Ukashi

…To keep a fishing net in the required shape underwater, it is usually necessary to balance the upward and downward forces of buoyancy and gravity. The buoyancy required for this is achieved by using ridges, also called uke or ukashi. It is first necessary that the ridges are large, but it is also desirable that the buoyancy does not change as much as possible over time when the net is underwater, such as by absorbing water or by being deformed by water pressure. …

*Some of the terminology explanations that mention "Ukashi" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…網漁具を水中で所要の形状に保たせるには，通常，浮力と重力という上下に働く力をうまくつり合わせる。このとき要する浮力を得るのに用いられるのがあばで，うけ，うかしなどともいう。あばの大きいことがまず必要だが，水中にあって時間がたつとともに吸水したり，また水圧で変形したりして浮力が変化することがなるべく少ないのがよい。…

※「うかし」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報