The US Military Sealift Command operated 4 Victorious Class ocean surveilance ships that were all built to a twin hull SWATH design because of that hull form's greater stability at slow speeds. Two were stationed in the Atlantic Fleet during the 1990s. They were named Able and Effective. The Clyde based ship could have been one of these two. They were used to monitor the movement of submarines, using a variety of towed sonar systems.