In Portsmouth, New Hampshire family members and friends on Wednesday, April 10, gathered at a pier tossing wreaths into the churning waves in an emotional service in remembrance of the 129 Navy crew members who lost their lives in the deadliest submarine disaster in U.S. history.
Fifty years ago, on April 9, 1963 USS Thresher, a nuclear powered attack submarine commanded by Lieutenant Commander John Wesley Harvey, left Portsmouth at 8 a.m. and met up with submarine recue ship Skylark at 11 a.m. to begin dive trials the following day in the North Atlantic some 190 miles east of Cape Cod, Massachusetts. On the morning of April 10, at 7:41 a.m., Thresher begins its descent to the 1,000 feet test level. At 7:52 a.m. Thresher levels off at 400 feet and inspects the boat for leaks. It reports to Skylark that none were found. At 8:09 a.m. Commander Harvey reports reaching half the test depth.
At 8:25 a.m. Thresher reaches 1,000 feet. At 9:02 a.m.Thresher is cruising at just a few knots (subs must cruise slowly and cautiously at great depths since a sudden jam of the diving planes can send the boat below test depth in a matter of seconds) and reports to Skylark that she is turning to course. At this point, the transmission quality from Thresher begins to noticeably deteriorate.
At 9:09 a.m. it is believed that a brazed pipe joint ruptured in the engine room. The crew would have attempted to stop the leak as at the same time the engine room would be filing with a cloud of mist. In only a few seconds the moisture freezes the pressurized air in the rapidly expanding pipes halting the effort to blow ballast.
At 9:12 a.m. Skylark attempts to contact Thresher. There is no immediate response. At 9:13 a.m. a garbled transmission from Commander Harvey has a few recognizable words “Experiencing minor difficulty… attempting to blow…”
The submarine, growing heavy from water flooding the engine room, continues its descent. Another attempt to empty the ballast tank fails due to the formation of ice. At this point, Skylark can hear the hiss of compressed air over the loudspeaker. At 9:17 a.m. a second transmission is received from Thresher with a partially recognizable phrase “Exceeding test depth.” Skylark continues contacting Thresher repeatedly calling for a radio check, a smoke bomb or some other indicator of the boat’s condition.
Sinking at 130 feet per minute, Thresher’s hull collapsed at 9:18.24 at an estimated depth of about 2,400 feet, more than 400 feet below the designated collapse depth. The disaster timeline: 1 hour and 31 minutes.
What followed was the inevitable heartbreak of notifying 129 families that their loved ones were lost at sea, starting with Commander Harvey’s wife.