·noun ·pl Raised pieces of wood of iron around a hatchway, skylight, or other opening in the deck, to prevent water from running bellow; ·esp. the fore-and-aft pieces of a hatchway frame as distinguished from the transverse head ledges.
See coamings of the hatches ...
The Sailor's Word-Book
Certain raised work rather higher than the decks, about the edges of the hatch-openings of a ship, t...