Thames Wreck SS Richard Montgomery Loses Masts but Keeps Bombs

Three rusting masts no longer jut out of the water near Sheerness. Their removal marks the end of a delicate engineering project aimed at preventing a potential disaster on the River Thames. The structure was the SS Richard Montgomery, a U.S. ship that went down during World War II. It still sits on the sea floor with a vast quantity of explosives intact. Officials confirmed the job is finished. The munitions themselves were not touched. Experts say they will continue to monitor the site closely.

The Montgomery was one of roughly 2,700 vessels built in the United States to support the Allied war effort. It ran aground on a sandbar in the Thames Estuary in August 1944. The location is about 40 miles from London. The ship was carrying munitions intended for use after the D-Day landings. It broke apart during salvage attempts and sank. Its cargo holds contained an estimated 1,500 tons of explosives. For decades, the three masts were a familiar sight to locals and passing ships.

Recent surveys showed the structure was deteriorating. There were fears the masts could collapse. A collapse could have set off an explosion. Nolan Conway is a naval architect with Resolve Marine Group. The firm was hired to remove the masts. Conway said the vessel had begun to lean. He explained that the fear was the masts could fall onto the cargo and cause it to detonate. He noted that some munitions are believed to have pressure fuses. An impact could potentially set them off.

The main challenge was cutting the masts without shaking the wreck. Workers had to be kept safe. Conway’s team built a custom lifting frame. It raised each mast clear without swinging or swaying. They also used a remotely operated underwater diamond-wire saw. The device clamps around a mast with hydraulic arms. It passes the saw through the structure. This meant no divers had to enter the water.

U.K. maritime minister Keir Mather spoke to the House of Commons this week. He stated that the complex project was completed ahead of schedule and on budget. The cost to remove all three masts was just under $13 million. Mather said the masts had put significant load on the structure. Removing them reduces that risk. It supports the long-term safe management of the site. The explosives remain in place because removing them would carry considerable risks.

Experts disagree about what a detonation would do. Conway said estimates range widely. Some predict effects on the shoreline. Others suggest a tidal wave traveling up the Thames. Still others think it would be a fairly minor event. That scenario might only close a nearby shipping channel. Conway noted there is a large range of impacts. He added that none of them are really good. Officials still judge the overall chance of an explosion to be low.

The government has long kept an exclusion zone around the wreck. It lies about 1.5 miles off the Sheerness coast. Mather said the site will continue to be subject to continuous monitoring. Control through that zone will remain in place. The masts are expected to be preserved. Mather said they have been moved to the Historic Dockyard Chatham museum. They will be displayed in recognition of the ship's historic significance. The ship played a key role in supporting Allied forces during the war.

More than eight decades have passed since the Montgomery failed to reach Europe. The ship and its cargo will stay where they came to rest. The site is now entirely out of sight. Yet it is far from forgotten. The removal of the masts changes the visual landscape of the Thames Estuary. It also shifts the focus to the long-term management of the hidden explosives beneath the water.