the.com/gunwale

means The upper edge of a boat's or ship's side, often where the hull's planking stops and the rail begins.

from A compound of 'gun' + 'wale' — 'wale' being an old word for the plank or ridge along a ship's side (related to the 'wale' in 'weal,' a raised ridge on skin). Originally it named the stout upper plank that carried the ship's guns, strengthened to take the recoil of cannon fire. The guns are long gone from most boats, but the name — and its stubbornly nautical pronunciation, 'gun-nel' — stuck.