Noun
The upper edge of a vessel's or boat's side; the uppermost wale of a ship (not including the bulwarks); or that piece of timber which reaches on either side from the quarter-deck to the forecastle, being the uppermost bend, which finishes the upper works of the hull.
Source: Webster's dictionaryAt the gunwale or top edges of the planking there are longitudinals, and sometimes a little below the gunwale there are additional longitudinals to support the rowing seats or thwarts. Source: Internet
Bracing lines were attached to the luff and led through holes on the forward gunwale. Source: Internet
The oars did not use rowlocks or thole pins but square holes cut below the gunwale line. Source: Internet