Leonardo da Vinci proposed a double hull to improve a vessel’s safety.
Leonardo’s maritime studies included a ship with two layers of hull structure. The inner and outer shells were intended to provide additional protection if the outer surface was damaged. This concept resembles the basic safety principle of later double-hull ships, in which separated hull layers can reduce the chance that a collision or grounding immediately floods the main interior.
Leonardo did not invent the modern oil tanker or establish contemporary naval standards. His drawing belongs to a broad collection of Renaissance ideas about ships, canals, pumps, bridges, and water management. Some of his marine proposals were practical, while others were experimental or remained on paper.
The term “double hull” can also describe modern ship construction with separate inner and outer bottoms or sides. Leonardo’s concept should therefore be understood as an early protective-hull idea, not a complete modern engineering specification.