Leonardo da Vinci’s defensive ship design used a double hull to reduce the danger of flooding.
A double hull places an inner hull inside or behind an outer hull, leaving a space between them. Leonardo proposed this arrangement as part of his naval and military engineering studies. If the outer layer were damaged, the inner layer could help keep water away from the vessel’s main interior.
The idea reflects Leonardo’s practical interest in protecting ships during conflict. His notebooks contain many proposals for naval machines, canal works, pumps, and methods of controlling water. The surviving drawings do not always provide enough detail to establish how every design would have been built or operated.
Modern double-hull ships use the same broad protective principle, especially tankers and other vessels carrying liquids. Modern construction, materials, regulations, and compartment systems are far more advanced, so Leonardo’s sketch should be regarded as an early concept rather than a direct blueprint for a contemporary ship.