Gato, the mast design I am still thinking of. Don't worry I will be using no wood at all (besides for strengthening the places for screwes and so on). I'm still searching for a method for increasing the fiberpercentage with regard to resin without vacuum. My handlayup gives me now 50-50 % fiber-resin, which is to less for a mast.

With regard to the multi-layered skin again, I would like to add that in my opinion it is a serious alternative to the modern sandwhich-like skins which industry tends to use moreover. The danger of sandwhiches is always delamination and a weak outside for point-oriented loads.
The weak point in my skin construction is micro-cracking of the resin between the fibers. Which ofcourse can lead eventually to total breaking off (My shoulder-problems are a good example of that by the way).
In fact that's what I see when a surfboards breaks at the beach.
The stress loads on catamaran hulls are maybe a little less compared to that with regard to actual bending?