Okay, thank you all for the interest. My goal was to find out if there were other serious home-builders with seaproof cats. May there aren't or atleast rare.
My home-building all has to do with my way of catsailing; I could not buy what I'm looking for: light, stiff and strong, single-handed, and easy to beach and fit for high seas.
Maybe we meet again in future with videos or photo's.