Leonardo da Vinci proposed a double hull to improve survival after a ship’s hull was breached.
A double hull places a second layer of structure inside the outer hull, creating a space between them. Leonardo’s maritime sketches included the idea as a protective measure: if the outer shell were damaged, the inner shell could help keep water away from the vessel’s interior.
The concept belongs to Leonardo’s wider studies of ships, naval warfare, water resistance, and transport. It was a design proposal rather than a documented shipbuilding program that he completed and tested.
Modern ships use double-hull construction for several purposes, including impact protection and pollution prevention. The modern applications should not be read as proof that Leonardo’s exact Renaissance design was identical to today’s engineering standards.