Leonardo da Vinci proposed a double hull to make ships safer against damage and leaks.
Leonardo’s naval studies included the idea of building a ship with an inner and outer hull. The separation was intended to help protect the vessel if the outside shell was breached. This reflects his interest in buoyancy, water pressure, shipbuilding, and the practical problems faced by vessels at sea.
A double hull is not simply a thicker hull. It creates a space between two hull layers, providing additional protection and, in modern vessels, room for ballast, fuel, or other systems. Leonardo’s proposal was an early conceptual example of a safety principle that later became important in ship design.
The idea should not be confused with a twin-hull catamaran. A catamaran has two distinct buoyant hulls side by side, while a double-hulled ship has one main vessel protected by an additional outer layer. Leonardo’s design was a proposal and did not become a standard Renaissance shipbuilding practice.