Interesting craft to say the least! Apparently about 30 sets of these hard plastic cat tubes were produced and are now owned by various people associated with rescue agencies, their friends, and several river rangers. They are about 11′ 6″ long and are not round tubes, but oval in cross-section, measuring about 22 x 24 inches. They do have Leefield valves in the blunt stern end and can be inflated slightly to help hold their shape and add rigidity.
These things have run all sorts of water (including Class V Gore Canyon on the upper Colorado) many times and have some design features that could be adapted to regular inflatable catarafts such as high volume, large diameter tubes for weight capacity and extra flotation, blunt stern to avoid endos, high volume bow to float up out of big holes, etc. and are very durable due to their heavy plastic construction. One drawback is that they are much heavier than inflatable craft, especially our lighweight boats made by Sotar!
Having seen these things in action on the Cache la Poudre River at high water (including a run through Pineview Falls) I can say that they plow through some big stuff for their relatively small size. They don’t appear to be as surfable as the longer-tailed, more curvy inflatable designs that I like, but seem to be very stable in the big stuff. I wonder how long it will be until one shows up in California!