coaming

thumb|Hatch coaming (bottom right) on a bugeye Coaming is any vertical surface on a ship designed to deflect or prevent entry of water. It usually consists of a raised section of deck plating around an opening, such as a cargo hatch. Coamings also provide a frame onto which to fit a hatch cover.

The protective metal sheeting or plating protecting against water entry into ventilation shafts in large ships is called a coaming as it fulfills the same water-deflection purpose.