South Boston Naval Annex

South Boston Naval Annex
South Boston, Massachusetts
The Annex, circa 1958. In this image, South is on top.
Type	Shipyard annex
Site information
Controlled by	United States Navy
Site history
Built	1920
In use	1920–1974

The South Boston Naval Annex, was a 167-acre (68 ha) United States Navy shipyard annex located in South Boston. It was the annex of the Boston Navy Yard, and was operational from the 1920 to 1974, when it was closed along with the main shipyard. The annex is also home to Dry Dock Number 3, the one of the largest dry docks on the East Coast.

The Department of Defense purchased a large part of the Commonwealth Flats in 1920, and split up the land between the Naval Annex and the South Boston Army Base. At this time, the Navy began construction of buildings, which would continue up until World War II. Rail service to the annex was provided by Track 61.

At the South Boston Annex, work was started in March 1940 on a quay wall and wharf and on a machine shop 1,300 feet (400 m) long and 500 feet (150 m) wide. The following spring a new power plant project was undertaken, to provide six boilers, a compressor and a primary connection to the Edison system. An additional waterfront project, comprising two 980-foot (300 m) timber piers and a steel sheet pile bulkhead, was started in the summer of 1941, followed in September by construction of an additional shop 420 feet (130 m) long and 120 feet (37 m) wide.

In December 1941, work was started on a graving dock, 693 feet (211 m) long, 91 feet (28 m) wide at the entrance, and 32 feet (9.8 m) deep over the blocks, for the repair of cruisers. This dock, which was built inside a cellular steel pile cofferdam, was completed and placed in service in March 1943. The cofferdam was later incorporated as part of Piers 5 and 6.

Work was also undertaken in 1941 on a 500-man barracks for ship's crews, necessitated by the fact that with three-shift repair work, the crews could not be quartered aboard.

The expansion of the Annex continued with the construction of an additional 900-foot (270 m) pier, started in the fall of 1942, a rigger's shop, a paint shop, and a general shop, started in November of that year, and extensive improvements and additions to utilities, streets, tracks, and equipment.