US Navy Waterline Reference Plate

This is a U.S. Navy waterline reference plate, marking the 39-foot waterline level inside the ship. It specifically marks the waterline (W.L.) at a certain height. 3" x 3"

• "39 FT." → This indicates 39 feet above the keel (baseline).

• "W.L." → Abbreviation for Water Line.

Purpose:

These brass plates were mounted on bulkheads or structural frames inside naval ships to provide quick reference to shipbuilders, inspectors, and crew about the vertical location relative to the ship’s design waterline.

• They helped engineers, maintenance crews, and damage control teams know exactly how high above (or below) the waterline a compartment or passage was located.

• Essential in damage control: if a compartment was reported flooded, officers needed to know how close that was to the ship’s waterline.