Cataraft Yoke Placement? - Page 2 - Mountain Buzz
 



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Old 4 Days Ago   #11
 
Join Date: Feb 2020
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Quote:
Originally Posted by Tower Climber View Post
Oops, I plan to run mostly mellow SW USA silt highways but up to and including the Grand (would definitely not be running this unyoked front-most portion on the GC)....My concern is exactly what salmonjammer hit on...in event of collision the long lever arm of front tubes working to warp in the lower rails without a spreading lower bar...so maybe mix in or use instead the NRS (https://www.nrs.com/product/1806%20s...l-spreader-bar) - or some kinda homebuilt - lower spreader to keep the front of the lower rails spread out and the floor taught...


there is an interesting rear cat extension that is not (to my eye) a typical tail end yoke in Raftpron post 1466 (https://www.mountainbuzz.com/forums/...40045-147.html)
I think this is just going to take some experimentation. On your part and mine. There is at least one comment saying rigidity is not a problem which doesn't really make sense or they wouldn't sell that spreader bar you linked. When I stand on my mesh floor the the lower rails clearly flex so moving the yokes would help 100%. Another comment that didn't really make any sense was the one about packing. If I swap the position of a yoke for a crossbar it would have zero affect on packing. The only thing that I hadn't thought about and does make sense as a potential issue is not being able to strap the lower front of the frame securely to the foremost D-ring... maybe is there some solve for this.

And as for your platform idea I'm on the same page. Looks great for a mellow float but would not want to risk that anywhere rocky. That said dismantling your whole frame and moving the webbing around seems like a major pain in the ass. Maybe you could just move the front bench seat back so the foot rest is within the proper frame and then add something like this onto the back, I think you said you have a proportionately short frame for your tubes so that could fit in back easy. And actually that one looks a little over-engineered and pricey. There is someone that makes one that is sub $200 but I can't find it right now.

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Old 4 Days Ago   #12
 
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Poundtown, Wokastan
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You're way over thinking this one. If you're concerned about hitting stuff, get drop rails. Bottom line is, you'll want as much frame/floor as possible on a cat boat if your'e just floating the mellow to 3+.
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Old 4 Days Ago   #13
 
Grand Junction, Colorado
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cat frame setup

The yokes are placed where they are in the NRS cat frame pix to allow the rower to sit as far forward as possible and have a bomber foot bar. That is the Idaho style of cat-boating, where cats push forward into everything. You can change that by moving the front yoke back, but it changes the weight distribution more to the center. That is probably fine for up to class III.


I've had cats since 1993 and put thousands of miles on them over that period. The biggest issue, in my opinion, is that cats work best when they are lightly loaded. As you approach the tubes' weight capacity they start handling like pigs. Keep that in mind....Passengers are happier in oval boats which can handle the weight and gear better, unless its a huge cat with high weight capacity. IMHO


Jocelyn
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Old 4 Days Ago   #14
 
Join Date: Feb 2020
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Originally Posted by dirtbagkayaker View Post
You're way over thinking this one. If you're concerned about hitting stuff, get drop rails. Bottom line is, you'll want as much frame/floor as possible on a cat boat if your'e just floating the mellow to 3+.
Oh I'm way overthinking it for sure.
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Old 3 Days Ago   #15
 
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Wheat Ridge, Colorado
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Yeah, you don't want to be this guy:

Beaver Overthinking Dam
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Old 3 Days Ago   #16
 
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Quote:
Originally Posted by jonathono2000 View Post
Oh I'm way overthinking it for sure.
You're really not over thinking it. Best to think ahead and as you suggest perhaps experiment.

The further the yokes are apart the greater the likely torsional(structural) rigidity of the NRS frame. Imagine the extremes. First, imagine the yokes next to each other at the center of the frame(boat), then............. I motored a six mile open water crossing between Baja LA Bay and Guardian Angel Island in a frame that lacked sufficient torsional rigidity. In continuous up to 8 foot swells it got kinda scary. I firmed up that frame first thing after getting home.

Earlier I mentioned tube material. Properly inflated, a PVC cat tube is more rigid than a hypalon tube. I think you'd better be able to get away with moving the yokes inboard with a PVC tube.

For a cat, I personally prefer the rigidity/integrity of bent and swedged corners and drop rails for bigger water. Or a properly welded frame. (Not, to suggest that a NRS frame is not up to the task. We know they are.)
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Old 3 Days Ago   #17
 
Join Date: Jan 2019
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I have an 18' Aire leopard with NRS yoke frame. I run three yokes one on the front, back, and close to the middle. The total frame length is 12' and this modification was suggested by a friend running 20' Jacks tubes with a 14' frame. I have several crossbars on the top rail keeping it stiff, the middle yoke helps stiffen the bottom rail. If I wanted to save weight I could probably get similar stiffness with a bottom spreader bar. Also my main passengers sit at the very front on a dry box. I have a foot bar that comes out at a ~45deg angle to brace their feet. It is also super handy for climbing back into the boat.
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Old 3 Days Ago   #18
 
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Quote:
Originally Posted by salmonjammer View Post
The only problem I would see is with the lower frame sticking out in front of the yoke, you are putting a lot of stress on them if you hit something with the front or rear tube on an angle. But probably not an issue
This is the drawback I see too. The tube would be bending around the end of the pipes instead of the whole yoke, potentially puncturing the tube with the pipe. What do you plan to use on the end of the pipes to prevent this pinch and rub point?
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