Leonardo da Vinci proposed a double hull to make vessels safer from leaks.
A double-hulled vessel has an inner hull separated from an outer hull. If the outside layer is damaged, the inner layer can continue to hold water out of the ship’s interior. Leonardo’s sketches show that he understood this principle as a way to improve maritime safety.
The proposal reflects Leonardo’s practical study of boats, water flow, and naval engineering. His notebooks contain many designs for vessels and hydraulic machines, although not every design was built or tested.
Modern double-hull construction became especially important for oil tankers and some other ships. Leonardo’s Renaissance proposal should not be mistaken for the complete modern engineering standard: contemporary ships use carefully calculated compartments, structural materials, and safety systems that were unavailable to him.