A Civil Engineering Feat

in Charlestown

(awaiting installation)

More than 700 feet long, Dry Dock #2 could accommodate the largest ships of the era. A vessel would enter when the dock was filled with water. Once it was secured in place and the caisson closed the entrance, the water was pumped out, giving men access to the hull to make all necessary repairs.

Photo by Walcott Cutler, courtesy of the Boston Public Library

This water-filled area in front of you was once the largest dry dock in the country. Completed in 1905, Dry Dock #2 was a key feature of the U.S. Navy’s modernization plan begun in the late 1800s. Hundreds of vessels were repaired or constructed here, often two or more at a time.

The Pump House behind you was an integral part of this engineering success. It served both Dry Dock 2 and Dry Dock 1 nearby, through a duct that ran under the dry dock 60 feet below ground. Its massive electrical pumps could fill Dry Dock #2 in one hour and drain it in two.

A hollow, steel barrier called a caisson—102 feet long, 36 feet deep—floated along Pier 3 when not in use. After a vessel entered the dry dock, the caisson was fitted into grooves at the entrance and pumped full of water so it would sink, closing the dry dock. The grooves and exterior water pressure kept the caisson in place so its water could then be pumped out.

Dry Dock #2 served ships until 1974 when the navy yard closed.

This 1932 photo shows Charlestown Navy Yard Dry Dock 1 empty and Dry Dock 2 with a vessel undergoing repairs.

US National Archives and Records Administration

USS Northampton in Dry Dock #2, 1930

Courtesy of Boston Public Library, Leslie Jones Collection

Outlets in the caisson would also be used to fill the dry dock when a ship was ready to leave. Behind the caisson waits the USS Maryland—the first ship to enter the dock.

August 1905 photo courtesy of the National Park Service

Sign Location

More …

Community activists. Colonial law. Political will. New state regulations. The combination created the 43-mile Boston Harborwalk–a public path, stretching from Logan Airport through seven neighborhoods to the Neponset River. In 1978, the Massachusetts Office of Coastal Zone Management (CZM) sought to improve public access to the waterfront. They succeeded by integrating early Colonial laws into new state regulations.

In the decades that followed, community activists, city and state government, and developers of shoreline projects have worked together to ensure the Harborwalk is always constructed along the waterfront. Some sites also provide public amenities–bathrooms, meeting places, kayak launches,
etc. The result is a fabulous path welcoming residents and visitors to our vibrant clean harbor.

Early Colonial laws established public right of access along tidelands to protect citizens’ rights to fish, hunt, and navigate at sea and along the shorefront. These laws go back even further: They stem from Roman law, which was incorporated into English law and brought over to Massachusetts by English
settlers. Then, in the 1640s, Massachusetts Bay Colony passed laws permitting private docks in the intertidal area (between low and high tide) as long as public access was retained. Almost all of Boston’s waterfront is filled land that was once the intertidal area. This, together with the centuries-old legal right of access, served as the underpinnings for the 1978 CZM regulations.

Resources

  • Carlson, Stephen P., Charlestown Navy Yard Historic Resource Study. Vol 1 – 3. Boston National Historical Park, 2010.
  • Charlestown Navy Yard. National Park Handbook. Produced by the Division of Publications National Park Service, 1995.
  • “Interesting Accessories to New Drydock at Charlestown Navy Yard,” Boston Globe, November 14, 1904.
  • “Drydock’s First Test Next Monday,” Boston Globe, March 25, 1905.
  • “Charlestown Drydock Now Ready for Formal Acceptance,” Boston Globe, July 26, 1905.
  • “USS Maryland  Floated Into New Drydock,” Boston Globe, August 12, 1905.
  • “Boston Serves the World’s Greatest Ships,” First National Bank of Boston Advertisement, Boston Globe, June 25, 1935.

Acknowledgments

Warm thanks for NPS historian Steven Carlson for his expertise.