Double hull
（重定向自Double hulled ship）
![Single hull, Double bottom, and Double hull ship cross sections. Green lines are watertight; black structure is not watertight](/Images/godic/202501/09/DoubleBottomDoubleHull1023.png")
A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some distance inboard, typically by a few feet, which forms a redundant barrier to seawater in case the outer hull is damaged and leaks.