Agosta class submarine (1977)

Conventional Attack Submarines (S-620 to S-323). Agosta, Bézévier, La Praya, Ouessant. Service: 1978-2009.

French Cold War Submarines

La Creole class (1940) | Narval class (1954) | Arethuse class (1957) | Daphne class (1959) | Gymnote test SSBN (1964) | Le Redoutable SSBN (1967) | Agosta SSN (1974) | Rubis SSN (1979) | Amethyste SSN (1988) | Le Triomphant SSBN (started 1989)

Next in the cold war French submarine lineage are the last French conventional design, the Agosta class. All were named after naval battles, starting with the battle of Augusta in 1676. Developed and constructed by DCNS in the 1970s to to succeed to the Daphné-class they were much improved with a completely new hull and massive sound-proofing. It proved successful at export as well, with 13 built, 4 in service with French Navy, 4 in Spain and 2 for Pakistan (plus later three 90B variants) and by Royal Malaysian Navy for the training. They were succeeded in France by the Rubis-class SSNs, but are still in service in Spain and Pakistan. Unlike the previous Daphne they were class as “sous-marin d’attaque océanique”, (“ocean-going” attack subs). In many ways, their hull was converted to nuclear power to create French first SSNs, also the world’s smallest at the time.

Development of the Agosta class

Larger than the Daphné-class, the Agostas were designed to carry out long-range missions, hence the “oceanic” title. However they were NOT tasked to escort French SSBNs from Long Island in Brest out in the Atlantic. They were designated as long range sub-hunters, replacing the Arethuse class, but optionally intercept any possible threat to French SSBNs along their initial patrol route or protect French Carrier Battle Groups. Emphasis was put in external and internal noise sources reduction, as much as possible with the French tech at the time. They notably had retractable hull fittings, a new sound-absorbent rubber coating, refined hull shapes and allegedly, some powerplant rafting. Also improved on the previous Daphné class were their four automated torpedo tubes, for quick-reloading. They could launch either 550 mm (French standard) or 533 mm (British standard) diameter torpedoes as well as later the encapsulated Exocet SM39 missiles and mines. The Daphne class were scheduled for replacement by the Rubis class SSNs, and tasked with the protection of French SSBNs.

A brand new generation of attack submarines, and the last conventional French ones. The Agosta class were of double hull construction as the second hull was used for ballast, storage fuel and auxiliary tanks plus sensing heads for the acoustic suite. The outer shell had a cylindrical section refined as ellisptic at the front for better penetration, but it was still not fully “droplet” shaped. Design was made from the mid-1960s, alreay when the last of the previous Daphne class were launched. The final design came in 1971 and construction started in November 1972 for the first, Agosta, at Arsenal de Cherbourg like the others and the Redoutable class SSBN. Too small to carry nuclear reactors, the Agosta were conceived, not as escorts of SSBNs from Ile Longue (Brest), but hunter-Killers for the Mediterranean, replacing the 1950s Arethuse class.
Nevertheless, they were well profiled and streamlined, much better than previous French subs, with recesses for deck fittings for a better waterflow. The diving planes were close to the bow, and there were no additional ones on the fin. But there were cross controls aft.

Agosta-Class SSK From Pinterest

The sensor suite comprised DUUA2 search and DSUV 22 passive array plus a crown of 36 hydrophones to provde a bearing on enemy noise emissions. The DSUV 62A towed array completed the suite by providing a large detection range. Torpedo tubes were reduced in number thanks to a new generation of vector, the L5/F17 wire-guided torpedo which had a high hit probability rate. The vector was discharged by a pneumatic ram, performed at any depht or speed. The tubes were large enough to accept 550 mm torpedoes as well. The boats were provided with the DLA D3 Fire control system.

La praya post launch at Cherbourg, later fitted out in Brest. (seaforces.com)

The Agosta (S620) was completed in 1977, Bezeviers the same year and date, while La Praya was completed in March 1978 and Ouessant in July 1978. Bézéviers became the tst boat for the new SM39 Exocet encapsuled torpedo missile. In the late 1980s, the three others were retrofitted this way. The four boats of the squadron served until the mid-1980s and were transferred in the Atlantic to replace the Narval class. The design attracted orders: Two were buit for South Africa (later resold to Pakistan), and four were built under licence by Spain for the Armada, completed in the 1880s. The Agosta class were the base for the Rubis class SSN (“SNA” in French).

