Leonardo da Vinci proposed a double hull as a ship-safety feature.
A double hull places two layers of the ship’s sides or bottom around an intervening space. Leonardo’s naval studies included the idea of separating the outer hull from an inner hull so that damage to the exterior would be less likely to flood the vessel immediately.
The principle anticipates a feature used in later shipbuilding, although Leonardo’s drawings were concepts rather than standardized construction plans. Modern double hulls are especially associated with tankers, where the additional layer helps reduce the chance that a collision or grounding will rupture cargo tanks directly.
A double hull is not the same as a watertight compartment system. Compartments divide the interior into sections, while a double hull creates a protective outer layer and space between hull surfaces. Leonardo’s broader studies of ships also examined paddles, pumps, and methods of improving naval maneuverability.