I have a true story on the concrete thingy!!!

Booth made an F18HT of an A-cat (M18) and had to add loads of weight on the boat to get it up from 75kg to 130kg of boat weight. He didn't use concrete, he used lead in the main beam. Some of the weight came from a taller mast, bigger centerboards, bigger sail and spi kit but the rest was lead.

/håkan