Design

Compared to the Daphne class, still “classic” in their hull shape, the new Agosta hull was much refined in tests pools and further streamined, taking notably in account the studies made on the earlier Redoutable class SSBNs. Their length was ported to 76.24 m (9 m extension compared to the Daphne) for a displacement increased to 1,730 tonnes surfaced, 1,980 tonnes submerged. They introduced the brand new Combat system SUBTICS, from UDSI (later DCNS), and TSM 2253 active sonar. They carried 16 weapons on board, torpedoes or mines and later encapsulated missiles. Heavy automation enabled to reduce the crew to just 36 officers and ratings and her propulsion system was geared towards long range and greater underwater speeds. Choice was made of two 850 kW SEMT Pielstick 16 PA 4 generators and one 200 kW MESMA auxiliary engine for an autonomy allegely increased fivefold compared to the Daphne.

Hull and general design

From Pinterest src
The hull was made in the new 80 HLES steel, enabling for a maximum immersion depth of 320 m (1050 ft). The general hull design was round in section but still ended with a narrow prow as past designs instead of a more conventional dome-like prow, but rounder than past designs. This shape was believed to help water penetration and improved stability at high speeds, or surfaced. But it had consequences notably in the space allocated to the fixed hull sonar. The end was more conventional and ended with a cross type stern rudder and tail. The upper part of the hull was flattened for stability when walking up. These were two fully retractable diving planes forward rather than on the sail, which still had an outer covered bridge and open bridge behind and above. There was a filler line at the base of the pressure hull, at the base of the prismatic end making the outer upper hull, plus several rows of limber holes forward.

Powerplant

It was more powerful thanks to the longer hull compared to the Daphne, comprosing two diesel generators (“groupes électrogènes”) SEMT Pielstick 16 PA 4 rated for 850 kW and an auxiliary backup unit MESMA rated for 200 kW. Batteries power consisted in 320-cell battery with twice the capacity of the previous Daphne class. There was also a small 32 hp “creep” motor for silent operations, giving a top speed of 3.5 knots.
Top speed was 12 knots (22 km/h; 14 mph) surfaced, 20.5 knots (38.0 km/h; 23.6 mph) submerged, 10.5 knots (19.4 km/h; 12.1 mph) submerged (snorkeling).
To be precise, a top underwater speed of 17.5 knots was sustainable for one hour, and 20.5 knots for 5 minutes, with a boost for evasive action.
Compared to 13.5 knots surfaced, 16 knots submerged for the Daphne class, this was quite an improvement indeed. As for range, the Agosta class carried 185t of diesel oil for an Endurance of 8,500 nautical miles at 9kts under snorkel or 280 nautical miles at 3 knots submerged. The Daphne class was capable of 4300 nm (8,000 km; 4,900 mi) 7.5 knots snorkelling, with an autonomy 30 days. The initial 2-ton bronze propeller was 5-bladed, measuring 2.7 m in diameter. It was changed on the Agosta 90B for a silent, hooked, 7-bladed model.

Armament

L5 Acoustic Torpedo

The 553 cm L5 entered service in 1971 (mod 1-3) and in 1980 the mod 4. They had a better range than the L3 at 7000 or 10,000 yards at 35 knots depending on the mods, carrying the same 440 lbs. (200 kg) HBX-3/TNT payloads but with better acoustic search range and resistance to ECM and decoys.
⚙ specifications 53 cm L5
Weight: 2061 lbs. (935 kg), 170.1 in (4.320 m) lenght.
Warhead 440 lbs. (200 kg) HBX-3 or TNT
Power: Silver-zinc Battery
Range/Speed settings: Mod 1/3: 7,700 yards (7,000 m)/35 kts. Mod 4: 10,000 yards (9,500 m)/35 kts

F17 Mod 2 Wire guided Torpedo

This was essentially the first French Wire-guided dual-purpose torpedo, using also a active-passive terminal homing when the cable was dropped.
They evolved with the Daphne class.
⚙ specifications 55 cm F17 M2
Weight: 3,108 lbs. (1,410 kg), lenght 236 in (6 m long) x 55 cm
Warhead: 551 lbs. (250 kg) HBX-3
Propulsion: Zinc-silver oxide batteries for a base 19,700 yards (18,000 m) at 35 knots, 31,700 yards at 24 kts under wire.
Specs: 323 in (5.900 m) long, range/speed 22,000 yards (20,000 m)/35 knots.
The F17P Mod 2 introduced in 1985 was longer at 221 inches (5.62 m) for 32,000 yards (30,000 m) at 35 knots.
The improved Mod 2 arrived in 1988 and was shorter at 212 inches (5.384 m) long, for 22,000 yards (20,000 m) at 40 knots.

