Navy to help dismantle masts of sunken ‘bomb ship’ in Thames

The Royal Navy has been called in to help a specialist firm cut the masts from a sunken cargo ship in the River Thames, after the latest survey revealed decay could trigger a deadly explosion of 1,400 tonnes of explosives on board. 

The SS Richard Montgomery was an American Liberty ship, which ran aground on the Nore sandbank in the Thames Estuary in August 1944, during World War II. Despite attempts to remove its dangerous cargo, the ship’s hull cracked and it sank off Medway, in Kent.

The Maritime and Coastguard Agency, which monitors the condition of the wreck and carries out regular surveys, had previously considered the risk of an explosion as remote. 

But the latest survey found the ship’s three masts were deteriorating and in a poor state. Reports have found cracks in the vessel’s hull are increasing, prompting fears that further decay to the wreck could trigger an explosion that would “throw a 300 metre-wide column of water and debris nearly 3,000 metres into the air and generate a wave 5 metres high”, according to a new report by the Ministry of Defence (MoD).

An explosion of all 1,400 tonnes of explosives on the SS Richard Montgomery could cause “mass damage and loss of life”, as well as causing damage to nearby oil and gas facilities in Sheerness, according to the MoD. 

Navy specialists trained in underwater demolitions have been called in to advise government sub-contractor Briggs Marine on safety as it dismantles the masts in a two-month operation.

The wreck has a circle of buoys around it, marking a 500-metre exclusion zone. The wreck is also under 24-hour radar surveillance by Medway Ports. Warning signs are attached to each of the three masts reading “Danger unexploded ammunition. Do not approach or board this wreck”.  

In a statement, the Maritime and Coastguard Agency said: “Ongoing monitoring and assessment of the SS Richard Montgomery has identified that the masts may be placing undue strain on the rest of the vessel structure. 

Left: A group of divers conducting a survey in 1981 pose with the warning signs on the masts of SS Richard Montgomery.

“In light of this, the decision has been made to seek to reduce the height of the masts in order to maintain the integrity of the hull and minimise the likelihood of structural collapse of the vessel. 

“This is part of the ongoing strategy to ensure that the risks posed by the vessel are suitably monitored, assessed and managed.”

The contract for the project is worth £4.6m, according to Bidstats. The masts are set to be removed by June 2022.