Leonardo da Vinci’s ship-safety concept used a double hull to make vessels more resistant to flooding.
Leonardo’s maritime studies included a vessel with two layers of hull structure. The space between the layers could provide protection if the outer shell was damaged, an idea related to later double-hull construction. The concept appears among his broader studies of ships, canals, pumps, and hydraulic engineering.
A double hull is not the same as a catamaran. A catamaran has two separate parallel hulls that support the vessel, while a double hull places one protective hull inside or alongside another. Modern tankers and some other ships use double-hull construction for safety and environmental protection.
Leonardo did not create the modern maritime standard. His drawing is significant because it records an early attempt to reduce the consequences of hull damage through layered construction.