Leonardo da Vinci designed a double hull using two layers to improve a ship’s protection from leaks.
His maritime studies included a boat with an inner and outer hull separated by a space. The arrangement was intended to make the vessel more resistant to damage and flooding. Leonardo also explored pumps, locks, canals, and other hydraulic engineering problems, so the design fits within a broad program of studying water transport.
A double hull is not the same as a submarine hull. It is a structural arrangement in which a second layer surrounds or lies beneath the primary hull. Modern tankers use double hulls to reduce the chance that a collision or grounding will rupture their cargo tanks and release oil.
Leonardo’s proposal was not a modern tanker design and was not built as a standardized ship type in his era. Its importance lies in recognizing the protective value of separating the vessel’s main interior from the outer shell.