SS Richard Montgomery: Masts Removed to Mitigate Blast Risk

A long standing maritime hazard in the Thames Estuary has been partially neutralized as engineers complete the removal of three rusting masts from the SS Richard Montgomery.

The vessel, a United States ship built for the Allied war effort, ran aground on a sandbar off Sheerness in August 1944. It was carrying munitions intended to support operations following the D-Day landings. The ship broke apart during salvage attempts and sank with an estimated 1,500 tons of explosives in its cargo holds. For decades, the three masts remained visible above the waterline, serving as a familiar landmark for local residents and passing traffic.

Recent structural surveys indicated that the remaining superstructure was deteriorating, raising concerns that the masts could collapse onto the cargo. This scenario could potentially trigger a detonation. Nolan Conway, a naval architect with Resolve Marine Group, the firm hired for the task, noted that the vessel had begun to lean. He explained that the primary fear was that falling masts could strike the explosives, many of which are believed to have pressure fuses. An impact from such heavy objects could set off the cargo.

The engineering challenge required cutting the masts away without causing vibrations that might endanger the wreck or the workers. The team constructed a custom lifting frame to raise each mast vertically, ensuring they did not swing or sway during extraction. To minimize human risk, engineers employed a remotely operated underwater diamond wire saw. This device clamped around each mast with hydraulic arms and cut through the metal, eliminating the need for divers to enter the water.

U.K. maritime minister Keir Mather announced to the House of Commons that the complex project was finished ahead of schedule and within budget. The total cost for removing the three masts was just under $13 million. Mather stated that the masts had placed a significant load on the structure, and their removal reduces the risk of structural failure. This action supports the long term safe management of the site.

The explosives themselves have not been removed because the process would carry considerable risks. Experts remain divided on the potential consequences of a detonation. Conway described a range of possible outcomes, from effects on the shoreline to a tidal wave traveling up the Thames. At the lower end of the scale, the event might only close a nearby shipping channel. He summarized the uncertainty by noting that there is a large range of impacts, but none of them are really good. Despite this uncertainty, officials still judge the overall chance of an explosion to be low.

The government has maintained an exclusion zone around the wreck, which lies about 1.5 miles off the Sheerness coast. Mather confirmed that the site will continue to be subject to continuous monitoring and control through this zone. The masts themselves are expected to be preserved rather than scrapped. They have been moved to the Historic Dockyard Chatham museum, where they will be displayed in recognition of the ship's historic significance and its role in supporting Allied forces during the war. More than eight decades after it failed to reach Europe, the Montgomery and its cargo will stay where they came to rest, now entirely out of sight but far from forgotten.