Thames Wreck Masts Lifted to Museum, 1,500 Tons of Munitions Remain

Crews have removed the three rusting masts from the SS Richard Montgomery, a World War II shipwreck resting in the Thames Estuary. The operation concluded ahead of schedule, according to U.K. maritime minister Keir Mather, who confirmed the work was finished this week. The masts have been transported to the Historic Dockyard Chatham museum for display. The ship’s cargo of explosives remains on the seabed.

The Montgomery ran aground in August 1944, about 40 miles from London. It was one of 2,700 vessels built in the United States to support Allied operations after D-Day. The ship broke apart during salvage attempts and sank with an estimated 1,500 tons of munitions in its holds. For decades, the masts protruding from the water served as a visual marker for the site.

Recent surveys indicated the structure was deteriorating. Officials feared the masts might collapse and strike the cargo, triggering a detonation. Nolan Conway, a naval architect with Resolve Marine Group, explained that some munitions are believed to have pressure fuses. An impact could potentially set them off, making the removal process delicate.

The engineering team faced the challenge of cutting the masts without shaking the wreck. They built a custom lifting frame to raise each mast without swinging. To cut the masts underwater, they used a remotely operated diamond-wire saw. This tool clamps around the mast with hydraulic arms and passes the saw through, eliminating the need for divers in the water.

The project cost just under $13 million, according to The Guardian. Mather stated in the House of Commons that the masts had placed a significant load on the structure. Removing them reduces that risk and supports long-term management of the site. The government maintains an exclusion zone about 1.5 miles off the Sheerness coast to control access.

Experts continue to monitor the site closely. Conway noted that estimates for a potential explosion vary widely. Predictions range from shoreline damage to a tidal wave traveling up the Thames, or a minor event closing a nearby shipping channel. He described the potential impacts as a large range of outcomes, none of which are ideal. Officials still judge the overall chance of an explosion to be low.

The masts will be preserved at the museum to recognize the ship’s historic role. The Montgomery and its cargo remain where they came to rest, now entirely out of sight but subject to continuous control through the exclusion zone.