Gearhead News

April 15, 2021
Watch Two French Submarine Halves Get Grafted Together In A Remarkable Repair Job

There’s been a new twist in the project to graft a new front end to the fire-damaged French Navy nuclear-powered attack submarine Perle. Imagery from the dry dock shows that, rather than the expected “nose job,” two submarine halves are now being attached together to produce a “new” submarine, which will retain the Perle name. The procedure to fuse together the two hull halves of the Rubis class submarines will actually end up stretching the length of the submarine by 4 feet 6 inches. 

Earlier this month, the undamaged rear half of the Perle and the front half of the Saphir were carefully aligned on “walkers” at the Naval Group shipyard in Cherbourg, northern France. Saphir had previously been withdrawn from service in July 2019. Caused by faulty lighting, the fire onboard the Perle started on June 12 last year and burned for 14 hours, causing massive structural damage to the front end of the boat. There were no reports of injuries and no weapons or nuclear fuel were on board at the time.

BENOIT EMILE/MARINE NATIONALE/DÉFENSE
The fire-damaged front section of the Perle, while still in Toulon.

Work began on the repairs to the Perle five months ago, followed by the serious job of cutting this submarine in February and then the Saphir in March. Naval Group described the overall process as “hybridization” given the significant required changes in the area between the two hull halves, which will take more than 300 workers a total of 250,000 hours to complete. 

“Naval Group and its industrial partners are fully committed to enabling the French Navy to recover the potential of its six nuclear attack submarines as quickly as possible,” said Pierre-Eric Pommellet, Chairman and CEO of the Naval Group. “The success of the repair works on the Perle owes a lot to the know-how and professionalism of the Naval Group teams involved and we are proud to offer these unique skills at the service of a challenge whose scope we fully appreciate.”

Other repairs undertaken so far in the procedure to return the Perle to service has included welding work in the boat’s outer hull and rebuilding the inner decks in the new junction area — the new 4-foot 6-inch section that has been added to the middle. In addition, hundreds of cables and pipes have been attached together, along with the updating of some 2,000 drawings and documents, part of around 100,000 hours of engineering studies.

The design work around the area where the two halves will get joined together has also made use of 3D digital modeling of the submarine, creating a “digital twin,” an increasingly popular approach when working on repairs to older structures. In this way, a design team was able to plot exactly where different pipes and cables would run between the front and the rear sections, and work out where holes and supports were needed. Electricians and pipe-fitters were also able to use the digital twin to practice how they would do their work once aboard the real submarine.

The junction area itself will provide two new living quarters, making additional space for the crew, which numbers around 70.

WIKIMEDIA COMMONS
Crew aboard a French Navy Rubis class submarine.

The next steps for the Perle, once fully refurbished, will be the Periodic Interruption for Maintenance and Repair (PIMR), planned for the end of this year, after which the submarine will return to its base at Toulon, in southern France. The PMIR is roughly equivalent to the U.S. Navy’s Engineered Refueling Overhaul (ERO), during which the submarine is refueled and upgraded for returning to sea. The submarine is expected to be on active duty with the French Navy again in early 2023.

Jean-Michel Roche/Wikimedia Commons
The submarine Saphir, which served as the donor for the new front hull section for the Perle.

French Minister of Defense Florence Parly announced last October 22 that the Perle would be repaired and returned to service, specifically to help address the shortage of nuclear attack submarines. Although the six Rubis class submarines are scheduled for replacement by the new Barracuda class, Perle is the youngest, entering service in 1993, and the repair work was judged worthwhile, although the exact costs involved are unclear. In the meantime, the first of the Barracudas, the Suffren, was delivered to the French Navy last November.

Resurrecting a damaged nuclear-powered submarine is not without precedent, of course. The U.S. Navy returned the Los Angeles class attack boat USS San Francisco to service after its collision with an underwater seamount in the central Pacific in 2005. In that case, the submarine received the bow of the USS Honolulu, another Los Angeles class boat, process that you can read more about here

U.S. Navy
The Los Angeles class attack submarine USS San Francisco (SSN-711) in dry dock to assess damage sustained after running aground approximately 350 miles south of Guam in January 2005.

Another U.S. Navy submarine was less fortunate. The Los Angeles class attack boat USS Miami
catching fire in its dry dock during an overhaul in 2012. The submarine was retired from service as result.

U.S. Navy
USS Miami enters dry dock at the Portsmouth Naval Shipyard in March 2012, just two months before being seriously damaged in a fire.

Since then, major fires have also broken out aboard other U.S. Navy vessels, including the amphibious assault ship USS Bonhomme Richard, the future USS John F. Kennedy, a Ford-class aircraft carrier, and on Bonhomme Richard’s sister ship, USS Kearsarge. Other shipboard fires have blighted the U.S. Coast Guard, as well. The damage to Bonhomme Richard was so significant that the Navy decided to scrap it, a process that will itself cost an estimated $30 million.

Clearly, significant efforts are going into returning the Perle to service, with the Naval Group conducting unique work in parallel to the construction of five Barracuda successor boats in the same yard. It points to the great value that the French Navy places on its attack submarines, which conduct critical missions including providing defensive screens for the aircraft carrier Charles de Gaulle and the Triomphant class nuclear-powered ballistic missile submarines. After all, a class of six boats provides for two or three that be deployed at sea at any given time. What is more, their areas of operations are expanding, too, including a rare trip to the Pacific by the Rubis class boat Émeraude at the end of last year.

U.S. Navy
The Los Angeles class attack submarine USS Asheville (foreground) trains with the Émeraude in the Pacific last December.

By the time the last of the Rubis boats are retired from service in around 2030, this class will have provided close to a quarter of a century of service to the French Navy. Along the way, the return to service of the Perle will no doubt stand out among the most remarkable episodes in their long careers.

Contact the author: thomas@thedrive.com

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