The decision to increase the size of USS X-1’s hull was made in order to improve operational conditions, affording more space when it was operated by two individuals. Improvements were also made in order to allow the vessel to be operated by a single man, with duplicate controls and multiple periscopes installed. USS X-1 also featured a more rounded bow, while hydroplanes were also added in order to improve the vessel’s maneuverability. The vessel also included a diver lock-out chamber.