Upholder Class Boats Go To Canada
The Royal Navy's all nuclear-powered submarine force arrived just a few years after it accepted for service four modern diesel-electric submarines of the Upholder Class (designated SSK for hunter killer). The decision to retire these excellent boats was made for financial reasons following the Cold War. This note reviews the Upholders and their retirement from the fleet.
In the early 1970's, the Royal Navy planned a submarine force of 18 nuclear powered attack submarines (SSNs) and 4 ballistic missile submarines (SSBNs), with no SSKs. The SSN construction rate, however, could not keep pace; thus the Royal Navy decided in the late 1970's to build a new class of 10 modern SSKs, the Upholders. When they were proposed, the Royal Navy still operated several SSKs (Porpoise Class and Oberon Class) that had been built between 1955 and 1961.
The primary operation role of the Upholders was to deploy to Greenland-Iceland-UK (GIUK) gap with modern sensor suites and weapon systems as the final layer of the Cold War antisubmarine barrier against Soviet submarines entering the Atlantic from their Northern Fleet bases. Secondary tasks included those performed traditionally by SSKs in shore operations, special operations, support of surface ASW training, and - most important for the submarine flotilla - training of commanding officer and crews.
The Upholders design was subjected to much debate, and opinions differed widely. The final unit cost was estimated to be one third of an SSN's. In the event the expense of getting the first of class into service exceeded that cost considerably, although the quoted sale price was US$215 million each (at 1990 value).
The Upholders fire-control system was an updated version of that fitted to the Trafalgar Class SSN, and the sensor suite was drawn from various sources. The French passive-hull-sonar "Triton" was purchased and called 2040 in British service. The current 2046 towed array was installed, as well as micro-puffs passive ranging set, Australia's ping-intercept passive-ranging system was fitted to the second boat of the class as a trial.
A large double-armature motor on a single shaft provided propulsion through a large modern propeller. A 9,000-amphour battery capable of rapid charging along with two Paxman Velenta diesels (with twice the power of those in the Oberon Class) resulted in an extremely flexible propulsion system. Efficient hull design kept propulsion loads - and discharge rates — low, despite the increased operational electrical load. Patrolling at slow speeds would require 40 to 60 minutes of snorkeling per day; a transit at 8 knots would require snorkeling approximately 30% of the time. Top speed submerged matched that of any similar SSK and could be maintained for more than 90 minutes from a fully charged battery. Further, once a submarine reached the end voltage, it still had considerable capacity remaining for operationally useful speeds.
As with any new platform of radical design, numerous problems caused delay and increased costs. These difficulties were resolved by the time the class was retired from British service. To conserve manpower, a largely automatic system for controlling the sequencing of the valves for the weapon discharge was designed. It was successful in achieving near-silent discharge and a marked reduction of manpower, but, in certain circumstances, the hydraulic interlocks could allow the torpedo tube slide valve to open while the tube door was open. This could allow unrestricted flooding and loss of the boat. Weapon firings were possible through tortuous procedures and isolation of much of the system. This problem was corrected after redesign and re-engineering of the system.
The main motor was the largest of the type ever placed in service with the royal Navy, and miscalculations were made in the design of the software and hardware of the control system. During sea trials of the first of class, it was found that emergency reversals would generate peak back currents of more than 60,000 amps, causing spectacular fireworks and loss of propulsion thereafter. While this was detected early, it delayed the whole program for six months. From the second boat on, corrective measures were taken during construction.
Although powerful, the main engines were not especially sturdy. They were designed originally for use in railway locomotives, and stress of stopping the rotating parts from full power at the end of snorkeling led to many failures. Once reorganized, this was relatively easy to fix. Similarly, the motor generator sets were working at their maximum limits, and redesigned brushes and filters had to be fitted during the early operational life of the class. In addition, the exhaust temperature of the powerful generators was unexpectedly high and salt deposits in the exhaust-valve seating caused leaks when snorkeling was finished.
