Her long association with the U.S. Navy began soon after her return from Peru. She was commissioned a Lieutenant Junior Grade in the WAVES, a women's unit of the Navy, in 1943 and called to Washington, D.C., where she organized and headed the new Oceanographic Unit of the Navy Hydrographic Office, working with Roger Revelle and others until June 1946. By 1944, the Joint Chiefs of Staff expanded Sear's responsibility to include management of over 400 personnel, 100 more than typical for a naval destroyer. Her unit was charged with aiding the Navy in strategic maneuvers through providing analysis of tides, surf heights, and other oceanic metrics to give the Navy a strategic advantage.