Leonardo da Vinci designed a double hull to help a vessel survive leaks.
The concept placed an additional inner layer inside the outer hull, creating a protected space between the two skins. If the outside shell was damaged, the inner hull could reduce the amount of water entering the vessel.
Leonardo included double-hull ideas among his naval and hydraulic designs. The proposal belongs to the history of damage protection rather than propulsion: it was intended to improve survivability, not to make a ship faster.
Modern double-hull construction is strongly associated with tankers and other vessels that need protection against collision or grounding. Leonardo’s Renaissance design was an early example of applying layered construction to marine safety.