Last year, a French nuclear-powered submarine was badly destroyed by fire and was rescued from the scrapyard by chopping it in half and welding the salvageable half to a decommissioned submarine.
According to the French Defense Ministry, an intense 14-hour-long accidental fire on the attack submarine Perle while it was in dry dock for repairs last June rendered the front portion of the boat unusable. Steel parts were structurally damaged and could not be fixed.
During the fire at a shipyard in Toulon, southern France, the rear half of the 241-foot-long (73-meter) submarine, which has a displacement of 2,600 tons, was not affected.
Fortunately for the French navy, one of the Perle’s sister ships, the Saphir, had been withdrawn from service in 2019 and was being dismantled at a shipyard in Cherbourg, in the northwest.
The Saphir’s front section was structurally sound, so French officials decided it could be mated with the Perle’s rear section to create a single operational attack submarine.
In December, a semi-submersible ship transported the damaged Perle from Toulon to Cherbourg. According to a news release from French shipbuilder Naval Group, workers cut the Perle in half in February and the Saphir in half in March.
The back half of the Perle and the front half of the Saphir were placed on “walkers” at the Cherbourg shipyard at the beginning of this month so they could be carefully aligned and then welded together, according to a Naval Group statement. The joining work will be done in the coming months, according to Naval Group spokesperson Klara Nadaradjane.
The resulting submarine, still known as the Perle, would be about four-and-a-half feet (1.4 meters) longer than any of its predecessors to accommodate a “junction area” where miles of cables and pipes will be spliced together, according to the press release.
New living quarters will be built in the junction area, giving the crew of 70 submariners a little more room. Before being attempted onboard the submarine, all of this work will be practiced using a three-dimensional digital model, according to Naval Group. According to the study, the mission entails 100,000 hours of engineering research and 250,000 hours of industrial work by 300 people.
According to Nadaradjane, industry regulations prevent the company from providing a cost estimate for the operation. The Perle, commissioned in 1993, was the most recent of the French fleet’s six Rubis-class nuclear submarines. The Saphir, the class’s second boat, was launched in 1984 and served for 35 years before being decommissioned.
The new Barracuda nuclear-powered submarines, the first of which, the Suffren, was delivered to the French navy in November, would replace the Rubis-class submarines in the coming years. According to Naval Group, the sixth Barracuda sub isn’t expected to join the fleet until 2030, so the half-and-half Perle would be needed to maintain French attack submarine numbers at the required six.
The new Perle is scheduled to be transferred back to Toulon late this year for further technical work and enhancements to its battle systems before joining the French fleet in early 2023, according to Franck Ferrer, programs director for Naval Group’s Services Division.
“Carrying out this type of project in these circumstances, i.e. repair work that involves joining the fore and aft ends of two sister ships, is of course a first in the modern history of Naval Group,” Ferrer said.
But it’s not the first of its kind.
“The United States Navy did something similar to that when it replaced the bow of the damaged USS San Francisco, which ran aground on a seamount near Guam in 2005, with the bow of USS Honolulu, which was slated to be retired,” said Thomas Shugart, a retired US Navy attack submarine commander.
And, he said, these types of repairs are preferable to starting from scratch.
“For sure it would be a lot of work, but probably a lot less than building a whole new submarine,” said Shugart, now a fellow at the Center for a New American Security.
According to Shugart, new submarine design is exactly the same as what the French are doing in the Cherbourg shipyard right now.
“All new-construction US submarines are now built using modular construction, which is essentially putting pieces of submarine together, though clearly in a more planned-for fashion than in the case of this repaired French submarine,” he said.