Leonardo da Vinci’s two-hulled watercraft concept used a double hull.
Leonardo’s notebooks include naval designs with separated hulls and arrangements intended to improve stability and protect a vessel against damage. A double-hull arrangement creates two parallel hulls rather than one single central body. The concept is related to the broader catamaran principle, although Leonardo’s drawings should not automatically be treated as a fully developed modern catamaran design.
A major advantage of two hulls is stability: the distance between them can resist rolling. Separate hulls can also provide redundancy if one side is damaged, depending on the structure and buoyancy arrangement. Modern ships use double hulls especially for protection against oil spills and underwater collision damage.
Leonardo produced many maritime sketches, including boats, diving equipment, and water-powered machines. Most were exploratory designs rather than vessels known to have been built and operated.