What type of armor did Leonardo da Vinci propose for a warship’s hull?

Leonardo da Vinci proposed a double hull for a warship’s hull.

The concept placed an additional layer or inner structure inside the outer hull, creating a protective separation between the ship’s interior and external damage. Leonardo considered such arrangements in his naval and military engineering studies, where collisions, impact, and leaks were serious risks.

A double hull can improve survivability because damage to the outside does not necessarily open the protected internal space directly. Modern tankers and some other ships use double-hull construction for related safety reasons, although their materials, regulations, and engineering differ greatly from Leonardo’s sketches.

The design is sometimes described loosely as armor, but it was not a modern steel armored warship. Leonardo’s proposal was an early structural protection concept, part of a wider group of ideas for defensive ships and naval machinery.