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Discussion Starter #1
Hello all

I am building a motorized cataraft soon using AIRE Jag tubes. I have an old NRS frame that I will piece together as a prototype setup, just to see if i can get the idea to work. I have a 20 hp honda four stroke outboard as well. I have been making considerations for a planing surface and will most likely be using UHMW polyurethane sheeting due to its extreme durability for all decking and planing boards. Tricky part will be the transom motor mount. Any suggestions are welcome and much appreciated.

Thank you
 

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My uncle runs an Air jag with a minn kota c2 40. I'm trying to envision the transom, but I think he just u-bolted 3/4 marine ply to a drop/kick bar from NRS, pretty simple I believe.

Now you are talking about using a raft frame, I assume you are adding drop rails? You might be able to find a way to mount NRS's "raft motor mount" to your existing frame to make it usable, although I would guess it would need some support from the bottom.

The NPS uses some "jet-cats" I call them around here....but they all look like fully custom frames, but are really bad-ass!
 

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I'd consider a "jersey skiff" style design for your motor location- the Jag tubes are so rockered that I think you're going to get a hell of a lot of bow rise if you place the motor at the stern. The other issue is going to be steering- without a keel or chines it is going to be hard to get that boat to turn....at all.

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Discussion Starter #7
I tried to research jersey skiffs but didn't find much. Does that mean the motor is moved forward some to protect it? I wouldn't have the transom up into the tube rocker. It would be at the end of the tube tangent before the upward curve.

Would the tubes not act as keel/chines somewhat? I feel like a cat's design gives it the ability to track water current pretty well.
 

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That is correct- jersey skiffs have a pocket in the hull which contains the outboard engine- on your cat the location would be as far forward as you could reasonably place the engine from the rockered section of your tubes.

When you row your cat hard and then stop rowing and coast, it will start to spin after a short time, right? Look at a Hobie cat by comparison- it has hard lines below the water- but even then, they have added dagger boards to aid tracking on the latest ones. I don't believe you are going to be able to steer when on plane without adding some sort of keel.....but that's half the fun of messing about in boats- you don't know until you try.

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Thanks for the input. What is the NPS and how big are these jet cats? Boat length and horsepower
National Park Service and I'd say Philip was right on his 16'X22". The engines....can't say for sure but I'd say a 40 or 60 hp jet. They aren't small and allow them to run upstream through class IIIs. I also used to see a shorter, 13ish foot hyside with sponsons (I think they are called, mini, secondary tubes on the inside of the maintubes for more displacement)
 

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Discussion Starter #10
Thank you guys for the info so far. It's cool to know people have been running jet cats. I have some pretty interesting ideas for motor-raft designs, just need to get a working prototype together and get it out on the lake to see what happens.

Any more information about these National Park Service jet cats would be appreciated. Does anyone know about their floor design? I'm curious what's in between the pontoons as far as: distance between tubes, planing surface, distance from floor to water/bottom of tubes, tube fins and/or tube shape, raised bow etc. Do the motors have tiller handles or linkage and steering wheels?

Thanks again
 
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