Dry Dock 1: The Granite Basin That Has Repaired USS Constitution Since 1833

USS Scorpion in Dry Dock 1, August 1900. Boston National Historical Park, BOSTS 14208-1.

Before dry docks: careening

In the Age of Sail, a navy yard could get by without a dry dock. Most repairs needed only a pier and a simple crane. Small vessels could be hauled out of the water; larger ships were careened — worked with ropes and the tides onto a beach, left high and dry and tipped on one side, so workers could clean and repair one half of the hull at a time.

The Swedish ship Vera careened for hull work. Boston National Historical Park, BOSTS-14543.

Careening was clumsy and slow but cheap, and the small early U.S. Navy lived with it — though Britain and France had built dry docks more than 250 years earlier. The fleet's growth during the War of 1812 changed that: a larger navy could not wait on the tides.

Granite bathtubs

A dry dock is simple in concept: a basin open to the water. Flood it, float a ship in, seal it, pump it dry, and the ship settles onto keel blocks.

How the dock works: fill the basin, float the caisson out and the ship in, sink the caisson and pump the water out. NPS illustration.

Making a watertight space big enough for a ship was hard. In 1827 the Navy ordered two dry docks, one at Norfolk, Virginia, and one at Boston, both designed by civil engineer Loammi Baldwin Jr. and built of granite from Quincy, Massachusetts. Baldwin's system was advanced for its day: steam engines drove the pumps. The mouth was closed by a caisson — a floating gate built like a ship's hull, sized to fit the entrance.

Dry Dock 1's caisson, first of wood; a steel one was launched in 1901. Naval History and Heritage Command, NH 2136.

The docks were built when the Navy's largest ships were wooden sailing vessels like USS Independence and USS Delaware. At under 200 feet, Delaware fit easily into Norfolk's 341-foot dock and became the first ship repaired in either. Boston's opened weeks later, and on June 24, 1833, USS Constitution became the first ship repaired in Dry Dock 1.

Growing with the ships

For twenty years the small Navy used the dock only now and then, and commercial ships kept it busy. But as ships grew, the dock had to grow too.

• 1858: workers numbered every granite block, dug 65 feet further inland, loosened the masonry with small powder charges, and moved the head of the dock back block by block in the same order, filling the gap with new stone from Cape Ann. The dock was 20% larger, enough for the ships of the Civil War era.
• 1905: battleships had outgrown it, so the far larger Dry Dock 2 was completed. Destroyers and submarines still fit Dry Dock 1, which was busy in both world wars fitting out new ships and repairing damaged ones.

Dry Dock 1 during its 1947 seaward extension. Boston National Historical Park, BOSTS 8796-270.

• 1947: a temporary cofferdam held back the harbor while a concrete extension was laid seaward for longer escort ships. The dock has measured 404 feet ever since.

The 1947 cofferdam that let workers build the extension in the dry. Boston National Historical Park, BOSTS 8796-1367.

Through the 1950s and 60s, destroyers such as USS Cassin Young (DD-793) came in for maintenance and Cold War refits, served by the sonar repair shop in nearby Building 10 until it moved in 1958.

Still working

When the yard closed in 1974, Dry Dock 1 stayed in service. Since Cassin Young joined Boston National Historical Park in 1978, the nearly 200-year-old dock has maintained both museum ships — the wooden-hulled Constitution and the steel-hulled destroyer. Neither could be preserved without it.

Sources

Based on "Charlestown Navy Yard: Dry Dock 1," Boston National Historical Park, National Park Service; a work of the United States government in the public domain. It draws on the park's historic resource study (Carlson, 2010), its histories of the yard (Bearss and Black, 1993; Black, 1988) and the 1980 Historic Structure Report on Dry Dock 1. The source spells Cape Ann "Cape Anne".