Leonardo da Vinci designed a double hull as a protective ship structure against flooding.
His naval studies included vessels with two layers of hull material separated by a gap. The outer layer could take damage while the inner layer helped preserve the watertight body of the ship. This is the same broad protective principle later associated with double-hulled ships and modern tankers.
Leonardo’s proposal was part of a wider collection of maritime ideas, including boats, pumps, and methods for controlling water. It should not be interpreted as a complete modern ship design or as proof that he built a working double-hulled vessel. His notebooks often record concepts and mechanisms rather than finished engineering projects.
Modern double hulls are used for structural and safety reasons, especially in oil tankers, where an outer shell can provide separation from the cargo tanks. Leonardo’s concept is historically notable because it anticipated the value of layered protection in marine construction centuries before modern shipbuilding materials and regulations.