This post has been updated to include additional information from the hearing.

CAPITOL HILL – The Navy will keep every one of its Arleigh Burke-class destroyers in service for 45 years, extending the life of the entire class. The move allows the Navy to reach a 355-ship fleet by 2036 or 2037, the deputy chief of naval operations for warfare systems said on Thursday.

The Navy currently has DDGs in multiple configurations – Flight I, Flight II and Flight IIA. Keeping each hull in the fleet for a 45-year service life equates to an extension of five to 10 years each, depending on the flight design.

Vice Adm. Bill Merz told lawmakers today every destroyer was already included in an Aegis modernization plan that would upgrade them each to Aegis Baseline 9 or 10 or Aegis BMD 5.4. The class-wide service life extension, as currently planned, does not include any combat system upgrades beyond what is already planned – though Merz said the Navy will be monitoring the threat set closely and retains the option to upgrade the combat systems later on.

“All of [those software variants] provide a ballistic missile defense capability, which is fundamentally the requirement we have to have,” he said in a House Armed Services seapower and projection forces subcommittee hearing.

“So whether that carries these through the life of the ship with the extension, we have time to work through that on what it will take, and the threat will get a big vote in how we do that.”

Merz told USNI News after the hearing that “this is an HM&E (hull, mechanical and electrical) extension, but every destroyer is already in the modernization pipeline, so every destroyer will be modernized. … The modernization they receive that’s already programmed may carry them through. Obviously, the threat’s going to get a vote on that, but one of the beauties is, instead of doing an individual ship-by-ship extension and extending the entire class, now we have the visibility to actually plan for that. We can pace it, plan it, fund it efficiently instead of one-and-done, one-and-done, one-and-done. We can be a lot more deliberate about how we handle this class. We’re big fans of this class of ship.”

Merz made clear, though, that this life extension would not absolve the Navy, Congress and industry of their task of finding an affordable way to ramp up shipbuilding. He told USNI News that this life extension gets the Navy to 355 ships in 2036 or 2037, but it’s the wrong mix of ships – the 355-ship goal is based on a particular blend of destroyers, attack submarines, aircraft carriers, amphibious ships and more, and the attack submarine fleet, in particular, will be well below the requirement in the 2030s. He said the Navy is “very focused on getting the right mix of ships in the end.”

Additionally, he said, if destroyer acquisition doesn’t pick up the pace – lawmakers are trying to get the Navy to move from two a year now to three a year – “you cannot use [the life extension] as a surrogate for building the new ones, or when those things tap out then we go off a cliff, and we’ll never get there.”

He added that the Navy, with this life extension plan, would hit 355 ships and hover there for a couple years but then would dip back down before eventually getting to a stable fleet size of greater than 355.

But, Merz made clear after the hearing, “that’s just with the DDGs. We have a lot of other levers that we continue (to study). Our commitment to the shipbuilding plan is aggressive growth profiles working with Congress, service life extensions – the DDGs were part of that – and then industry response. We still have a lot of ground to plow here to continue to accelerate this, and we’re excited about this.”

Merz praised the engineers at Naval Sea Systems Command for their great effort to ensure the class-wide extension could be done safely and cost-efficiently. He said the Navy was eyeing this effort when the budget and the 30-year shipbuilding plan was released in February, but the engineering wasn’t 100-percent complete and leadership decided it was better to surprise Congress and the public with good news later on versus have to backtrack on when they could actually reach a 355-ship fleet.

NAVSEA Commander Vice Adm. Tom Moore told USNI News in a December interview that his command had spent the past six months studying life extensions of several ship classes, with the DDGs garnering the most interest within the Navy and on Capitol Hill.

“Both the secretary of the Navy and the [chief of naval operations] are very interested in a program that would extend the service life of the DDGs in particular. It has great interest from the Hill as well. I think we’ve come through the technical hurdles and it’s just at this point, like everything else, it’s balancing everything else we want to get done in the budget,” Moore told USNI News at the time.

“It’s got to be part of our overall strategy to get to 355. It’s the only way you can get there – instead of getting there in 30 years, it’s the only way you can get there in say maybe 10 to 15 years. So I think that’s something we really want to go look at.”

Chief of Naval Operations Adm. John Richardson had said last summer while the technical work was still ongoing that extending the planned service life of the DDGs could help the Navy reach a 355-ship fleet 10 to 15 years faster than through new shipbuilding alone – and in fact, the DDG life extension plan bumps up the 355-ship mark from the 2050s to about 2036, a speed-up of at least 15 years.

Asked about the cost of this class-wide life extension plan, Merz told USNI News that “there’s no specific modernization or maintenance period that goes with that, so I don’t want to say they’re free, because you still have to man them and operate them, but unlike an individual ship where you’ve got to put it in the yard and you’ve got to do all these upgrades, we’re doing this based on the performance of the class. So all of them are just, from an engineering analysis, extended based on their past performance. If we have to modernize beyond that then we’ll have to learn how to pay for that.”

Additionally, with regards to the combat systems, the cost of the DDG modernization plan is already incorporated into Navy plans, but “if we want to do more than that, that will be an opportunity cost decision as we go forward – but the ships will be there to be able to do that. So now we have the option to have that discussion.”

In contrast to how the Navy is handling the class-wide extension of the Arleigh Burke destroyers, NAVSEA and Naval Reactors have made a very deliberate effort to pinpoint five Los Angeles-class attack submarines that could be extended past their intended service lives. Moore said during the hearing today that it is hard to keep submarines in service longer than their intended 35-year life due to the forces on the boat while submerging and the stringent requirements for the hull to remain certified to submerge.

However, he said, “in this particular case we had five additional cores available, and it presented us with an opportunity to get some SSNs accelerated back into the fleet. So between Naval Reactors and NAVSEA we went and looked, found some hulls that we could sharpen our pencils on and we were confident technically they could get to the service life that they’ve been asked to get to.”

Navy acquisition chief James Geurts said during the hearing that the Navy would begin work on the first submarine this year to prove the concept, and that the hull-by-hull SSN life extensions, along with the DDG class-wide life extension, shows “we are committed to 355 at least” for the future Navy fleet.