Leonardo da Vinci sketched a double hull as a ship-safety feature using two separate hull layers.
A double-hull arrangement places an inner hull inside an outer hull, leaving a protective space between them. If the outer surface is damaged, the inner hull may help keep water from reaching the cargo or ship’s interior. Leonardo explored this idea in his studies of naval engineering and ship design.
The concept should not be mistaken for a modern claim that Leonardo invented the entire shipping industry’s double-hull system. Double hulls became especially important in later shipbuilding, including oil tankers, where they help reduce pollution after collisions or groundings.
Leonardo’s proposal illustrates his interest in preventing failure rather than merely responding to it. His notebooks contain many designs for canals, locks, bridges, boats, and water-lifting devices, but not all were built or tested in his lifetime.