Agosta 90B class submarines


The first Agosta will have AIP retrofitted while the remaining two will be built from kits supplied in Pakistan.Pakistani Agosta 90B subs will have the first application of the French SUBTICS integrated combat system.In brief this system integrates all acoustic and non-acoustic sensor inputs,weapons, navigation systems, command and weapon control systems on six twin screen consoles.Subtics sonar systems include a cylindricalbow array,flank array,active array,towed array,intercept array and obsyacle avoidance array.Above water sensors include search and attack periscopes, navigation radar and ESM. The Agosta 90B has 4 torpedo tubes and 16 weapon spaces for a mix of F17 Mod.2 torpedoes and Exocet SM39 Sub launched anti-ship missiles.Simultaneous engagement and weapon launch is possible for 2 missiles, or 2wire-guided torpedoes,or one ordinary torpedo and one missile.The MESMA AIP system allows for a fivefold or more endurance capability while submerged.Incidentally the German type 212 with a fuel-cell AIP can stay submerge for upto 2 weeks and can make 8kts without using her battery.

The `Agosta’ features a circular outer hull of 6.8 m maximum, which completely surrounds the pressure hull. At the bow the cross-section of the outer hull narrows to an oval shape, ensuring the minimum underwater hydrodynamic resistance. Considerable efforts have been made to reduce self-generated noise resulting in a clean, streamlined casing and noise damping of all equipment. An array of 36 hydrophones is fitted all round the hull to measure the radiated noise level and provide immediate identification of areas of self-generated noise. The boats are armed with four bow torpedo tubes fitted with a pneumatic ram discharge system. The tubes allow weapon discharge, irrespective of the speed of the submarine, down to its maximum diving depth. The design also incorporates a rapid reload system. Units of the French Navy have been modified to fire the Aerospatiale submarine-launched SM 39 Exocet anti-ship missile. The Pakistan units were modified to fire the Sub-Harpoon missile.


Fire control is exercised through a single, centralised computer using the DLA 2A system. This features an automatic navigational plotting system. Sensors include an 8 kHz active search/attack DUUA 2D sonar, passive ranging and passive towed array sonars. Arur and Arud intercept and warning systems are also fitted, except in the Spanish boats which are fitted with the British Manta system. The propulsion system comprises two SEMT-Pielstick 16 PA4 V 185 VG diesels developing 2.65 MW driving two Jeumont Schneider 1.7 MW alternators. A single water-cooled 3.4 MW electric motor with double armature directly drives the propellers. There is an intermediate clutch in order to reduce noise level to a minimum. In addition, a 23 kW electric motor is provided for cruise speeds. The two independent banks of batteries use an electrolyte agitation system with water circuit cooling to extend service life and improve efficiency. Hotel services are provided by two generators, the alternating current being provided by means of five converter sets with two solid-state inverters. The boats are equipped with oxygen generating units and independent CO_2 absorption units.


Submarine tactical integrated combat system.

Based on 20 years experience in the development of sonar subsystems (DMUX80, DSUV22, DMUX20, TSM 2233, TSM 2933) as well as command and weapon control subsystems (SYTAC, TITAC, LAT-NG), DCN and Thomson Sintra ASM (now Thomson Marconi Sonar SAS) have developed an integrated approach for both data analysis and system manning. Both companies have made extensive use of Commercial Off-The-Shelf (COTS) technologies and worldwide recognised hardware and software standards (such as workstations, power PC, UNIX, Ethernet) to further improve performance and simultaneously reduce production and life cycle costs of their equipments. Using this expertise, the two companies have together developed an efficient and competitive range of products named SUBTICS (SUBmarine Tactical Integrated Combat Systems) which is now being offered for both refit and new building submarine programmes. To achieve this objective and using the accumulated experience of both companies, DCN and Thomson Sintra ASM (now Thomson Marconi Sonar SAS) have established UDS International, a joint company in charge of manufacture and marketing of SUBTICS in France and on the export market.


The main subsystems of SUBTICS are:


  • (a) a comprehensive set of sensors which include: bow cylindrical or conformal arrays; towed arrays; and flank or distributed arrays that multiply the detection capacity of the submarine against silent targets
  • (b) all types of heavyweight wire guided torpedoes and fire-and-forget SM 39 Exocet missiles which together cover an action area out to 40 km
  • (c) an integrated architecture which links both sensors and weapons to the system’s communication and data handling core through the databusses of the system network.
  • The core of SUBTICS is an open and modular architecture based on standard data processors (TMS 320 C30 processors on a speed ring network), redundant databusses and six multifunction common consoles equipped with two high definition 19 in colour monitors. The dual redundant Ethernet databus offers reliable and continuous communications in the event of damage, the multifunction common consoles allow manning and configuration flexibility, and together they provide function and data operational availability. The choice of an open structure, together with the standard and sizeable processing and display resources, allows existing or new operational components to be easily integrated with minimum life cycle costs.

