Leonardo da Vinci proposed a double hull as a ship feature intended to reduce the danger of damage to the vessel’s outer skin.
A double-hull arrangement places an additional layer inside the outer hull, creating a space between the two structures. If the outside layer is pierced, the inner layer can help keep water from immediately reaching the ship’s main interior spaces.
Leonardo included the concept among his studies of ships and naval engineering. His notebooks contain many proposals for improving vessels, including methods related to construction, propulsion, and movement through water.
The idea should not be confused with a modern double-hulled ship built to meet detailed safety regulations. Contemporary double hulls use engineered compartments and structural standards, while Leonardo’s proposal was an early conceptual form rather than a complete modern specification.