What type of ship did Leonardo da Vinci sketch with double hulls for greater protection?

Leonardo da Vinci sketched a double-hulled ship as a protective naval design.

Leonardo’s engineering notebooks contain proposals for military vessels, including a ship with two hulls separated by a central space. The arrangement was intended to improve resistance to damage: if one side were breached, the second hull could help keep the vessel afloat.

The concept belongs to Leonardo’s wider study of naval warfare, shipbuilding, and defensive technology. He also designed or described other maritime devices, including paddle-driven craft and ideas for attacking enemy ships underwater. These drawings show experimentation with naval problems rather than a single finished invention.

The double-hull idea should not be equated with every modern twin-hull vessel. A catamaran has two parallel hulls primarily for stability and speed, while Leonardo’s proposal was presented in a military context, with protection from attack as a central purpose. No contemporary evidence shows that Leonardo’s double-hulled warship was built.