Bulkhead - Kakuheki (English spelling)

Generally, it means a partition wall, but in marine terms, it means a partition wall that divides the inside of a ship into several compartments. Learning from lessons such as the sinking of the Titanic (1912), major bulkheads are now built with the clear purpose of confining flooding to one compartment. In addition, they also serve other purposes such as strengthening the hull structure, preventing the spread of fire as a fire barrier, and forming cargo holds and water and oil tanks. Some bulkheads are built simply as partitions, and usually one bulkhead serves multiple purposes. Bulkheads that are nailed horizontally to the hull like bamboo joints are called transverse bulkheads, and the number of them is determined according to the length of the ship. Bulkheads that are built in one or two rows along the length of the ship are called longitudinal bulkheads. Bulkheads are made of flat steel plates with stiffeners (shaped steel framework) for reinforcement, and the flat plates are thicker at the bottom to withstand water pressure when flooded. There are also corrugated bulkheads that omit stiffeners by bending the plates into a corrugated shape to maintain strength.

[Morita Tomoharu]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

一般的には間仕切りの壁をいうが、船舶用語では船体の内部をいくつかの区画に分ける仕切り壁をいう。タイタニック号沈没（1912）などの教訓から、主要な隔壁は浸水を一つの区画に局限するという明確な目的の下に設けられるようになった。そのほか船体構造の強化、防火壁としての延焼防止、貨物倉や水・油タンクの形成といった役割ももっている。また単なる仕切りのために設けられるものもあり、通常一つの隔壁でいくつもの役割を兼ねている。竹の節(ふし)のように船体を横方向にくぎっているものを横隔壁といい、船の長さに応じてその数が定められている。また、船の長さ方向に沿って1、2条設けられるものを縦隔壁という。隔壁は鋼製の平板に補強のためのスチフナstiffener（形鋼の骨材）をつけた構造で、平板は浸水時の水圧に耐えるために下のほうほど厚くする。板を波形に曲げて強度を保ち、スチフナを省略した波形隔壁もある。

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