Other less dramatic problems caused a few headaches in the early years. Consequently, acceptance into service of the first of class was late by three years. Although subsequent boats had an easier time, the press found a great deal to harp on. As one of the early commanding officers I spent much time preaching the message that the boats were a great success. And what made them so?
The greatest strength of the class is its small acoustic signature. Benefiting from 35 years' money and effort expended to quieting nuclear powered submarines, they are extraordinarily quiet. On the main motor they were shown repeatedly to be all but detectable by passive sonar. But when snorkeling they had a signature comparable to a modern SSN. As a result of this success in silencing, the Upholders were exceptional platforms for passive sonar. They presented a difficult target to active sonar as well because they were small and fully acoustically tiled and much of their superstructure was made from composites. More over, because of the small size, adversaries could not easily exploit magnetic anomaly detection and other non-acoustic signatures.
Innovative technologies introduced in the control room included a local-area network supporting the majority of the sensors and fire-control system; remote viewing of periscopes via low-light television and infra-red cameras and unmanned helm and direct control of the propulsion motor from the control room. This in the small crew size of 7 officers and 40 men and the ability to fight the boat with a control room team of 8 crewmen, plus 4 in the sound room.
Outside the control room, the boats also featured a high degree of automation. New systems allowed remote sensing recording and control of machinery. Fire fighting in unmanned compartments could be initiated remotely and watch-keeping records could be taken automatically. This allowed the boats to be connected electronically in port, where one duty watch could monitor several hours safely. The small crews had little difficulty operating the submarines, and there was some room for further reductions in crew size as time passed.
Shortly after relinquishing command of HMS Unseen (S41), I had the good fortune to visit a Russian Kilo-class boat and made a direct comparison. The two classes had almost identical layouts. Talking to crew members, it was plain that the Russian boat had similar endurance and performance, but its noise isolation and shock resistance was suspect. Also, the larger crew 12 officers, 12 warrant officers and 33 conscripts — was crammed in with little regard for comfort or ability to rest while off watch. The most obvious shortcoming of the Russian boat was the crude control room equipment. It relied upon manual operation of all systems, using the remote controls as a backup. Interestingly, the Russian officers dismissed the Upholder Class as being too delicate and likely to fail because of over-reliance on automated systems. Having operated Unseen in all weather and in demanding circumstances, I can vouch for the effectiveness and sturdiness of these fine submarines.
As the future of the class looked rosy, the decision in 1993 to stop the program at four boats, followed closely by the decision to dispose of those already built, were bitter pills. The decisions were made for the most compelling of reasons: the need to save money. Offered the choice of affording four SSKs or one SSN the right choice was made at the time. Nonetheless, the boats were handy both surfaced and submerged, they were a joy to command. Widespread dismay broke out among young command-qualified officers, because commanding an Upholder as a lieutenant commander was a powerful stimulus to retention — and officers lucky enough to enjoy the experience became better nuclear captains.
At the time of the decision to withdraw the boats from the active fleet, a number of improvements to the class were proposed. The first four boats were built to a standard pattern, but the fifth of the class would have had several modifications, including increased bunk space, replacing rotating conversion machinery with static inverters and increasing fuel capacity by using spaces external to the pressure hull. There was also a project for future use of fuel cell to replace snorkeling cycles on patrol that would have been ready for an experimental installation in 1995.
After withdrawal from active fleet, the four boats sat at the Vickers yard for years until their fate was decided. They were offered to several navies, and Canada decided to accept them as replacements for its own flotilla of old Oberon Class SSKs. They will carry the names of Canadian towns and operate from the Pacific and Atlantic coasts (one of three boats respectively) of North America. They will be modified to enable them to carry Mk 48 torpedoes and new fire-control systems. Women will go to sea in these submarines, a modification considered infeasible in the Royal Navy because of the limited space. Once again, the US and Royal navies will have an opportunity to operate against them in training and tactical worthy opponents and superior training vehicles.