Leonardo da Vinci proposed a double hull as a ship feature intended to improve safety after hull damage.
The concept placed an inner hull inside an outer hull, creating a protective layer between the vessel’s interior and the surrounding water. If the outer shell were breached, the inner structure could help keep the ship afloat longer.
Leonardo’s notebooks contain many studies of ships, canals, pumps, and water movement. His double-hull idea belongs to this wider program of investigating how engineering could control water and reduce the effects of accidents.
The proposal should not be confused with the modern double-hull tanker, whose regulations and construction methods developed centuries later. Leonardo’s drawing was an early conceptual design rather than a documented full-size vessel built under his supervision.