Leonardo da Vinci proposed a double hull to help a ship survive damage from a breached hull.
A double-hull arrangement places an inner hull inside an outer hull, creating a space between them. If the outer skin is damaged, the inner barrier can reduce the chance that water will immediately reach the ship's vital interior. Leonardo explored this idea in his studies of ships and naval engineering.
The concept is associated with Leonardo's broader interest in improving safety and control on water. His notebooks contain many ideas for boats, canals, locks, and mechanisms for moving water. A double hull is a structural feature, not a complete ship design or a propulsion system.
Modern ships use double hulls for several purposes, including protection and containment. In oil tankers, international rules made double hulls an important safety requirement after major pollution disasters. Leonardo's proposal was centuries earlier, but the basic protective principle is recognizable.