Sunken US cargo ship with 1,400 tons of explosives made safer after mast removal

A sunken U.S. warship, SS Richard Montgomery, long regarded as a ticking time bomb because it still houses approximately 1,400 tonnes of unexploded ammunition onboard, has been made slightly safer eight decades after it sank.

Engineers removed the ship’s three masts from the fragile wreck as experts feared they could collapse one day and potentially trigger an explosion.

“The vessel was starting to lean and deteriorate, so they could see some of the structures around the mast starting to collapse,” said Nolan, an architect with marine salvage firm Resolve Marine Group that carried out the mast removal operation last month.

Mast’s fall could trigger explosion

The mast had remained visible above the water near Sheerness, a coastal town about 50 miles (80 km) east of London on the Thames Estuary, since the ship sank in 1944.

The fear is the masts could have fallen onto the cargo itself, causing it to detonate,” he added.

Before the operation, his team completed extensive surveys to understand the wreck site using radar, magnetometers and sonar systems.

Special tools were then used to carry out the delicate operation, and extra caution was exercised to avoid any vibrations while approaching the wreckthat may set off the unexploded bombs still inside the wreck.

Divers carefully cut through the masts with a diamond wire, taking turns as they worked on the fragile deck. Although the masts remained well preserved, officials said the surrounding steel structure had become “paper thin.”

The exact munitions left onboard the ship, nicknamed Monty, are yet unknown. A defense agency report projected that more than 2000 cluster bombs, white phosphorus smoke artillery, and around 300 blockbuster bombs weighing nearly 2000 pounds (900 kg) were still on the ship.

The wreck continues to pose a potential hazard to nearby communities, although experts have divided views over how severe the consequences of an explosion would be.

A 2004 report suggested that the blast Some could cause a small tsunami, hurling debris nearly 1.8 miles (3 kilometers) into the air, “shatter almost every window in Sheerness” and devastate the town. However, David Alexander, an emergency planning expert at University College London, wrote in a 2019 paper that considerable uncertainty remains over the true level of risk posed by the wreck.

Masts preserved at Museum

Because of their historical significance, the detached masts have been transferred to the Dockyard Chatham, a maritime museum in Kent.

UK maritime minister Keir Mather welcomed the operation and said that the masts had put “significant load on the structure and their removal has reduced that risk and supports the long-term safe management of the site.”

Built in 1943 at Jacksonville, Florida, the World War II cargo ship was carrying about 7,000 tonnes of ammunition to Britain. It was due to anchor near Sheerness after passing through the Thames Estuary, but dragged its anchor and ran aground on a sandbank. Although the crew unloaded about half of the cargo, a crack in the hull ultimately caused the ship to sink, leaving thousands of tonnes of explosives on the seabed.

Besides removing the mast, the British government has long kept the area around the U.S. cargo ship as a shipping exclusion zone. Since last year, the government has also issued a no-fly zone for the area, and these restrictions will remain in force, the government said in a statement.

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