that part is done...

Deck frame work is almost completed as well. I will be using 1/2" plywood and it will be one piece hinged at the rear so It can function as a hood as well. The center area over the motor will have a separate cover I'll be making from fiberglass which will also be on a hinge with a latch, it will be attached to the deck so it will follow the deck when opened or it could be opened by itself.

Fuel tank is going to be mounted where it's seen in the picture. I will be building a console that will cover it and give me a place to put my filler cap, GPS, cupholder, windshield etc..

PSG-1 - The Mokai is the ultimate for getting to otherwise inaccessible areas. It's light, air cooled, the pump can be removed with no tools for cleanout. It's not going to break any speed records (12-15mph), but it will sip fuel like nothing else you own. I get roughly 25 mpg, and the tank is just shy of 3 gallons. I get many fishing trips out of a tank.

Let me know when you start your next jetboat.
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by painlesstom » 14 Dec 2012, 01:20

Started planning out what I want to do with the deck area. Haven't decided if I want one big cover on a hinge with a smaller engine cover attached with it's own hinge.. or if I'm going to split it up so each side, rear, and engine cover open independently.

Started work on the console and got it mounted to the seat. Need to get some Lexan to build the windshield next. The floor under the seat is housing the fuel tank, I put 3 layers of fiberglass down to reinforce that area so the fuel tank is better protected and put a thick rubber mat under the tank so there won't be any concern about rub through. Will use the rubber hold down straps to secure it along with the oil tank.

It's getting heavier, but I can still pick it up, so it's staying within expectations so far.
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by PSG-1 » 14 Dec 2012, 09:02

It's looking good! Cardboard is a great item for doing mock-up work, as shown in the photo where you're working on the cowling/rear deck.

The access to the engine can be done either way you're talking about. It's really a matter of personal preference. If it were me, I'd make it a one-piece lid. Then it should be strong enough to stand on it.
ALUMA-JET project:
http://www.tinboats.net/forum/viewtopic ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

http://www.youtube.com/user/HKPSG1Shooter?feature=mhee

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painlesstom
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by painlesstom » 17 Dec 2012, 00:55

Thanks, cardboard is the lazy man's tape measure. lol One piece deck made more sense to me too.

More finished on the console, starting to look like something I can mount a windshield to. The top of it I made from HDPE, as well as the bracket for the oil filler neck. Got the deck cut out and the hinge mounting planned. Little bit closer. Would have gotten more done, but had some fishing to indulge in.
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JMichael
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by JMichael » 17 Dec 2012, 03:44

Is that a 2 cycle motor with oil injection or is there some other purpose for the oil tank?

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PSG-1
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JetJon Conversion - SeaDoo SP into 1236 Fisher

Post by PSG-1 » 17 Dec 2012, 09:52

Starting to take on some shape, now! Looks good with that rear deck, that'll be a great fishing/casting platform. 8)
ALUMA-JET project:
http://www.tinboats.net/forum/viewtopic ... 21&t=22023


Fishing, jet skiing, target shooting, jet-boating, and even a little oyster harvesting with Larry The Cable Guy.
Watch it all right here:

http://www.youtube.com/user/HKPSG1Shooter?feature=mhee

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