South Boston Naval Annex

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

Opening
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.

World War II
At the South Boston Annex, work was started in March 1940 on a quay wall and wharf and on a machine shop 1300 ft long and 500 ft 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 ft timber piers and a steel sheet pile bulkhead, was started in the sumer of 1941, followed in September by construction of an additional shop 420 ft long and 120 ft wide.

In December 1941, work was started on a graving dock, 693 ft long, 91 ft wide at the entrance, and 32 ft 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 ft 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.

Post-War to closure
After the war, the yard was used to store ships that were placed in reserve. In 1974, the Boston Navy Yard was closed, and the yard became the Boston Marine Industrial Park after the City of Boston purchased the land.

Present day
Today, the former yard is home to the various companies which have moved in over the years, having been integrated into the larger South Boston Waterfront. Sail Boston has also used the land to host ships when they are in port as well, along with the South Boston Army Base's land, which now operates as the Black Falcon Cruise Terminal. Many of the buildings and cranes still stand, with their numbers being maintained. Dry Dock Number 3 is also being actively used by a company to repair ships.