    The Agosta 90B SUBTICS control room.

    The basic components of the sonar subsystem include a set of acoustic arrays and appropriate detection (or transmission), tracking, and analysis and localisation processing modules, together with a set of common processing modules for contact motion analysis, classification, identification and track management using broadband, narrowband, demon and pulse (passive interception and ranging) processing channels.

    The basic set of acoustic arrays includes a cylindrical or conformal bow array, an active array, a distributed array, an intercept array, a towed array, a flank array, and optionally an obstacle avoidance array. The contact motion analysis module includes automatic and interactive processing functions. The classification and identification module includes audio and spectrum analysis processing functions plus interactive hypothesis generation and verification functions. The track management module includes interactive association and fusion processing functions plus sorting of best representative acoustic track functions. The basic components of the command and weapon control subsystem include a set of situation elaboration modules, a set of command and decision modules, and a set of engagement and launching modules. The set of situation elaboration modules includes acoustic and non-acoustic sensors track association and fusion functions, interactive target motion analysis functions, and track management functions able to sort out tracks of particular tactical interest among a set of 100 recorded tracks. The set of command and decision modules includes threat evaluation of localised and classified tracks, plus attack and escape manoeuvre planning tools.

    Engagement and launching modules give the submarine capacity to launch simultaneously two torpedoes in wire guided mode, plus either two SM 39 Exocet missiles or one non-wire guided torpedo and one missile. Operational performances are primarily related to SUBTICS’ sensors and weapons capabilities, which multiply the detection and action area of the submarine. Performance is further enhanced as a result of the fully integrated architecture of SUBTICS. This means that as a result of full integration every element, either data processing, computers or multifunction common consoles, are connected to redundant databusses. As a result the system’s processing functions and the operators are offered unique accessibility to all information, together with a unique availability of information due to reconfiguration capabilities and redundancies.

    SUBTICS full integration also means that every operational function is coherently associated in a continuous track building process along which tracks are continuously summarised and displayed together with their associated localisation and classification attributes. As a result, clear and comprehensive tactical situation displays are presented allowing the command to take fast, accurate and correct decisions. With adaptability and evolutionary requirements in mind, SUBTICS can be fitted on any type of submarine both for new construction as well as for modernisation programmes. The system responds to the present and future operational needs.

    Three systems were ordered in early 1995 for Pakistan’s new `Agosta’ boats and are currently being assembled.

    The `Agosta 90B’, building for Pakistan are fitted with the DR-3000U ESM system and the Subics Mk 2 integrated combat suite. The last boat in the series will be fitted with the MESMA AIP system (which will extend the hull length by 9 m). This system will also be retrofitted to the first two boats in the series. These units will also have much improved acoustic quieting and a fully integrated sonar suite including flank, intercept and towed arrays. The hulls are being constructed of HLES 80 steel which should allow them to reach diving depths of 350 m.


    Number Name Builder Laid Down Launched Commisioned
    S137 Khalid DCN, Cherbourg 1997 1998 September 1999
    S138 Saad DCN, Cherbourg/
    Karachi Dockyard
    1998 2001 August 2002
    S139 - Karachi Dockyard 1999 2002 Oct 2002

    DISPLACEMENT, tons : 1,570 surfaced; 1,760 dived (1,960 with MESMA)
    DIMENSIONS, ft (m) : 221.7 x 22.3 x 17.7 (67.6 x 6.8 x 5.4)
    MAIN MACHINERY : Diesel-electric; 2 SEMT-Pielstick 16 PA4 V 185 VG diesels; 3,600 hp(m) (2.65 MW); 2 Jeumont Schneider alternators; 1.7 MW; 1 motor; 4,600 hp(m) (3.4 MW); 1 cruising motor; 32 hp(m) (23 kW); 1 shaft
    SPEED, knots : 12 surfaced; 20 dived
    RANGE, miles : 8,500 at 9 kt snorting; 350 at 3.5 kt dived
    COMPLEMENT : 36 (7 officers)
    MISSILES : SSM: Exocet SM 39 may be carried.
    TORPEDOES : 4 – 21 in (533 mm) bow tubes. Up to 20 F17P Mod 2.
    MINES : Stonefish.
    COUNTERMEASURES : ESM: Thomson-CSF DR-3000U; intercept.
    WEAPONS CONTROL : Thomson Sintra SUBICS Mk 2.
    RADARS : Surface search: I-band.
    SONARS : Hull-mounted bow and flank arrays. Towed array.

