Thames Shipwreck Masts Removed for Under $13 Million

Crews have finished removing the three masts from the SS Richard Montgomery, a World War II shipwreck resting in the Thames Estuary.

The Montgomery ran aground off Sheerness in August 1944 while carrying supplies for the Allied war effort. It broke apart during salvage and sank with an estimated 1,500 tons of explosives in its holds. For decades, the masts remained visible above the water. Recent surveys showed the structure was deteriorating, raising concerns that a collapse could strike the cargo.

Nolan Conway, a naval architect with Resolve Marine Group, described the primary risk. He stated that the ship had begun to lean. "The fear is the masts could have fallen onto the cargo itself, causing it to detonate," Conway said. He noted that some munitions likely have pressure fuses, meaning an impact could trigger an explosion.

The engineering team built a custom lifting frame to raise each mast without shaking the wreck. They used a remotely operated underwater diamond-wire saw to cut the structures free. This method allowed workers to avoid entering the water. U.K. maritime minister Keir Mather told the House of Commons this week that the project was completed ahead of schedule. The total cost was just under $13 million.

The cargo remains in place because removing it would carry high risks. Conway said experts disagree on the potential impact of a detonation. Estimates range from shoreline damage to a tidal wave moving up the Thames, or a minor event that closes a nearby shipping channel. "There's a large range of impacts, but none of them are really good," he said. Officials currently judge the chance of an explosion to be low.

The masts are now at the Historic Dockyard Chatham museum for display. The wreck remains in a government-mandated exclusion zone about 1.5 miles off the coast. Mather said the site will continue to be monitored through that zone.

The Montgomery and its cargo remain underwater near Sheerness, now entirely out of sight.