Leonardo da Vinci proposed a double hull as a protective feature for ships.
A double hull places two layers of hull structure around some or all of a vessel’s sides and bottom. The space between them can provide protection against punctures, collisions, and water entering the ship’s interior.
Leonardo included ship-related engineering ideas in his notebooks, reflecting his work on military and civil projects. His double-hull concept belongs to a long history of attempts to make vessels safer and more resistant to damage.
The idea should not be confused with modern tanker regulations. Double hulls became especially important in modern oil transport because the outer layer can help protect cargo tanks after a collision or grounding. Leonardo’s proposal was an early conceptual design, not a modern standardized shipbuilding system.