Aft view of the U.S. Navy destroyer escort USS <i>John Willis</i> (DE-1027), circa in the early 1960s. <i>John Willis</i> was the first U.S. Navy ship to receive an experimental variable depth sonar (VDS), visible on the stern, in November 1960.
U.S. Naval History and Heritage Command photo <a rel="nofollow" class="external text" href="https://www.history.navy.mil/content/history/nhhc/our-collections/photography/numerical-list-of-images/nhhc-series/nh-series/NH-52000/NH-52346.html">NH 52346</a>