USS Blueback (SS-581)

Moored along Portland’s inner waterfront at OMSI, USS Blueback (SS-581) preserves the closing chapter of the U.S. Navy’s diesel-electric attack submarine era. Commissioned in 1959 as a Barbel-class boat and built by Ingalls Shipbuilding in Mississippi, Blueback represented a transitional design, incorporating lessons from streamlined postwar research while remaining conventionally powered. Her significance lies less in individual deployments than in what her career marked: she was the last non-nuclear submarine to enter U.S. Navy service and, upon decommissioning in 1990, the final conventionally powered combat-capable submarine withdrawn from the fleet. That status makes the hull a rare full-scale reference point for enthusiasts interested in the engineering and crew spaces of Cold War diesel boats, rather than their nuclear successors. Preserved in an urban setting rather than a naval base, Blueback anchors a different sort of context, set against civilian river traffic and city infrastructure, underscoring how rapidly such technology moved from front-line asset to historical artifact. The submarine’s survival as a museum piece allows close study of hull form, control arrangements, and the spatial compromises of a late-1950s attack submarine.