Yes, cuben .69 stuff, got the air valve in alright, all C3, still chasing small leaks on the ends, got to figure a surefire way there. Definitely thinking about internal sponsons for my kayak, next winter rebuild. Heavier cuben would work better. Ya, packraft, scary but light, would be way cool, worry about puncture resistance, need efficient construction methods or speed weeks chasing leaks.
Also, uberlight rowing cat?!