4700-Ton French Nuclear Attack-Submarine ‘De Grasse’ Leaves Cherbourg Port For Sea Trials

French naval submarine De Grasse, powered by nuclear energy, is moving to sea for the first time.

The nuclear submarine left Cherbourg Port on February 24, 2026, to undergo trials to test its propulsion systems, combat systems and reactor performance under different operating conditions.

The development is a part of the French Navy’s Barracuda program, which aims to replace the old Rubis-class fleet and develop a new and advanced stealthy submarine force in the coming decade.

The submarine’s pressurised power reactor was activated in December last year, inching it closer to deployment.

De Grasse & Barracuda Program

The De Grasse is the 4th Barracuda-type attack submarine of the French Naval forces, built under the Suffren-class program to replace the Rubis-class vessels of the 1980s.

Under the program, the defence procurement agency ordered 6 submarines: Suffren, Duguay-Trouin, Tourville, Rubis and Casabianca.

The first three entered service between 2022 and 2025, and the other two are being constructed and are slated for delivery by 2030.

De Grasse was launched in May 2025 and underwent trials in assembly facilities and dry dock before it was given a go to enter the open waters for the final set of tests.

French defence firm Naval Group said that these submarines are designed to meet the needs of today and tomorrow. They are versatile, offer high-performance and are heavily armed compared to their predecessors.

Their service life is estimated to be more than 30 years, and the program is said to revamp the French submarine fleet till 2060.

Hundreds of subcontractors are part of the production process, and once delivered, these submarines will form the core of the French submarine attack fleet, enhancing stealth, offering longer endurance and greater combat capabilities.

Technical Specifications of the Submarines

Each submarine is 99 m long, has a 9 m diameter and can dive beyond 350 metres. It has a displacement of 4700 tons when on the surface and 5100 tons when submerged.

The submarine is powered by a pressurised water reactor producing 150 megawatts, helping it to exceed 25 knots.

It can be deployed for 70 days, and the endurance depends on onboard provisions.

The crew comprises 63 sailors and 15 personnel from the special forces.

Talking about weapons, the submarines are laden with F21 torpedoes, Exocet SM39 anti-ship missiles, land-attack naval cruise missiles, and naval mines.

The submarines can also undergo technological upgrades to install non-penetrating optronic masts to send high-resolution images to the combat information centre.

The class can also perform special missions through a removable dry-deck shelter to deploy dive teams and delivery vehicles.

Source: Maritime Shipping News