Leonardo da Vinci proposed a double hull to reduce the risk of a ship sinking after hull damage.
A double hull places a second layer of structure inside or around the main outer hull, creating a protected space between the two surfaces. If the outside is breached, the inner hull can help keep water away from the vessel’s main compartments. Leonardo’s notebooks include shipbuilding ideas associated with improving safety and resistance to damage.
The concept is an example of how Leonardo applied mechanical reasoning to naval design. It does not mean that he invented every form of double-hulled vessel, since boats with multiple hulls and protective structures have appeared in different cultures and periods. His proposal is notable for recognizing the value of a redundant barrier.
Modern ships use double hulls in specific contexts, including many tankers, where the arrangement helps protect cargo tanks from collision or grounding. Modern marine engineering, however, adds complex structural, stability, and safety requirements that go far beyond Leonardo’s Renaissance sketches.