SM 39 Exocet

In 1985-1987, all were capable launching the SM39 Exocet SSM (Each carrying four SM39). Target range and data are downloaded before launch into the Exocet’s computer. It follows a sea-skimming course using inertial navigation and active radar homing close to the target at Mach 0.9 over 50km. The 165kg high-explosive shaped-charge warhead is designed to penetrate the enemy vessel, explodes inside and create a large fire, difficult to master and potentially fatal.

Sensors

Thomson CSF DRUA 33 Radar
Thomson Sintra DSUV 22C sonar suite
DUUA 2D Sonar
DUUA 1D Sonar
DUUX 2 Sonar
ETBF DSUV 62A towed array
ECM: ARUR and ARUD detectors
Fire Control: DLA 2A suite
In 1988-1991, all were upgraded, with the removal of the DRUA-33 radar, DUUA-1D sonar, ARUR ECM suite and replacement by a DRUA-33C radar, DSUV-22C, DSUV-62A towed array sonars, and ARUR-12 ECM suite. Note, if available i will detail ranges and caracteristics of these sensors.

Conway profile

Variants

Agosta 70

Basicaly the initial version intended for the French and Spanish Navy (see the specs above).

Agosta 90B

From Pinterest
The Agosta class were already in the Pakistan navy as the Agosta 70, and the 90B was designed at first as an upgrade featuring higher performance and a new combat system, a longer and stronger hull. Three Agosta 90Bs were ordered by the Pakistan in September 1994 with Khalid (S137) built at DCN in Cherbourg and commissioned in 1999. Under constract and tech trtansfer, the two others were built in Pakistan with French assistsance. Saad was thus assembled at Karachi Naval Dockyard, launched in August 2002, commissioned in December 2003. Hamza was launched in August 2006 and commissioned in September 2008. The delay was due to the terrorist attack of May 2002, killing 11 French engineers in Karachi. This delay was used to integrate the new MESMA air-independent propulsion system (AIP). Hamza had successful acceptance trials and by March 2007, Pakistan placed an order with DCNS to retrofit the first two with the MESMA AIP which was done by December 2011. A license was offered by DCNS to offer commercial production to potential customers.

The Agosta 90B submarines differs by their modern SUBTICS fully integrated combat system from UDS International (joint subsidiary of DCN International and Thales). This system processes signals from all sensors, determines a tactical situation and display by data fusion as well synthesis and predictive plotting and weapons management for C3R. The 90B still have 16 torpedoes and missiles unlike the previous Pakistanu boats which had 12. It istill operated the F17 mod 2 torpedo, Exocet SM39 missile. The 90B are provided with the Thales DR-3000U radar warning receiver (D-K bands) with a masthead antenna array and omnidirectional/monopulse directional antennae, separate periscope warning antenna. The Thales Underwater Systems TSM 223 sonar suite includes the bow-mounted sonar, towed sonar array. The two periscopes are a SAGEM with the navigation system plus a Thales I-band navigation radar and the combat, low-visibility IR periscope. As sais above the propulsion now integrates the MESMA AIP, the rest being the same SEMT-Pielstick diesels rated for 3,600hp plus a 2,200kW electric motor. The propeller was new, with 7 blades. The AIP enables these ti remain submerged three times longer.
Each MESMA system comprises a turbine receiving high-pressure steam from a combustion chamber burning an ethanol/liquid oxygen mix. This needed a new section and thus, an overall lenght ported to 76m and 2,050t submerged. These had been modernized by Turkey in 2021-22. They are expected to remain in service FY2035.

General evaluation

Four Agosta-class submarines were built at the Cherbourg arsenal for the French Navy’s submarine forces under the 1970-1975 program law. Decommissioned between 1997 and 2001, they were the last conventionally powered submarines in the French Navy. They were replaced in France by the nuclear-powered Rubis class.
The last of the series, Ouessant, was rearmed in 2005 after a transformation at Brest arsenal for loan and transfer to the Royal Malaysian Navy. The latter purchased later two Scorpène-class submarines from the DCNS/IZAR consortium. She was used to training its crews at Brest with the assistance of NAVFCO. Once training was completed in 2011, Malaysia transported the vessel on a barge, and converted her into a museum ship where she can be visited today.

