 In many cases, composite hulls are built by sandwiching thin fiber-reinforced skins over a lightweight but reasonably rigid core of foam, balsa wood, impregnated paper honeycomb or other material.Perhaps the earliest proper hulls were built by the Ancient Egyptians, who by 3000 BC knew how to assemble wooden planks into a hull.Hulls come in many varieties and can have composite shape, (e.g., a fine entry forward and inverted bell shape aft), but are grouped primarily as follows