Leonardo da Vinci sketched a double hull using two layers of ship construction as a safety feature.
A double hull places an inner hull inside an outer hull, creating a protected space between them. Leonardo’s notes include a proposal for this arrangement, which could reduce the risk that damage to the outside of a vessel would immediately flood its interior.
The concept belongs to Leonardo’s broader studies of water, ships, canals, and hydraulic engineering. He did not invent every later form of double-hull vessel, and his sketch was not a modern tanker design. Its importance is that it shows an early understanding of separating a ship’s watertight interior from its exposed outer skin.
Double hulls later became especially important for oil tankers. International rules adopted after major tanker spills required double hulls for many new tankers, because the extra barrier can reduce oil release after a collision or grounding.