Sub Sunk- Plus 55 Years

55 years ago today, the USS Thresher (SSN-593) was lost. She was the lead ship of her class, which was renamed the Permit class.

The loss of the Thresher uncovered a number of problems with quality control and submarine construction methods. They weren't so much of an issue during the war, but the then-new nuclear submarines could dive about a thousand feet deeper than the American submarines built during the war.

The procedures for constructing and QCing submarines was radically changed with the development and implementation of the SUBSAFE program. No SUBSAFE-certified submarine has been lost, as of today. (USS Scorpion was built before the loss of the Thresher )