USS Thresher

On this day in 1963 the nuclear submarine USS Thresher sank with all hands. It was the first post WW II peacetime submarine casualty. The mystery of her loss, and the efforts to find her location and determine the cause, resulted in the realization that a new engineering discipline, Ocean Engineering, was needed to cope with the problems of designing for ocean forces. It also led to the development of deep ocean search and rescue capability.

The loss of the Thresher is particularly poignant to me. I was born and raised in New Hampshire. Dad worked at the Portsmouth Naval Shipyard. Fathers of my friends worked there. I attended her launch with my Cub Scout Den. I still have mementos from the launching ceremony. What most people don’t realize is that 17 civilians also went down with her. They were shipyard employees and field engineers who were there to observe the operation of the subs systems. My father, or fathers of my friends, could have been onboard just as easily.

It turned out she was a victim of the Joule-Thompson Effect. Stated simply, the J-T Effect says that when the pressure on a compressible fluid under high pressure is reduced, the fluid will cool. Its simple high school physics. Mr Wizard TV show stuff. It was surmised that the Thresher suffered a piping leak that caused her reactors to shut down, or SCRAM. When they tried to blow the ballast tanks with high pressure air, the moisture in the compressed air froze because of the J-T Effect. The ice blocked the piping and shut off the ballast blow.

Take a minute if you will and go here and read the obituaries of the men lost on the Thresher. The crew included a few WW II veterans, several African Americans and two brothers. These men were the cold warriors of that era.