Leonardo da Vinci designed a double hull with two separate layers intended to help a ship remain afloat after damage.
A double-hull arrangement places an inner hull inside or behind an outer hull, creating a protected space between them. If the outside layer is breached, the inner layer may still prevent water from flooding the vessel’s main interior. Leonardo explored this principle in shipbuilding studies, showing his interest in improving maritime safety through structural design.
The idea should not be confused with a catamaran. A catamaran has two distinct hulls side by side, whereas a double hull is a layered arrangement around the same vessel. Nor does a double hull guarantee that a ship cannot sink; its effectiveness depends on construction, compartments, damage location, and loading.
Modern ships use double-hull construction for particular safety and environmental reasons, especially oil tankers. Leonardo’s Renaissance proposal was not a modern tanker design, but it anticipated a structural principle that remains important in naval architecture.