Dealing with seabed bombs
With unexploded ordnance becoming an increasingly critical problem for seafarers and maritime developers, calls are growing to protect marine life from underwater blasts.
Anyone who has navigated Thames Estuary will be aware of a chilling landmark that lies eerily within its shallow shifting sands — the wreck of the SS Richard Montgomery.
In 1944, during World War II, the Richard Montgomery was carrying 7,000 tons of high-explosive munitions when it became grounded on the crest of a sandbank.
Intensive efforts were made to unload the lethal cargo, to be quickly abandoned when the hull cracked and the forward section began to flood.
Today, the wreck remains exactly where it sank 78 years ago — just 250 yards (228m) from the busy Medway Approach Channel, and worryingly close to nearby oil and gas facilities.
With its dark masts still clearly visible above the water, the wreck is now surrounded by a circle of conspicuous warning buoys marking out a strict 500m (1,640ft) exclusion zone.
Experts have calculated that if the wreck exploded it would send a 300m (980ft)-wide column of mud, metal and munitions 3,000m (9,800ft) up into the air and create a 4.5m (15ft) tsunami that would tear straight into heart of central London, causing widespread death and destruction. It would be the world’s biggest non-nuclear explosion.
A recent survey of the wreck has found new cracks in the hull and determined that the ship’s three masts could soon collapse onto the remaining stores of munitions.
A Royal Navy bomb disposal team has, therefore, been tasked to remove the masts, working with specialist contractor Briggs Marine, in a £4.6m two-month operation later this year.
Serious injuries
Decades of corrosion are also causing many thousands of unexploded underwater bombs to become more and more volatile, endangering those who work in the marine environment.
In 2020, the 15m (49ft) fishing vessel Galwad-Y-Mor was hauling pots in the North Sea off Norfolk when it disturbed a submerged 250kg (550lb) German-made wartime bomb.
The ensuing explosion threw Galwad-Y-Mor about so violently that its hull was ruptured and wheelhouse wrecked. Five of its seven crew suffered serious injuries.
A report into the incident by the UK’s Marine Accident Investigation Branch points out that unexploded ordnance is becoming increasingly volatile after years of being submersed.
In the event of encountering unexploded ordnance, seafarers are advised to follow these Maritime and Coastguard Agency (MCA) recommendations.
Low-order deflagration
For marine mammals, noise trauma can cause hearing loss and mass strandings.
In 2011, in Scotland, 39 long-finned pilot whales were beached following nearby munitions disposals, and in 2015 a study found that ordnance explosions in the North Sea caused permanent hearing loss in 1,280 harbour porpoises. Last year, 41 porpoises were found dead on German beaches following the clearance of mines in a protected marine area.
Pressure groups, such as StopSeaBlasts, are now advocating the use of an alternative method for dealing with unexploded underwater munitions — low-order deflagration. Used by the military since 2005, the technique uses a magnesium cone ignited against the munition, causing its explosive contents to ‘burn out’ from the inside. Tests reveal that low-order deflagration can be up to one hundred times quieter than conventional detonations.
“It’s crazy that we just blow up underwater ordinances,” argues actress and StopSeaBlasts activist Joanna Lumley. “Of course we need to find new ways of getting energy, such as offshore wind power, but it’s nuts that we’re allowing giant explosions to cause harm to precious whale and dolphin species when there is a viable alternative clearly available.”
International efforts
In Canada, divers are making progress in carefully recovering unexploded shells, for safe on-land detonation, from ships sunk by U-Boats in Conception Bay, Newfoundland.
“We have to take a lot of precautions when we’re doing it this way,” explains team leader, Adam Mullin, “and it involves some very fine motor-skill work. We have to pull the shells out of the ammo lockers, then stage them in a cargo net so we can lift them safely to the surface with a lift bag. They’re then transported to a demolition site to be safely blown up.”
German divers are also now recovering submerged munitions for on-land disposal.
“If we must detonate a bomb in the water, we will always set up an ‘air bubble curtain’ to protect any nearby marine mammals," explains Frank Ketelsen, head of diving operations at the Schleswig-Holstein bomb disposal unit in Kiel.
Dennis O’Neill is a freelance journalist specialising in maritime.