What ship feature did Leonardo da Vinci study to reduce flooding after hull damage?

Leonardo da Vinci studied a double hull as a ship feature intended to reduce flooding after damage.

His naval and hydraulic notes include ideas for strengthening ships and dividing vulnerable spaces. A double hull places an additional layer or compartmented structure inside or around the outer hull. If the exterior is breached, the inner layer can help keep water away from the main interior and preserve buoyancy.

Modern ships use double-hull construction for safety and environmental protection, especially in tankers, but Leonardo’s Renaissance proposal was not a modern naval standard. His notes contain many exploratory concepts, and historians must distinguish between a clearly engineered proposal and a device that was built and tested.

The idea is also different from watertight bulkheads. Bulkheads divide the interior into compartments, whereas a double hull adds a second hull layer or protective space. Both methods can limit flooding, and later shipbuilders combined such principles in more systematic designs.