Walrus

The Walrus class is a relatively conventional SSK design, based on the two 2600 tons Zwaardvis class boats, featuring a full ocean-going operational capability. It is an improved class with similar dimensions and identical silhouettes except for the X-stern rudder system. In service since 1990, The Royal Netherlands Navy's Walrus submarine class is a replacement for the Potvis class. The Walrus can carry out anti-surface, anti-submarine, surveillance, special operations, and mine-laying missions.

Since 1988, these four submarines have been sailing all over their operational areas and beyond, proving that the Walrus class submarine is capable of operating all over the world. The operational range of the RNLN submarines lies mainly in the Eastern Atlantic Ocean, the North Sea and the Norwegian Sea, but also in the Mediterranean. Their missions are directed at anti-surface and anti-submarine warfare, carrying out surveillance, special operations, and the laying of mines.

The design of the boat was under the guidance of the Royal Netherlands Navy. Around 1950 the first class of locally-designed submarines emerged. Four triple-hull Dolfine class submarines were delivered to the RNLN in the period 1960-64. The triple-hull design achieved excellent diving depth with relatively thin steel plating. The development of the present Walrus class also stems from a different source, the Albacore, the US test submarine for high speed, forerunner of the nuclear attack submarines as well as their non-nuclear version of the 1960s, the Barbel.

As early as the 1960s, a conscious choice was made, by the Dutch Navy, for diesel-electric submarines rather than nuclear-powered vessels. The former can operate with lower noise levels and are thus eminently suitable for their tasks. A further advantage is that the construction and running costs of diesel-electric submarines are considerably lower than those of nuclear-propelled vessels.

The Royal Netherlands Navy (RNLN) started the Walrus class project in 1978. It was a project to build a series of four submarines, as a replacement for the four triple-hull submarines of the Dolfine class. The Dolfine was a unique Dutch design, dating from the 1950s, which for many years until 1992 determined the face of the Dutch submarine service. Construction of the planned first submarine in the class, S-802 Walrus, began when the keel was laid down October 11, 1979 by RDM (de Rotterdamsche Droogdok Maatschappij, Rotterdam, launched September 13, 1989 and commissioned March 25, 1992. The S-802 was first launched on October 26, 1985 but she experienced a serious fire in August 1986; the hull was undamaged but cabling and computers were destroyed. As a result, Zeeleeuw was to be the first submarine in service, with commissioning in 1989. The last of the class was commissioned in 1993.

Initial plans to build two more of this class were canceled in the 1989-1998 defense plan in favor of the Moray class. Moreover, the Ministry of Defense had previously announced that the two Zwaardvis class submarines will not be replaced by the two Moray class subs. The DFL44 million awarded to the RDM shipyard will be kept by the contractor, however. An opportunity to sell up to 10 submarines of this type to Taiwan had been emphatically stopped by the government. No further construction is anticipated.

Walrus features a double-hull configuration of advanced 'tear-drop' form. The hull dimensions are about the same as those of the Zwaardvis class (in services since the 1970's). The dive planes and rudders of the Walrus are unique because they are arrayed in an "X" configuration rather than a vertical-horizontal cross. The Walrus X-form after-plane configuration requires complex computerised control, and has not found favor with most other navies. A requirement to increase diving depth to 300 m led to the use of the French Marel high-tensile steel, and a reduction in the number of apertures and welded joints, in the hull. Use of new H.T. steel increased the diving depth by some 50 percent.

At the beginning of the design stage of the Walrus class submarine the RNLN required the reduction of crew - this has been reached, among other things, by adopting an extensive automation of not only data-handling, sensors and weapons, but also for platform control. Internal improvements over the Zwaardvis class include more powerful machinery; the Diesel-generators have SEMT-Pielstick PA4V200 twelve-cylinder engines, and these have a compressor at the free end to reduce sensitivity to exhaust back-pressure; the three sets are raft-mounted; the single propeller is driven by a double-armature motor.

The Walrus class submarines contain state-of-the-art electronics, the most sophisticated weapon systems and an integrated Sensor, Weapon and Command system (SEWACO). The greatest improvement over the earlier class is in the combat system; a control center below the fin houses the machinery-control and surveillance consoles and an advanced "Attack Center" for the data-handling and weapons control system. Because of the highly advanced platform computerisation and integration of weapon systems, these boats can be regarded as a new generation.

The 'Walrus' class, embraces already more than 2800 tons submerged displacement. Together with relative moderate battery capacity and extensive electronic equipment is seems that the design moved in a less desired direction. A submarine design of that size and with those electrical needs should have extra power means. One could get the impression - in view of the 'Walrus' dimensions and energy-consuming equipment - that the designers were not, or too late, acquainted with the fact that the main power source would not be of nuclear signature. An additional increase of about 200 tons, embodying an additional powerpack, seems more than justified not withstanding the increase in submerged displacement. The 'closed cycle diesel' installation, under development at the 'Rotterdamse Droogdok Mij'11, would give the 'Walrus' class that extra capability. This demands the insertion of a 'ccd' module of modest size.