Leonardo da Vinci proposed a double hull as a shipbuilding safety feature with two separate hull layers.
His naval designs included an inner and outer hull separated by a space. The concept was intended to reduce the danger of flooding if the outer skin were damaged. A second layer could provide additional protection for the vessel’s contents and help preserve buoyancy after a collision or breach.
Leonardo’s proposal belongs to his broader work on ships, canals, pumps, and military engineering. It was a design concept, not the source of the modern international requirement for double hulls on every relevant vessel. Modern double-hull construction uses engineered compartments, structural members, and regulated dimensions that differ from a Renaissance sketch.
The idea is sometimes confused with watertight bulkheads. Bulkheads divide a ship internally, while a double hull creates a second shell around the vessel. Both features can limit flooding, but they are not the same construction method.