The hull of the Agosta was used in the 2010s as a shock chamber for experiments conducted by the Directorate General of Armaments in Toulon.
In August 2019, Navaleo, a subsidiary of “Les Recycleurs bretons” was awarded a contract to dismantle the Agosta, Bévéziers, and La Praya, be completed by 2022 at Brest shipyard. The propeller from the last hull to be dismantled, was transferred at the French Navy’s Fleet Support Service in April 2022, exhibited at the grounds of the Brittany Regional Council headquarters in Rennes.

The Agosta class from 1977 to 1997 prepared the arrival of nuclear-powered attack submarines in the fleet. They were an important step, mostly in sound-proofing, which was important for the 1980s standards in a fierce underwater competition. British, US submarine established a new standard in silent running, and Soviet submarines rapidly caught up as well. Albeit not perfect still, the Agosta class were quickly catalogued by their quieter competitors. They were still important to define many features later ported to SSNs, developed quickly thanks to the existing hull. The class as a whole was seen as sufficiently attractive to gather international orders, notably through technology transfer.

The class also prepared the way for future export submarines such as the new Scorpene class, derived from the 2nd generation French SSN. Today, Naval Group market its Barracuda class as a larger successor of the Scorpene, diesel-electric with AIP propulsion. After AUKUS in 2021 and a lost contract to Australia, Naval Group signed with the Netherlands in 2025 and negotiations goes on with India and other potential buyers. So the French conventional submarine lineage is far from over.

Career of the Agosta class

Agosta in Rouen 1994

Agosta was ordered from the Cherbourg shipyard. Her keel was laid on November 1, 1972, she was launched on October 19, 1974, completed on July 28, 1977.
She remained in service from 1977 to 1997. Initially assigned to the Mediterranean Submarine Squadron (ESMED) in Toulon, was assigned to Kéroman base in the summer of 1986, with the Atlantic Submarine Squadron (ESMAT). In the summer of 1995, she left Lorient for Brest and ended her career with the Atlantic Submarine Group (GESMAT). She was decommissioned on February 28, 1997, placed in special reserve, prior to full deactivation.
She temporarily returned to service at the end of 2003 for the Condock IV renovation program at Toulon, for shock test at the Naval Systems Technical Center, providing valuable lessons for the design of future generations of submarines. Likewise, she was dismantled at Navaleo in Brest. The French Navy donated her bronze propeller to Brittany Regional Council in April 2022 where it is in display.

Bévézier (after the battle of Beachy Head in 1690) was ordered from Cherbourg, laid on May 17, 1973, launched on June 14, 1975, completed on July 29, 1977.
Initially assigned to the Mediterranean Submarine Squadron (ESMED) in Toulon, she was based at Kéroman in the summer of 1984, and the Atlantic Submarine Squadron (ESMAT). In the summer of 1995, she left Lorient for Brest, decommissioned in 1998. She was stored at the Brest Arsenal from 2009 to 2020 awaiting disposal, done in Brest on 2020-2021.

Named after the battle of La Praya (Porto Praya 1781, part of the American revolution) was laid down in November 1974, launched on May 15, 1976, and entered active service on March 9, 1978. Third inserie she was at first assigned to the Mediterranean Submarine Squadron (ESMED) in Toulon. She notably made a five-month deployment to the Indian Ocean in 1983. In 1985, she fire and validated the use of the sub-launched Exocet SM39 missile before being assigned to the Atlantic Submarine Squadron (ESMAT), in Lorient in 1986. She was however back to the Mediterranean in 1991 to participate in the Gulf War.
In 1995, with her sisters she joined Brest and GESMAT (Atlantic Submarine Group). She yearly performed six-month missions. One brought her to China Sea in 1998, for the Lumut Naval Exhibition in Malaysia (and securing a contract). She also served in the Baltic Sea (1999) and three more months in the Caribbean.
In 1985 in a famous TV commercial for Citroën, she “recovered” a Visa car already catapulted from the carrier Foch. She was decommissioned on July 1, 2000, but only deactivated on June 30, 2009, stricken, with her stripped hull saying at the Brest naval base on July 11, 2000 as Q 835. She cranked up 326,000 nautical miles (31,000 hours underwater) for 22 years of navigation. Furthermore, she had been scrapped since 2022.

Also named after a Battle (Ushant 1778) Ouessant was launched at Cherbourg in 1974, she was launched on October 23, 1976, commissioned on July 23, 1978 for the battle centenary. She had a shake down from May 5 to July 5, 1978, and her first mission Operation Okoumé, which started on January 17 to May 7, 1979 in Africa, first of such deployments since a long time, supported by the BSL Rhône. She took part in Operation Kessel from January 4 to February 9, 1982 and Operation Achenar from February 27 to July 16, 1984 in the Indian Ocean, via Djibouti, Karachi, and Port Safaga, making the first French underwater crossing of the Red Sea to the Hanish Islands.

