Colin,



This is because the A is built as a foam sandwich with carbon on each side of foam. The dar is just a layer of glass/epoxy/gelcoat to keep the water out.

Give the side of a Dart a firm tap and it either moves and pops back, or breaks

Give the side of a foam sandwich boat a firm tap (not suggesting you do) and you get a "dimple" as the foam compresses and then does not return to it's old shape.

You can fill the bash you have with any filler, but make sure the area is very clean first and rough it up slightly so it sticks properly.