Thames Wreck Now Fully Submerged After Mast Removal

Crews finished removing the three rusting masts from the SS Richard Montgomery on Thursday, completing a delicate engineering project aimed at preventing a potential explosion in the Thames Estuary. The U.S. ship, which sank in 1944 with 1,500 tons of ammunition in its holds, no longer breaks the water’s surface, though the munitions remain untouched beneath the waves.

The vessel ran aground on a sandbar off Sheerness, roughly 40 miles from London, while carrying supplies for Allied forces after the D-Day landings. It broke apart during early salvage attempts and settled into the riverbed. For decades, its masts served as a visible marker for local residents and ships, but recent surveys indicated the structure was deteriorating. Officials worried the masts might collapse and strike the cargo, triggering a detonation.

Nolan Conway, a naval architect with Resolve Marine Group, explained that the ship had begun to lean, increasing the risk that the masts could fall onto the explosives. He noted that some of the munitions are believed to have pressure fuses, meaning an impact could set them off. To avoid shaking the wreck or putting workers in harm’s way, his team built a custom lifting frame to raise each mast steadily. They also used a remotely operated underwater diamond-wire saw to cut the masts free, eliminating the need for divers.

U.K. maritime minister Keir Mather announced in the House of Commons that the project finished ahead of schedule and on budget. The total cost was just under $13 million. Mather stated that the masts had placed a significant load on the structure, and their removal reduces that risk while supporting long-term safety management. The government has maintained an exclusion zone around the wreck, which sits 1.5 miles off the Sheerness coast, and Mather confirmed that continuous monitoring will continue through that zone.

Experts continue to debate the potential consequences if the remaining explosives were to detonate. Conway said estimates vary widely, ranging from minor shoreline damage to a tidal wave moving up the Thames, or a relatively small event that might only close a nearby shipping channel. He described the range of impacts as broad, though none are favorable. Officials still assess the overall chance of an explosion as low.

The removed masts are not being scrapped. Mather said they have been transferred to the Historic Dockyard Chatham museum for display. The artifacts will recognize the ship’s role in supporting Allied forces during World War II. The Montgomery and its cargo will remain submerged, now entirely out of sight but still subject to strict oversight.