the older boats had air pockets for floatation. the foam was not required. the hole in bow deck might be for sail rigging mast. have a friend with that option in his older southbay .if you look under deck down on floor there is a female receiving block for mast if chris still has his hawk pull mold off his flaps they can be made from glass. to shape grass rails put wood in water till wood is real wet then clamp them to outer rub rail to get shape leave wood to get dry,this lets you work contour without splits.