Leonardo da Vinci included a double hull in a ship design to reduce flooding after damage.
A double hull places an inner hull inside an outer hull, leaving a space between them. If the outer shell is breached, the inner hull can remain watertight and keep water away from the main interior. Leonardo explored this principle in ship designs during the Renaissance, well before it became an established feature of some modern vessels.
The idea reflects Leonardo’s interest in naval engineering and damage control. Ships used in war or transport could be threatened by collisions, weapons, or rough water, so adding a second protective layer offered a possible safety advantage. The concept would also require careful construction because extra weight and complexity could affect stability and speed.
Leonardo’s proposal should not be confused with the modern legal requirement for double hulls on certain classes of oil tankers. Those rules were introduced centuries later for environmental protection after major tanker accidents. Leonardo’s design was an early engineering concept, not the source of every later double-hull application.