The Plans I am developing requie a Ballasted Center board or Dagger Board. I am after information / leads to information showing how others have gone about their structural design to withstand the side loadings a ballasted board creates. 500-700 kg. I plan to have a further 500-700 in the keel for an all up 1200kg of ballast. The hull is a Presto /Sharpie type intended for extensive coastal use so the case must be up to some rough weather/water usage.
As for the Centre board vs Dagger board I believe this issue has been done to death several times over and for me it is a personal decision based mainly on the two following issues. Dagger board = lower CoG and more efficent. Center board = more forgiving if the bottom is hit (Assumeing it is not pinned down)