Thank you Roger for your quick answer. Here are some comments/questions to yours answer.
>>> You might remove about 5-7 lbs. (2.2-3.2 Kg.) but you probably won't improve the performance of the board as much as you think.
So the board will loose 2.2 -3.2 Kg weight eh? That sounds a lot !!! I was expecting less. The board is now 13 Kg and so it will go down to aprox. 10 Kg. (almost 25% down). I sounds like a big change to me and I can not understand why this change will not affect the performance of the board (providing of course that the rider is a good surfer). Of course I am not an expert so I trust you know something more here.
>>> Cut some closed cel foam to make filler piece
OK. That sounds easy. Thank you
>>> Then make up a new solid top plate from materials similar to the original deck plate.
But for this I do not have a clue. It sounds a bit complicated for someone who never used epoxy resin, polyester materials etc etc.
I guess there is no easier way. For example Starboard (or another third company) can not provide me with something like a cassette or something that can fit into the centerfin hole?
>>> purchasing a GO or Carve/Futura is a much better way
For sure ! I am going to buy a new board anyway (I was thinking Futura). The reason I made this post is because I don't want to sell the old one. I would like to keep it for days with less wind and bigger sails.
Thank you again
Greetings from Athens, Greece.