United States Navy reserve fleets
The United States Navy maintains a number of its ships as part of a reserve fleet, often called the "Mothball Fleet". While the details of the maintenance activity have changed several times, the basics are constant: keep the ships afloat and sufficiently working as to be reactivated quickly in an emergency.
Mothballed ships in Suisun Bay, California (2010). The battleship USS Iowa at the right-side end of the group has since become a restored museum ship in San Pedro, Los Angeles.
View of the reserve fleet laid up at Naval Station San Diego, circa in the 1950s
Ships in the US Reserve Fleet at Suisun Bay in 1972
Aerial view of the US Reserve Fleet at Suisun Bay in 1995
A reserve fleet is a collection of naval vessels of all types that are fully equipped for service but are not currently needed; they are partially or fully decommissioned. A reserve fleet is informally said to be "in mothballs" or "mothballed". In earlier times, especially in British usage, the ships were said to be "laid up in ordinary".
HMS Vanguard in about 1947, when it was part of the British Reserve Fleet
Ships of the U.S. Navy's Reserve Fleet in the Reserve Basin at the Philadelphia Naval Shipyard, 1956
HMS Unicorn in ordinary
