Originally Posted by ob1coby
There is no way. Comparing the surface of a screw being tightened against the pipe to a ubolt that wraps around the pipe and tightens on both sides. There is no way that the clamp design can be as strong. the problem is defining the word "strong". Maybe the clamp will take 2k in "force" before breaking, but what kind of force are we talking about here. From an engineering standpoint you have Lateral, torsional, and sheer forces just to name a few but my biggest concern would be twist force and there is no way that screw can compare to a ubolt in any of them.
For me that means that I would not use them for building a cat frame where the frame provides the stability of the entire rig. BUUUUUUT I wouldn't really have a problems putting them on a raft frame where the frame secures to the raft and just holds... stuff. I might be nervous enough to check the crews regularly.
Thanks! sounds like you have some engineering background. I see the big difference between a cat and the raft and agree w you, the raft provides structure. The worst case situation is what my concerns are, ie, bad pin or violent big hole maytag style flip. I would guess a bad pin w thousands of pounds of hydraulic force is the worst situation, not sure any type of fitting, or even the frame pipe, would hold up to that kind of stress, given the amount of force of moving water?? Luckily, my boat has 4 huge D rings on each side and I use them all when securing my frame, that has to make a difference in distributing the load. I am betting that metal dry boxes tightly fit between the frame members do give some protection against sheer force, like sheathing on stick built construction.