At in length, with a beam of and a waterline depth of , the six boats were the largest conventionally powered submarines in the world at the time of their commissioning. The submarines are single-hulled, and have two continuous decks. Each boat displaces when surfaced, and when submerged. The depth that the submarines can dive to is classified: most sources claim that the diving depth is in excess of , although some give the maximum depth as over . Following the near-loss of "Dechaineux" in 2003 when a seawater hose burst during a deep dive, the diving depth was reduced.