Upholder/Victoria Class Submarine - Design

Design

The boats were designed and built by Vickers Shipbuilding and Engineering Ltd for the Royal Navy and are essentially identical to modern nuclear submarines (with the distinctive Albacore-derived teardrop hull and sonar-absorbing tiles) but run on diesel engines instead of nuclear reactors. These were Britain's first conventional submarines to feature the tear-drop shape, which greatly reduced the acoustic signature produced by the boat while cruising.

The boats were designed with advanced noise-attenuation features to reduce the radiated noise levels below those of the already very quiet Oberon class. There was also a reduction in the short time required to recharge the batteries to ensure a minimum exposure time of any part of the masts above the water. The design included an updated version of the fire-control system being installed on the SSNs under construction at the same time, designed to reduce stability problems at torpedo launch, a state-of-the-art French passive sonar system, the then-current towed array, and a passive ranging set.

A large double-armature motor is powered by a 9000-ampere-hour battery or a pair of Paxman Valenta diesel engines. Slow patrolling would require only 30 to 60 minutes of snorkeling per day; an eight knot (15 km/h) transit would require snorkeling some 30% of the time. Top speed matches any comparable SSK class - such as the Scorpène-class submarine - and could be sustained for some 90 minutes.

During construction of the first boats it was recognized that the weapon-discharge system design did contain flaws. The torpedo tube slide valve controlling operation of the torpedo tube doors could have, under certain system failure conditions, allowed the opening of the inner door while the outer door was open. The flaw was quickly fixed in the first three boats and the modifications included in the fourth boat while still under construction.

Miscalculations were made in the design of the main-motor control circuitry. During the sea trials of Upholder, when performing the specified trial for an emergency reversal ("crash back"), a flash-over incident occurred, which resulted in the complete loss of all power and propulsion. On investigation, this was traced to a fault in the design of the control circuitry insulation, resulting in a battery short circuit current of more than 60,000 amperes.

The diesels were originally designed for use in railway locomotives, and were not intended to be rapidly stopped and started. Shutting them down after snorkelling led to many failures. Similarly, the motor-generators were operated at full power for longer than expected, and consumed brushes and filters rapidly (the brush problems were not specific to the Upholders, and were a widespread issue on all UK RN vessels at that time).

Acceptance of the class into service was delayed for three years, partly due to the programme being scaled back by the MoD, while such problems were corrected. The result of those corrections, however, is an extremely capable design. When operating on battery power, Upholders are almost undetectable on passive sonar, and when snorkelling, their acoustic signature is comparable to their SSN contemporaries in normal operation. They are 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 can fight with a team of four in the sonar room and a conn team of eight. Fire-suppression in unmanned compartments can be initiated remotely, and watch-keeping logs are automatically recorded. In port, the boats can be electronically linked such that one duty watchstander can monitor several submarines.

The submarine has a single skin hull constructed of NQ1 high tensile steel. The outer side of the submarine's hull, casing and fin is fitted with about 22,000 elastomeric acoustic tiles to reduce the submarine's acoustic signature. The hull is 70.3 m in length by 7.6 m in width and with a depth of hull of 5.5 m. The fin or main sail houses a five-man lockout chamber. The submarine's escape and rescue system has been extensively upgraded with additional stowage space for escape stores and an underwater telephone to meet the Canadian Maritime Force requirements. The hull displacement is 2,168 t surfaced and 2,455 t dived. The submarine accommodates a crew of 48 including seven officers. There is room for an additional five mission crew, observers or training crew.