Leonardo da Vinci sketched a double hull to help prevent a damaged ship from sinking.
A double hull places a second layer of structure inside the outer hull, leaving a space between them. Leonardo’s notes and drawings explored this arrangement as a way to improve a vessel’s resistance to leaks and collisions. The concept shows his interest in applying mechanical and architectural principles to ships as well as land machines.
The design should not be confused with a watertight bulkhead. A double hull is a layered outer structure, while bulkheads divide a ship’s interior into compartments. Modern tankers and many passenger vessels use double-hull construction for safety and environmental protection, but Leonardo’s Renaissance sketch was not a modern naval blueprint. It was one of several ship-related ideas attributed to his notebooks and was not known to have been built by him.