In late February and early March 2020, the Museum cleaned out the 11-foot-long bores in both of USS Monitor‘s Dahlgren guns using a custom-made machine. This massive undertaking took years of precise planning.

Monitor’s guns are the largest guns to ever be bored, giving this significant conservation step its own mark in history. The removal of the marine material was the final mechanical cleaning step before the guns can be dried and put on display.

In 2002, after the National Oceanic and Atmospheric Administration (NOAA) and U.S. Navy divers raised the 120-ton USS Monitor turret, the massive artifact came to The Mariners’ Museum and Park for conservation, curation, and display. The turret was covered in thick layers of concretion and over time, the material was removed using hand and pneumatic tools exposing the turret itself and hundreds of additional artifacts including the two 11-inch (bore diameter) Dahlgren guns.

In 2004, the guns were removed from the turret and transferred to independent treatment tanks to advance the removal of concretion and facilitate the extraction of marine salts using electrochemical treatments.

By 2018, the exterior of the guns had been cleaned of ocean deposits, but the bores of the gun are still full of marine materials which cannot be accessed by hand tools. To remove this material, a custom boring machine and holding apparatus was made by the Museum and Master Machine and Tool of Newport News.

The Museum team is thrilled to have accomplished such an impressive milestone in the conservation treatment of USS Monitor‘s Dahlgren guns. We are grateful to all of our partners and supporters who helped make this happen!