 The first moored training ship was a fleet ballistic missile submarine, redesignated as (MTS-635) in 1989, followed a year later by , a ballistic missile submarine, redesignated as (MTS-626).Conversion of these two boats took place at the Charleston Naval Shipyard and modifications included special mooring arrangements with a mechanism to absorb power generated by the main propulsion shaft.The Navy plans to add two more moored training ships to this facility,  and , a pair of attack submarines.