I used mainly 4mm marine plywood except 6mm for the stringer and 18mm corner (cedar) for the connection between the deck and the rails (this corner was a pain to bend).
I made pockets for the fins with plywood and glued the fin box with epoxy and 2x 4oz fiberglass cloth.
The pocket for the strap insert are made of polystyrene and filled with epoxy and microballons.
I rode the board on Saturday for the first time (nearly lost it and my kite after 15 minutes, what a nightmare!).
It???s very pleasant to ride, quite fast, stable and comfortable. It puts a little bit more pressure on the front leg which will unload my back leg crossing the channel.
It did few 5km tacks where I managed to average around 22knots (this makes the L2L in 26 to 27 minutes which would be better than the 29 minutes I did last year).
I???ll do more test after the race to try different fin position and fin length. At the moment I have 19cm fin at the back and 15cm at the front.
And yes I spent more time on my board than my lawn these last weeks.