Leonardo da Vinci proposed a double hull as a ship-safety design using two parallel hulls.
Leonardo’s naval studies included the idea of separating a vessel’s outer structure into two hulls. The arrangement could improve stability and provide protection if one side were damaged. It resembles the basic configuration later associated with catamarans and some modern ships with double-hull construction.
The design reflects Leonardo’s interest in reducing the danger of leaks and improving the behavior of vessels on water. He studied hull forms, rowing systems, locks, canals, and other hydraulic subjects throughout his notebooks.
Leonardo did not create the modern oil-tanker safety standard simply by drawing this concept. A modern double hull has engineered spaces, watertight boundaries, and structural rules developed over much later centuries. His sketch is best understood as an early naval-engineering proposal, not as a documented shipbuilding program that transformed Renaissance shipping.