Leonardo da Vinci proposed a double hull to make a vessel safer if its outer hull was damaged.
His naval drawings include ships with two layers of hull structure, creating a space between the outer and inner surfaces. This arrangement could help keep water away from the vessel’s interior after an external impact or breach.
The principle resembles the later double-hull construction used in some ships, especially tankers. A second barrier can reduce the chance that a collision or grounding immediately opens the cargo or machinery spaces to the sea. Leonardo’s proposal therefore connected structural design with damage control.
Leonardo did not invent every later form of watertight compartmentation, and his drawings were not modern naval plans. The term “double hull” is the precise answer because it describes the paired outer and inner shell, whereas a bulkhead is an internal wall dividing a ship into compartments.