A low drag ship hull generally includes a side air cavity initiated by wetted bow section, bottom air cavity initiated by wetted bottom nosepiece, wetted stem section that closes a lower portion of the side cavity, wetted bottom tailpiece that closes the bottom cavity, stabilizing fin, and propulsor. The bottom of a catamaran hull cross structure includes bow impact alleviator. Optional flaps in the stabilizing fins, together with optional all-movable canard fins are used for control. Different wetted bow sections and retractable plates are used for starting side cavities. A low drag hull may utilize multiple air cavities. A new low drag hull includes a new upper bottom air cavity that is initiated by an upper bottom wetted nosepiece, and closed by an upper bottom tailpiece. Alternative designs include a shortened forward hull spaced ahead of a shortened aft hull, and a hydrofoil-supported trimaran with low drag hulls.