This hybrid aim to get the benefits of single skin to be safe on water seems commendable. I've been messing around with SS kites for a while. They have a lot of advantages - water relaunch not being one of them. My main interest is for kite boating. To this end, their scalability and rapid inflation (which term seems a bit odd for a single skin), which provides some good launch possibilities, are big (potential) advantages.
Christian, I'd not discount their strength or pulling power. Here is some video (
) of a 12m SS kite pulling a 130kg catamaran (Nacra 5.8 ) with a payload of about 280kg. This was about a year ago and things have progressed quite a lot since then (both in terms of SS kites and my particular boat development - the latter is now foiling). Also I wouldn't discount their strength - I don't think "...
they are very fragile due to the light materials they are built with..." is necessarily accurate. 12m is about half the normal sail area of a Nacra 5.8 and we had quite a bit more payload than the normal crew of 2. We were doing about wind speed when reaching in 15knots and upwind wasn't too shabby.