stringers are structural members that run the direction of the hull on the inside sides. In the 80's, most Nacra hulls had a horizontal fiberglass stringer that went the length of the hull on the inside. It was literally a piece of cardboard tubing overwhich several layers of fiberglass were laid. This gave the sides of the hulls additional stiffness. Somewhere around 1983, Nacra started using foam core construction instead of solid fiberglass. The foam core boats may not have this stringer and are constructed just like it sounds - two layers of fiberglass sandwiching a foam core (most boats today are built this way).

Bulkheads are vertical plates inside the hull that should be attached almost all the way around. They are usually open on the bottom to allow trapped water to escape sections of the hulls. The bulkheads should be located at about the rear beam and the front beam.

The boat will have to have forward inspection ports for you to see most of these structural items.

If the boat is solid fiberglass and is getting soft, repair will be difficult.