The design included an updated version of the fire-control system being installed on the SSNs under construction at the same time, a state-of-the-art French passive sonar system, the then-current towed array, and a micro-puffs passive ranging set.
A large double-armature motor was powered by a 9000-amp-hour battery or a pair of Paxsman Velenta diesel engines. Slow patroling would require only 30 to 60 minutes of snorkling per day; an eight-knot transit would require snorkling some 30% of the time. Top speed matched any comparable SSK class and could be sustained for some 90 minutes.
However, the design did contain flaws. It was highly automated to reduce manning, and the weapon-discharge system that controlled the operations of the torpedo tubes could, under certain conditions, open the torpedo tube slide valve while the rear door was open. Had such an event actually occurred, unrestricted flooding would have resulted.
Miscalculations were made in the design of the main motor. During sea trials of the lead ship of the class, it was noticed that an emergency reversal ("crash back") would generate currents of more than 60,000 amps, which resulted in catastrophic and spectacular complete loss of propulsion.
The diesels were originally designed for use in railway locomotives, and were not intended to be rapidly stopped and started. Shutting them down after snorkling led to many failures. Similarly, the motor-generators were operated a full power for longer than expected, and consumed brushes and filters rapidly.
Acceptance of the class into service was delayed for three years while such problems were corrected. The result of those corrections, however, was an extremely capable design. When operating on battery, Upholders were almost undetectable on passive sonar, and when snorkling, their acoustic signature was comparable to their SSN contemporaries in normal operation. They were physically small, and thus difficult to detect by magnetic anomaly or other non-acoustic means.
A local area network was built into the Upholders, supporting most of the sensors and fire-control systems, including remote viewing through the periscopes using both low-light television and infrared, an unmanned helm, and direct control of the main motor from the conn. The boat could fight with a team of four in the sound room and a conn team of eight. Fire-suppression in unmanned compartments could be initiated remotely, and watch-keeping logs were automatically recorded. In port, the boats could be electronically linked such that one duty watchstander could monitor several submarines.
In 1993, HM Government decided to halt construction with only four boats launched, and furthermore to decommission the four in service. In 2002, Canada accepted the four Upholders as replacements for their old O-class submarines. One will operate in the Pacific fleet, three in the Atlantic.
Ships in Class
General Characteristics