Cataraft Frame Depth - Mountain Buzz
 



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Old 05-13-2012   #1
 
Love2fish's Avatar
 
Boulder, Colorado
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Cataraft Frame Depth

I just picked up some used El Tigre 28" tubes and am in the process of designing a frame. I went to Down River (Love those guys!) and Mike recommended a drop of 16.5 inches so that I could get a big (21.5 inch tall) cooler under my seat and basically everything else down low. Jacks suggested I keep the drop at 12 or 13". I know everything is dependent on load and I am going to take this on the Grand, so it WILL be loaded, but... how do I reconcile this discrepancy? the tubes are a nominal diameter of 27.5", so a drop of 16.5 leaves 11 inches of draft? I know that keeping the frame out of the water is hugely important, so any advise will be much appreciated

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Old 05-13-2012   #2
 
TOUCHDOWN, Mississippi
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I have nearly the same cat

But aire lion tubes, not JPW. I got my boat used, and it came with a full diamond plate floor, double rail diamond plate, 12' long frame. From the top of a cross rail to the floor is 13", and I wouldn't want the floor any deeper than that. I've yet to high center it, and have no interest in doing so.

That includes an overnighter August trip on browns gear boating for 15 people, and two passengers last summer.

I don't think I would want any less clearance underneath.
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Old 05-13-2012   #3
 
Walterville, Oregon
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How far down the tube are the inside d-rings? How will you attach the the frame to these d-rings? Do you mind if your tubes are canted a bit? If you can answer these question you can figure the maximum drop to have in your frame. Looking at it from the perspective of draft is bassackwards.

Me - 30 inch tubes and 14 inch drop, but I was limited by the placement of the inside d-rings. I like the clearance, especially on low rocky rivers where I can straddle rocks. The higher center of grqavity has not been a problem on the Grand.
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Old 05-13-2012   #4
 
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Boulder, Colorado
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I measured the D-Rings (while they were perfectly horizontal) at 10" above the garage floor. My pref would be not to "cant" the tubes but I haven't yet figured out how the attachment will happen... I've never owned a cat before and thus never rigged one. I assume with the D rings being so low, even a 16" frame would allow me to cinch it downwards. Anyway, not sure why Down River would recommend such a long drop when the manufacturer does not. Both clearly know their stuff!
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Old 05-13-2012   #5
 
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vancouver, Washington
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Make the frame a bit wider so the cooler can drop between the drop rails. 13" or so is about as low as I'd go on a frame unless I knew I would only travel deep wide rivers with zero chance of highcentering
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Old 05-13-2012   #6
 
flagstaff, Arizona
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go to jpw web site and review their draft vs load chart. I have the discontinued Grand Daddy cat tubes. My drop is about 12 and am thinking of shorteneng it a little as my deck was awash for a few days after launch. Course I am told I take too much beer. (is this possible?)
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Old 05-13-2012   #7
 
Jenks, Oklahoma
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I had a bomber frame made for my Aire 18 Cat and recommendation on frame depth came from same guys.

I ended up making another frame. Big problem was a heavy load on that frame and water came in over the front of the frame and I used a plywood floor which made for miserable performance in big water when I needed to make a move.

My advice is put a frame sized tube across your pontoons. Measure down from the bottom of the cross rail on the tubes to the top of the Dee rings on the inside of the tubes and allow your self a couple inches more clearance for the straps. The more clearance between bottom of frame and the water the better in almost all instances.

Wide frames are the bomb as well unless you are doing narrow creek runs.

Jack knows his stuff on cat frames and I would listen to him over any one else.
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Old 05-13-2012   #8
 
Walterville, Oregon
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Quote:
Originally Posted by Love2fish View Post
Mike recommended a drop of 16.5 inches so that I could get a big (21.5 inch tall) cooler under my seat and basically everything else down low.
Why do you want the cooler under your seat? The El Tigre is so big there are lots of other places for it.
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Old 05-19-2012   #9
 
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Boulder, Colorado
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Much appreciated!

I appreciate all the feedback and I'm leaning pretty heavily towards a drop (top of frame to bottom of frame) of 14". I've moved the cooler to the bay in front of the cockpit and put the drybox under the seat. The thing that's driving the depth more than anything is the front bay. It's going to be on the order of 36" long and will have a drop hatch/ sleeping deck on it. Subtract the dimension of one frame tube (1 7/8 and 5/8 for a plywood bottom deck and the hatch only allows 11.5" of stuff underneath.

Oh btw, sleighr recommended looking at JPW's load chart. With 12", they show 2683lbs. Seems like a decent amount...





I'm not sure yet what's going in the front hatch and would love some feedback on that! Where do you folks carry your water on a big cat? I reckon the drop hatch will get covered with a fair # of drybags/ pacos, etc to make it comfy for the passengers... And finally (maybe), I've attached a diagram of what I'm envisioning.
Thanks again!
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Old 05-19-2012   #10
 
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portland, Oregon
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Quote:
Originally Posted by Love2fish
I'm not sure yet what's going in the front hatch and would love some feedback on that! Where do you folks carry your water on a big cat? I reckon the drop hatch will get covered with a fair # of drybags/ pacos, etc to make it comfy for the passengers... And finally (maybe), I've attached a diagram of what I'm envisioning.
Thanks again!
if you are carrying 20 gal of water that is 160lbs. I would say try and get most of your mass towards the center to make it easiest to turn that beast. That means see id you can find space in your cockpit

Water jugs are a lot more gentle on your legs then say a set of captains boxes. If you alrady have that space allocated see if you can find jugs that fit in the nooks aside the cooler/drybox

Be careful with jugs that have a pop out plastic vent. They often pop out on their own and leave you with less water to drink
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