Leonardo da Vinci proposed a double hull to make ships safer if their outer hull was damaged.
A double hull places a second watertight layer inside the outer hull, creating a protective space between them. Leonardo included this idea among his studies of ships and naval engineering. The arrangement could reduce the chance that a puncture in the outside skin would immediately allow water into the main interior of the vessel.
The concept reflects Leonardo’s habit of adapting structural principles from one field to another. By separating the outer surface from the protected interior, the design aimed to improve buoyancy and survivability. It was a proposal rather than a demonstrated shipbuilding innovation, and surviving drawings do not establish that Leonardo constructed a full-scale vessel using it.
Modern double-hull construction is especially associated with tankers, where the space between hulls helps protect cargo tanks from collisions and groundings. Leonardo’s proposal should not be described as the first modern tanker hull. Its importance is that it shows an early, clearly recognizable use of layered ship protection.