SNLE 3G – French 3rd gen SSBN

Admin Alpha Mariner

On Friday, 19th February, the French Minister for the Armed Forces, Florence Parly, announced the launch of the full-scale development phase of the SNLE 3G program. This programme is a French third generation nuclear-powered ballistic-missile submarine.The launch ceremony took place at the French General Directorate of Armaments (DGA) hydrodynamics test center at Val-de-Reuil, Normandy, France.

As per the 2019-2025 Military Plan Law, the four Le Triomphant-class SSBNs have to be replaced with four third generation SSBNs (SNLE 3G) beginning in 2035. This will ensure the continuity of the French at-sea deterrence capabilities with a minimum of one SSBN on sea-patrol at all times.

Development Studies

Naval Group is the prime contractor for the overall production of the submarines, in a JV with TechnicAtome which is in charge of the nuclear boilers construction. The first contract will be awarded in 2021. It will cover the development studies until the end of 2025. It will cover the basic elements of the hull and the boiler room. Also, adaptation of industrial manufacturing means of Naval Group is on the agenda.


  • Length : 150 m
  • Displacement : 15000 T (submerged)
  • Crew complemet : 100 sailors
  • Weaponry:
    • 16 x modernized M51 SLBM (likely known as M51.4)
    • 4 x torpedo tubes for F21 heavyweight torpedo / FCASW next gen anti-ship missile

SNLE 3G Design Features Analysis


Similar to its predecessor SNLE 2G, this design also features a sail cusp. A sail cusp is a single composite fairing structure. It is attached to the submarine sail and hull. The main reason for introducing this is to obtain smooth laminar flow whicn implies a better hydrodynamic performance. This design features a pump jet. The stern incorporates a centerline fin for the towed array. Hence, it is reminiscent of the Suffren class SSN which has an X-rudder configurtion.


Since the entire nose comprises the sonar dome, it is indication of a very large spherical sonar array. Also the design indicates four torpedo tubes mounted behind the sonar dome. When we think logically, these must have outward angle for the torpedo to go around it. This indicates a limit on the launch speeds of torpedoes.


Only having four torpedo tubes is in line with the SSBN role, where the tubes are for self-defense. Any use of torpedo or anti-ship missile would mean a compromise on the patrol and the failure of deterrence mission.

The hull of SNLE 3G will have anechoic tiles, which consists of rubber or synthetic polymers. They help in absorbing the sound waves of active sonar as well as lower sounds emitted from the submarine itself. Hence, the French Minsiter for Armed Forces rightly said, “the third generation SSBN will be slightly longer and heavier compared to the Le Triomphant-class SSBN. So it will hear better and defend itself better, it will be quieter: it will not be noisier than a shoal of shrimp, which is absolutely exceptional. Hence, it will be able to blend in perfectly with the ambient sounds of the sea, which is a guarantee of operational superiority.

Major Suppliers

Sonar suite from Thales

The DGA has signed an MoU with Thales for the development of a complete sonar suite. It will include a broad range of sonar arrays and associated processing systems. These include new-generation flank arrays, bow-mounted sonars, towed linear array. The towed linear array is based on optical technology ALRO. In addition to these, they will also provide all other equipment that make up the sonar suite such as intercept arrays, echo-sounders, underwater telephones.

The array size and the use of Ultra low frequency bands will help in delivering unparalleled performance in terms of detection precision with regards to azimuth, elevation and range. This class will make use of the ALICIA (Analyse, Localisation, Indentification, Classification, Integration and Alerts) sensor data processing system. It has a user interface designed to handle the diversity and the volume of incoming data. It will optimise operator workload and provide decision support.

The French will install this suite on an incremental basis. First they will install it on SNLE 2G from 2025 onwards and in SNLE 3G from 2035.

Technicatome Nuclear Reactors

The nuclear reactor of Technicatome that will be used in this programme is called K22. This reactor willd eliver higher power. It serves as a link between the Baraccuda program and the reactor of the future PANG aircraft carrier. The design studies for this reactor commenced on December 8, 2020 post the decision from the French President.

Estimated Life Cycle

As per the schedule, the first steel cutting is in 2023. The plans are to deliver the first-in-class SSBN to the French navy by 2035. These submarines will be there in service till 2090.

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By Alpha Defense

Alpha Defense initially a solo venture but now a defense group by people from various demographics of India covering defense news and updates. We believe in unbiased analysis of every subject in hand. Our mission is to provide simplfiied defense information to the public.

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