What kind of ship did Leonardo da Vinci design with a double hull for greater protection?

Leonardo da Vinci designed a double-hulled ship with two layers of hull construction. The arrangement was intended to make the vessel more resistant to damage and reduce the danger of flooding after a collision.

Leonardo’s naval studies examined hull shapes, buoyancy, propulsion, and defensive engineering. A second layer separated from the outer hull could act as a protective buffer, much as later double-hull ships used space between their shells for structural or safety purposes. His notebooks contain several ship and boat concepts rather than one completed vessel.

Leonardo’s proposal should not be confused with a catamaran, which has two separate parallel hulls that support a deck. A double-hulled ship has an inner and outer shell forming a protected structure. Modern tankers adopted double hulls primarily to reduce oil spills after accidents, centuries after Leonardo explored the concept for naval protection.