    PROGRAMME : A provisional order for a second batch of three more Agostas was reported in September 1992 and this was confirmed on 21 September 1994. First one building in France, final assembly of second in Pakistan from March 2001, and the third to be built in Pakistan. STRUCTURE : Exocet is being negotiated. The last of the class is planned to have a MESMA liquid oxygen AIP system which would extend the hull by 9 m, if it is fitted. Hulls will also have much improved acoustic quietening and a full integrated sonar suite including flank, intercept and towed arrays. HLES 80 steel should allow diving depths of 350 m (1,150 ft).

    OPINION : This is an ambitious programme, given the unhappy history of licence-built submarines in other medium-sized navies. The introduction of AIP is also ambitious and likely to be costly. Shipbuilders understandably downplay the risks of introducing this new technology and the Pakistan Navy is an experienced operator of submarines. Nonetheless, the operational advantages of AIP have to be balanced against potential technical risks.

    DISP.SURFACED (tonnes) :1595.0
    DISP.DIVED (tonnes) :1788.0
    LENGTH (m) : 67.60
    BEAM (m) : 6.8
    DRAUGHT (m) :5.4
    SPEED (knots) : 20.0
    RANGE (nm) : 8500.0







    Name No Builders Laid down Launched Commissioned
    S 135 Dubigeon Normandie,
    15 Sep 1976 14 Dec 1977 17 Feb 1979
    S 136 Dubigeon Normandie,
    18 Sep 1977 1 Dec 1978 18 Feb 1980

    DISPLACEMENT, tons : 1,230 standard; 1,510 surfaced; 1,760 dived
    DIMENSIONS, ft (m) : 221.7 x 22.3 x 17.7 (67.6 x 6.8 x 5.4)
    MAIN MACHINERY : Diesel-electric; 2 SEMT-Pielstick 16 PA4 V 185 VG diesels; 3,600 hp(m) (2.65 MW); 2 alternators; 1.7 MW; 1 motor; 4,600 hp(m) (3.4 MW); 1 cruising motor; 31 hp(m) (23 kW); 1 shaft
    SPEED, knots : 12 surfaced; 20 dived
    RANGE, miles : 8,500 at 9 kt snorting; 350 at 3.5 kt dived
    COMPLEMENT : 54 (7 officers)

    MISSILES : SSM: Aerospatiale SM 39 Exocet; launched from 21 in (533 mm) tubes; inertial cruise; active radar homing to 50 km (27 n miles) at 0.9 Mach; warhead 165 kg.
     4 – 21 in (533 mm) bow tubes. ECAN L5 Mod 3; dual purpose; active/passive homing to 9.5 km (5.1 n miles) at 35 kt; warhead 150 kg; depth to 550 m (1,800 ft) and ECAN F17 Mod 2; wire-guided; active/passive homing to 20 km (10.8 n miles) at 40 kt; warhead 250 kg; depth 600 m (1,970 ft). Total of 20 torpedoes and missiles carried in a mixed load.
    MINES : Up to 36 in lieu of torpedoes.
    COUNTERMEASURES : ESM: ARUR, ARUD; intercept and warning.
    WEAPONS CONTROL : DLA 2A weapon control system.
    RADARS : Search: Thomson-CSF DRUA 33; I-band.
    SONARS : Thomson Sintra DSUV 22; passive search; medium frequency.
    DUUA 2D; active search and attack; 8 kHz.
    DUUA 1D; active search. DUUX 2; passive ranging.
    DSUV 62A; passive towed array; very low frequency.

    PROGRAMME : Building of this class was announced in 1970 under the third five-year new construction plan 1971-75.
    MODERNISATION : Included fitting of SM 39 Exocet and better torpedo discharge and reloading. Completed in 1987.
    STRUCTURE : First diesel submarines in the French Navy to be fitted with 21 in (533 mm) tubes. Diving depth, 320 m (1,050 ft). Has twice the battery capacity of the `Daphne’ class.
    OPERATIONAL : All based at Brest from 1 July 1995 and assigned to GESMAT (Groupe des Sous-Marins d’Attaque de l’Atlantique). Endurance, 45 days. One paid off to reserve in January 1997, S 621 to follow in February 1998, and S 622 in 1999. S 623 to remain in service as a trials ship until 2005.

