Thanks. I've already bought some time ago a longboard leash for the purpose of using the Serenity like a SUP (already succesfully tried suping on it but low wind limit of Serenity is so low that SUPing need is rare, hehehe).
A pair of cheap fitness carpets and I have the solution (3,5 euro x2) both for the fragility of F158 deck and... of girlfriend.
And then the two twins centerboards, hehehe, I like experimenting (when not windsurfing!).
Really I've aready got a new Chiemsee emergency fin system (9 euro on ebay.de), that is hidden on a simple mast base protector, and supposed to work in case of loosing the fin, it has to be strapped to the stern of the board. I was thinking to try it with longer straps as a centreboerd for Formula (at very low speeds), but the twin V shaped fins are so tiny...
Imagination travel when body is not windsurfing