Too Heavy: Engineers are addressing a design flaw with the Isaac Peral, lead ship of Spanish builder Navantia's new class of subs, that made it so heavy it would be unable to resurface if it submerges. (Navantia)
ROME — US-based Electric Boat has signed on to work with Spanish shipbuilder Navantia to devise a fix for the company’s overweight S-80 submarine, the Spanish Defence Ministry said, after engineers discovered the sub is so heavy it could not resurface if submerged.
But as work proceeds urgently to identify the precise nature of the problem and slim down the sub, one analyst said weight is not the only issue. The air-independent propulsion (AIP) system onboard also is underperforming, he said.
“It was meant to allow the submarine to stay underway for 28 days but only manages one week,” said Rafael Bardaji, head of the Madrid-based Strategic Studies Group, a private think tank. “This is the main advantage of the submarine, and it does not work.”
A spokeswoman at Navantia declined to comment on the performance of the AIP system.
An engineering error caused the submarine to be 75 tons overweight, making it unable to resurface if it submerged, a Spanish industrial source said.
To tackle the weight problem, Electric Boat — owned by General Dynamics — was brought in by Navantia to help nail down the problems and find a solution.
EB, long the lead design shipyard for US submarines, is familiar with the S-80 program through a foreign military sales contract from the US Navy in support of the Spanish Defense Ministry. It also provided extensive assistance to BAE Systems a decade ago during construction and design problems with Britain’s Astute-class nuclear submarines.
The S-80 problems emerged as the hull of the first submarine, Isaac Peral, was nearly complete at the company’s shipyard in Cartagena. Only one section was left to be joined and a launch was planned before the end of the year.
“One solution to the weight problem could be to add length to the submarine, while another option that could be studied is to complete the first submarine without installing the AIP system,” the industrial source said.
“The firm is working with Electric Boat and while nothing has been decided, a conclusion should be reached in mid-July,” the source added.
A spokesman for Electric Boat declined to comment on the Navantia situation, but the US Navy confirmed that submarine building officials and EB are assisting the Spanish company.
In a statement issued May 7, Navantia announced that the sub had strayed from its planned weight, but stated that “delays are common in these projects.” The S-80 was likely to encounter challenges given the advanced technologies onboard, the statement said.
Navantia said the delivery date would slip by one to two years while it decided on a fix and made changes.
Work, meanwhile, has been halted on the €1.8 billion (US $2.3 billion) program to build the submarines, which are 71 meters long with a submerged displacement of 2,430 tons. With a maximum submerged speed of 19 knots, the submarines are designed to carry 32 crew members and eight special operations forces personnel. Spain has ordered four submarines of the type, and all are in various stages of production.
Bardaji said the weight problem is based on a simple error that was not corrected as work advanced.
“I have been told it was a simple matter of someone writing in one zero when they should have written three,” he said. “The idea is now to extend by 3 to 4 meters the main hull of the vessel.”
Navantia has not estimated the cost of reducing the submarine’s weight, but Bardaji said it would not be a cheap fix.
“The buoyancy problem alone could cost up to half a billion euros to cover redesign and extra construction, without considering the propulsion problem,” said Bardaji, a former director of Spain’s Office of Strategic Assessment.
As to the rest of Spain’s fleet, of the three remaining submarines of the Agosta type, two have been laid up for lack of funds while a third is being refitted to allow it to run until 2018, said Pat Bright, a US-based analyst with AMI International.
“The ministry has put a request to parliament asking for €30 million in funding to extend the life for two to three years of the submarine left in service, which will need ample funds for upkeep because of its age,” he said. “The idea of a submarine loaned from Germany has also been suggested.”
In its statement, Navantia said that the S-80 program is a “key element” in Spain’s national defense, based on a national design, granting “industrial independence” while putting the company “in a competitive position in the export market.”
“Navantia is stating that all advanced programs face such problems, but this will impact their credibility,” Bardaji said.
A second expert was more inclined to agree with Navantia.
“This is the first submarine designed by Navantia, so these kind of problems are normal,” said Enrique Navarro Gil, a Spanish defense analyst. “HDW [of Germany] had similar problems in the past. Don’t forget that it is less than 3 percent of total weight. If Navantia solves this issue properly, it will demonstrate a huge engineering capacity.
“Obviously, it is not good news, but I do not believe it will affect potential sales if Navantia can solve the issue quickly, although if the problems are not solved, the credibility of the company will be damaged,” Gil said. “It is possible that cuts among experienced engineers recently — all those older than 52 were retired — has made it difficult for the company to face up to these technological issues.”
The submarine construction problems come at a desperate time for the Spanish Navy, which has been decommissioning ships due to lack of operating funds. The aircraft carrier Principe de Asturias was decommissioned in February and is for sale.
“They’re in a bad situation right now,” Bright said. “Procurement budgets are down, the operational force is significantly reduced, ships are laid up.”
Christopher P. Cavas in Washington contributed to this report.