A ledge is a secondary, athwartships framing member in a wooden ship's deck structure. It runs parallel to the heavy main beams but is lighter in scantling, bridging the gap between the longitudinal carlings. Ledges provide the necessary intermediate support for the deck planks, preventing them from sagging under the weight of cargo, artillery, or crew foot traffic.
Heard on the job
We need to replace three rotten ledges before we can lay the new deck planks on the port side.