Come now, the Titan should never have been built, the primary cause of loss was the carbon fiber laminate which is simply the wrong material for a submersible. This is not hindsight, there's a five year old terse answer on Quora of all places stating this: https://www.quora.com/Is-it-feasible-to-build-submarine-hull... and again three years ago https://www.quora.com/Why-isnt-the-military-navy-using-carbo...

> Carbon fiber’s compression strength is poor. Its shear strength is low. It doesn’t dent; it either splinters or returns to shape and hides severe damage in the laminate.