PENTAGON — The Navy will beef up the weapons, armor and sensors on its two existing classes of Littoral Combat Ships (LCS) in an answer to Secretary of Defense Chuck Hagel’s call for a tougher Small Surface Combatant (SSC), the Navy announced in a late Thursday briefing with reporters.

The two variants of the ship will replace the last 20 ships in the initial plan for 52 Flight 0 Lockheed Martin Freedom-class and Austal USA Independence-class LCS hulls as part of the SSC directive the Office of the Secretary of Defense (OSD) outlined to the Navy in a January memo.

“By avoiding a new class of ships and new system design costs, it also represents the most responsible use of our industrial base investment while expanding commonality in the fleet,” Hagel said in a statement following the decision.

The Navy reviewed 18 existing ship designs in addition to a plethora of permutations of the existing LCS hulls before deciding on the two designs, Sean Stackley, Assistant Secretary of the Navy for Research, Development & Acquisition (RDA) told reporters.

The two hulls will feature an unspecified 3D radar upgrade, an over-the-horizon surface to surface anti-ship missile, include a multifunction towed array sonar and displace less than the Flight 0 variants, according to information from the service.

The Freedom and Independence variants were designed to be modular hulls and conform to different task by swapping out different mission packages — mine counter measures (MCM), surface warfare (SuW) and anti-submarine warfare (ASW).

The new SSCs will keep an element of modularity focused on the ASW and the SuW mission packages, with the ASW SSC package adding the variable depth sonar of from the existing ASW package.

Absent from the new concept is a significant air defense capability in the form of vertical launch system capable of carrying the Navy’s family of Standard Missiles but Stackley said the SSC would be able to operate independently.

“We have given this multi-mission ship the degree of self defense that it needs so it does not have to be operating beneath the umbrella of a major ship,” Stackley said.

“Each ship has its own threat set it has to be designed against and what this does is this expand the threat set of Small Surface Combatants for operations.”

The concept also increases the level of survivability of the SSC by adding armor to critical spaces onboard and hardening some systems. Survivability of both LCS variants in combat has been a constant criticism of the original LCS design.

“To call it Navy standard, it matches what we would have for a frigate,” Stackley said.

The ships will also improve on the electronic warfare (EW) capability with a so-called “lite” version of the Navy’s Surface Electronic Warfare Improvement Program (SEWIP), said Chief of Naval Operations (CNO) Adm. Jonathan Greenert to reporters.

The new ships will cost about $60 to 75 million more than the current versions of LCS, Stackley said.

Over the life of each class, both have come in at less than $500 million a hull, not including the mission packages.

Moving forward the Navy is to provide an acquisition strategy to OSD by May in order for the service to begin buying the ships in Fiscal Year 2019 as well as an analysis if the SSC additions can be installed in older LCS hulls.

In February, Hagel announced the decision to cap the Flight 0 LCS variants at 32 hulls and directed the Navy to “submit alternative proposals to procure a capable and lethal small surface combatant, consistent with the capabilities of a frigate,” he said at the time.

“I am concerned that the Navy is relying too heavily on the LCS to achieve its long-term goals for ship numbers. Therefore, no new contract negotiations beyond 32 ships will go forward. With this decision, the LCS line will continue beyond our five-year budget plan with no interruptions.”