    SALES : Four built at Cartagena for Spanish Navy and two for Pakistan by Dubigeon, with three more for Pakistan ordered 21 September 1994.

    DISP.STANDARD (tonnes) :1249.0
    DISP.SURFACED (tonnes) :1534.0
    DISP.DIVED (tonnes) :1788.0
    LENGTH (m) : 67.60
    BEAM (m) : 6.8
    DRAUGHT (m) :5.4
    SPEED (knots) : 20.0
    RANGE (nm) : 8500.0

    TSM 2225 Panoramic surveillance and direct passive ranging sonar.


    The TSM 2225, which is a module of the TSM 2233 sonar system, consists of a set of six arrays (three on each side of the submarine), one cabinet and one console. The sonar performs panoramic surveillance and pulse interception, target and automatic pulse tracking and ranging, and target localisation.
    Simultaneous tracking on up to eight noise sources and eight sonar transmissions is carried out using Lofar, Demon and pulse mode analysis.
    TMS 320, C30 and 68040 microprocessors are used for signal processing as in the TSM 2233 (see previous entry) and data is handled in the same way as in the TSM 2233.

    Operational status

    The TSM 2225 is the latest version of the DUUX 5 and is installed on the Australian `Collins’ class and Pakistan Navy `Agosta’ class submarines.

    TSM 2233 Submarine passive and active sonar system.


    The TSM 2233 is a modular, integrated sonar system designed to fit any size of submarine and to fulfil any operational requirement. The system includes any or all of the following acoustic sensors: linear towed array, flank arrays, bow array (cylindrical or conformal), intercept array, distributed arrays, active array, obstacle avoidance array.
    The TSM 2233 sonar system provides the following set of functions: Passive detection
    Broadband, narrowband and transient processing are concurrently performed so as to match with the noise characteristics of any vessel. For each operational function, sonar data from the various arrays and processing are gathered and associated to reduce the operator workload while maintaining maximum sensitivity. Automatic anti-jamming
    The anti-jamming feature automatically rejects narrowband jammers, thereby hardening tracks and enhancing Contact Motion Analysis (CMA) performance (range, accuracy and convergence delay). Passive adaptive processing The adaptive processing function is based on an optimal array processing theory which minimises the effect of jamming by strong signals when listening to low-level signals. It is a particularly useful facility in discriminating between two targets in a common limited sector. Automatic detection and tracking By automatically initiating tracks, this feature allows the operator to avoid repetitive tasks so that he can deal with more complex situations.


    This function allows interception of all active sonar pulses from low-frequency surface ship sonars to high-frequency torpedo acoustic heads. Very early warning of hostile sonars with a low false alarm rate is provided. Interception warnings are integrated on the passive listening scope. Accurate parameters of pulses are presented on digital readouts.

    Active capability

    Although initial bearings are provided by the passive detection function, the operator can select the active mode to determine range accurately. In this mode, reception is performed by the passive listening array, and is associated with high-detection sensitivity.


    The spectrum analysis facility (Lofar and Demon) complements the audio function by providing the operator with specific data in target classification, which is computer-aided through an interactive database.

    Hostile weapon alarm

    A specific algorithm sorts out the contacts taking into account various target parameters and warns the operator in the event of a hostile weapon.

    Contact Motion Analysis (CMA)

    Contact localisation and motion analysis of contacts are performed automatically on all tracks. Key features of the system are: modular signal processing which makes it possible to adapt the configuration to suit new vessel designs and modernisation (possibly keeping existing arrays); reduced operator workload due to the high level of automation of the detection, tracking and localisation functions; and the flexibility and ease of adaptability to submarine size and mission requirements resulting from the coherent set of complementary sensors. The system uses TMS 320, C30 and 68040 microprocessors for signal processing in MIMD-type host systems communicating internally across high-speed ring networks and externally on standard VME-type buses. The system uses structured software developed in C and Ada. Multifunction workstations are used with one or two high-definition 19 in colour monitors (Colibri or MOC consoles).

    Operational status

    TSM 2233 is the latest generation of the well-known Eledone family, some versions of which are in service in the French Navy (DSUV 22 for the `Rubis’ class), the Royal Navy (2040 Argonaute on Upholder), the Royal Netherlands Navy (`Walrus’ class) and the Spanish Navy (`Agosta’ and `Daphne’ classes).
    Various versions of the TSM 2233 are installed on the Royal Australian Navy’s `Collins’ class, the Pakistan Navy `Agosta’ and `Daphne’ classes and French Navy `Amethyst’ class (DMUX 20).