The theoretical investigation was based on an analytical method because previous work proved that, in general, it was superior to numerical methods for this particular problem. It was hoped that the details from the current series of models, together with the new design chart, would enable some smaller submarines to descend to the bottom of the Mariana’s Trench (11.52 km or 7.16 mi); one of the models collapsed at a pressure of about 1000 bar, which was equivalent to a submarine diving to a depth of about 10 km (6.2 mi).