The nuclear missile submarine USS Growler (SSG-577) was commissioned on August 30, 1958, and began its sea trials that November. During dive trials, the submarine successfully reached the fleet submarine test depth of 475 feet (145 meters). As the submarine continued its dive, crew members recall hearing a pop followed by a rush of water from a hole in the overhead of the sonar room. The commanding officer ordered the crew to surface while crew members rushed to address the leak.
On the surface, the crew determined that shipyard workers had not properly sealed an unused cable opening. Rather than return to port, the crew was resourceful. They plugged the hole with two nickels and a rubber gasket. This repair allowed Growler to complete sea trials. Back in the shipyard, the nickels were removed and the hole properly filled. This plaque, with two nickels, commemorated the “Most Inexpensive Conversion in the History of the U.S. Navy.”