Just as info.

My F12 hull has a total surface area of 5 sq. mtr. and when it is made out of 4 mm ply it will weight 17.5 kg per hull. From 5 mm thick Polyethylene it will weight at least 25 kg per hull, but probably more because of the stiffeners. Polyethylene is surprisingly flexible. They aren't calling the Dart 16's tupperware boats for nothing. The sides of the earlier versions do indeed feel alot like tupperware. Feeling the hull wobble underneath you will sailing is not a reinsureing experience.

Wouter