On this particular morning, a DD was getting ready for an ASW exercise off Mayport, FL. The two launchers were loaded with target practice charges (2x24). Exercise charges were the same as live Hedgehogs with the exception that the Torpex filler for the warhead was replaced by concrete. Just prior to departure for the exercise zone, the exercise was rescheduled to the next day; the 48 charges were left on their spigots overnight.
The next morning after quarters, a TM1 (first class torpedoman) went out to do voltage checks on the Mk 13 launcher. He plugged-in his meter, inserted the firing key in the panel, cocked the ripple switch, and tripped it. [Normally, at least one or more switches were open from underwater battery plot to the Mk 13 launcher and would have interrupted the firing voltage to the spigots — but not today. All five switches were closed and the spigots were fully armed and ready.]
The first indication anything was amiss was the first two charges left the spigots followed by the remaining 22 at 0.2 second intervals. The 24 projectiles soared into the air before plunging down into a base parking lot. The projectiles buried themselves about two feet into the ground. Three cars suffered “direct hits”; one in the trunk, one in the middle of the roof, and one in the middle of the hood. There were lots of ashen faces, followed by lots of excitement. One of the crew that watched from the bridge said: “This was the best pattern we [the ship] ever shot!”