Which Leonardo da Vinci design used two separate hulls to improve a boat’s stability?

Leonardo da Vinci’s double-hull ship design used two separate hulls to improve a boat’s stability.

Leonardo explored a double-hull arrangement in his studies of boats and naval engineering. Two parallel hulls can provide a wider base than one narrow hull, reducing the tendency to roll. The same broad principle later appeared in catamarans and other multihull vessels, although Leonardo’s drawing was a design study rather than a modern production blueprint.

His interest in the arrangement fits his wider investigation of water, buoyancy, resistance, and ship construction. Leonardo filled notebooks with observations about how vessels move and how their shapes interact with water. He also considered military and practical applications for boats.

A double hull is not identical to the internal double-bottom or double-side structure used in many modern ships for damage protection. Leonardo’s concept concerns two parallel floating hulls, a distinction that is often lost when his maritime inventions are summarized too broadly.