Scorpion was a Skipjack-Class submarine. The Skipjack class was the nuclear-powered attack submarine class previous to the Thresher/Permit class. As such, they were not quite as deep-diving, although they did have a very sleek hull, which allowed for a high submerged speed. Skipjack-class submarines held (classified) speed records while using somewhat noisy 5-bladed screws, but lost this high speed when the screws were eventually replaced with quieter 7-bladed screws.