From July 31 to August 26, 1985 she took part in Operation Matisse via Al Huceima in Morocco to test a new very low frequency (VLF) sonat to intercept two Soviet nuclear submarines in the vicinity. Next she was in Operation Fusain, from January 25 to March 1, 1991 as part of the Gulf War operations, earning a recommendation from Vice Admiral Henry H. Mauz Jr. (“Hank” Mauz), Commander 7th Fleet COMUSNAVCENT.
She made a long deployment to the Canary Islands in 1994 to evaluate the DSUV 62A sonar, and in the Mediterranean from March 6 to May 14, 2000 in addition to many classified intel and interception missions. She also assisted a drifting cargo ship off Ar-Men in 1991.

As the last French conventional submarine, she was decommissioned on July 13, 2001, after 23 years of service (33,637 diving hours, 338,681 nautical miles).
Mothballed, she was reactivated in 2005, and had a refit in Brest for a training loan to the Malaysian Navy which had purchased two Scorpène-class submarines, signed on December 28, 2002, effective on October 30, 2003. Training started from November 21, 2005, to 2009. Placed in reserve on August 1, 2009, she was transferred to Malaysia and was converted into a museum at Klebang, Malacca. Apart the Turkish Agosta, she is the only Agosta 70.

Exports

On 10 September 1974, South Africa announced its submarine expansion program and entering in discussion with France to acquire the Agosta-70 and replaced its Daphne class left by PM P. W. Botha as Capt. L. J. Woodburne as project-manager. Dubigeon-Normandie was the contractor, but later France denied delivery to South African Navy following Resolution 418 of the UN installing an arms embargo over its Apartheid policies.

In 1978, Pakistan purchased two Agosta 70 originally intended for the South African Navy, but denied due to its apartheid policy. These Agosta-70A class prepared for South Africa were repurchased after modifications by Pakistan and commissioned in 1979 as the Hashmat Class. In 1983–1985 they were deployed in the Arabian Sea to deter actions from a large Indian Navy. They were deployed on long-range mission to test depth and endurance in the Indian Ocean. They are still active, at the Jinnah Naval Base (from 2014).

The Pakistani Navy ordered in addition of their Agosta 70, three Agosta 90Bs sold for €825 million in 1994. The first Agosta 90B was built by DCNS Cherbourg, the other two were in Karachi with French technical assistance. S139 had the Mesma AIP engine latter retrofitted in 2004. They were recently upgraded by Turkey, at the engineering company STM in 2021-22.

The Spanish Navy built four Agosta submarines in the early 1980s with French technical assistance, using French electronic equipment and French L5, F17, and E18 torpedoes.
Class:
-Galerna (S 71), Completed 1983, in service (TS).
-Siroco (S 72) Completed 1983, Decommissioned 2012.
-Mistral (S 73) Completed 1985, Decommissioned 2020.
-Tramontana (S 74) Completed 1985, Decommissioned 2024.

Mistral in Overhaul

Read More/Src

The only preserved Agosta 70 now in Malaysia (pinterest)

Books

Conway’s all the world fighting ships 1947-1995 p122.
Darman, Peter, ed. (2004). 21 Century Submarines and Warships. Military Handbooks. Grange Books.
Miller, David; Jordan, John (1987). Modern Submarine Warfare. New York: Military Press.
Miller, David (1989). Modern Submarines. Combat Arms. New York: Prentice Hall Press.

Links

netmarine.net agosta/
navypedia.org fr_ss_agosta.htm
https://www.globalsecurity.org/ Al Khalid class
babriet.tripod.com/ agosta 90
militaryfactory.com agosta class
forecastinternational.com/
seaforces.org Agosta-class.htm
naval-technology.com/ agosta/
en.wikipedia.org Agosta-class_submarine
navweaps.com/ FR torps
facebook.com/ agosta-class
on navalnews.com/
on commons.wikimedia.org/
on fr.wikipedia.org/
x.com/800Tonnes/
navalnews.com/?s=agosta
armedconflicts.com Siroco-S-72
shipspotting.com/photos/1334345
babriet.tripod.com agosta70.htm
jotarofootsteps.blogspot.com

Videos

Model Kits

super-hobby.com Modern-diesel-Agosta
super-hobby.co.uk/ Agosta-Class
super-hobby.com/ S620-AGOSTA

3D

on grabcad.com/