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I'm looking to have a custom Cat. frame built and don't have a frame to base it off. the two major dimensions i was wondering about were the distance between the the foot bar and the seat bar. I know this is going to differ from boat to boat and person to person, but some numbers would be great. The other dimension I was wondering about was the the distance from the vertical brace on the inside of the tube to the outside edge of the frame that sits on the tube. If you know some of these number it would be great if you could post them.
 

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no tengo
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measure your inseam and subtract a little for the foot to seat.

for the outside to vertical brace just take the tube diameter and cut it in half and add an inch or so.

nrs makes a 'retro' frame that is adjustable. for smaller cats you can specify a smaller rail length and cross bar widths.

you didn't mention your tube size.
 

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Discussion Starter #3
thanks for info. i have tubes with a 22in diameter and 15.5 long so the top brace length would be 12 inches and what ever length i wanted

any other ideas out there?
 

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My fame is full tilt custom, both cat boat and round boat. I made my captains bay a little smaller, to fit the rest of the big stuff Big stuff....

not sure about tubes, either, and also agree with mania, about the retro cat bars.....basically you have a raft frame, and can add the verticals" (retros) and you have a cat frame

also see

NRS Cataraft Yoke
 

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no tengo
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I like the 6061 or 6063 aluminum schedule 40 that NRS uses. seems to be strong enough and is about as light as you can get. DRE will dispute this and uses larger diameter aluminum.

steel is great but is heavier for the same diameter, not as cheap as it used to be and could rust unless you coat/paint it. its easier to bend/weld.

check this out: MADCATR Creations - Custom Fabricated Stainless Steel and Aluminum Rafting Equipment
 

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aluminum vs. steel tubing

In the 'Similar Threads' box below there's a listing for 'Games with Frames' where I posted quite a lot of info (and some photos) on fabricating your own custom cat frames.

I use galvanized steel tubing (intended for chainlink fencing and called top-rail) that's 1.315-inch OD, which is as strong as the larger alu tubing in NRS frames while being about the same weight per foot. The corners and joints are Hollaender SpeedRail aluminum fittings, with the 1-inch size being right for the top-rail tubing. I've also used conduit ells, drilled and bolted, for corners.

The major design factor is to "box" your frame, i.e. have at least two tubing members in every direction where flexing might be a problem.

The two details I'd rate as most important:

a) drive plugs (hardwood dowel is good) 2 inches long at the ends of tubes so the setscrews in the joints won't squash them (also to keep water out).

b) File and sand off all the sharp edges— a rotary tubing cutter leaves nasty razor curves (drill holes likewise). Also, make sure none of the setscrews in the joints will bear against a tube.

The nice thing is that you can build a decent frame for around $200-300, and tweak it to perfection. It breaks down for winter storage or bush-plane transport (also for long-distance travel inside the vehicle).

If you're going to haul big loads on big water, say an 18-ft. cat with 28-inch tubes for a Grand trip, get a component-style frame from DRE or NRS. If you're running a sub-16 footer on III and IV water, a homebuilt frame will do fine.
 
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