If any reader is a boating enthusiast and owns a boat, they will know that there are some places where it’s dangerous to sail. One of them is the Thames Estuary, near the town of Sheerness. There’s a sandbank called the Nore that has quite a bad reputation, as we’ll see. But what’s really concerning isn’t the location, but the fact that, half-submerged above the surface, lie the remains of the SS Richard Montgomery, a ship full of explosives.

It’s not uncommon for shipwrecks to keep the cargo they were carrying at the time of the wreck. Some cargo gets salvaged, especially if it’s valuable, like coins and bullion, but most of it stays at the bottom, along with the crew, in these makeshift underwater cemeteries. This can pose a certain danger because sometimes the nature of the cargo is hazardous, like mercury or radioactive waste. However, there’s at least one case where the risk is much more direct, and the aforementioned ship is a good example.

The Nore Sandbank marks the point where the Thames meets the North Sea. As we mentioned before, it’s a place of ill repute due to its natural dangers, which, in 1732, required the permanent anchoring of the first known lightship. However, its negative associations came a bit later, in May 1797, when the crews of several Royal Navy ships, which often gathered there, mutinied due to their poor living conditions and delays in pay. The ringleaders were executed, but the Admiralty took note of their grievances and tried to address them.

Location of the wreck and proposed locations for the new London airport.
Location of the wreck and proposed locations for the new London airport. Credit: Ordinance Survey / Wikimedia Commons

Throughout the following centuries, it was clear that the river’s estuary was a delicate place that needed protection, which is why fortifications were built around it, and during World War II, coastal and anti-aircraft batteries were installed. During that last conflict, the SS Richard Montgomery incident occurred when it was waiting for the arrival of a convoy to which it was supposed to join in order to cross the English Channel toward the Normandy beaches, where the famous D-Day had taken place the previous month.

The ship was the seventh of a series of 82 similar units built at the St. Johns River Shipbuilding Company shipyards, an American company specializing in Liberty-class merchant vessels. These were armed cargo ships that the US conceived to send to Great Britain under the Lend-Lease Act (which provided food, oil, and military equipment, first to the British and later to other allies) to compensate for the losses that German submarines were causing to the British fleet.

It was named after an Irish general who died during the assault on Quebec led by Benedict Arnold during the American Revolution, and was launched on June 15, 1943, with completion on July 29. It measured 128.88 meters in length, 17.37 meters in beam, and 8.48 meters in draft, with two propellers allowing it to reach a speed of 11 knots, displacing a total of 14,474 tons. After several successful voyages during that war, in August 1944, it set sail from the port of Hog Island (at the mouth of the Delaware River, Philadelphia) bound for England, under the command of Captain Wilkie.

It was carrying 6,127 tons of explosives that were to be delivered to the artillery and engineering sections of allied troops stationed in Europe to supply them in their European campaign. Specifically, its final destination was the port of Cherbourg, to which it was supposed to reach after joining a convoy at the Thames Estuary. When it arrived at the designated point, the harbourmaster ordered it to anchor at a usual spot known as Great Nore Anchorage, in the northern part of Sheerness, Kent.

Then disaster struck. It was August 20 when it attempted to anchor, but the anchor didn’t hold in the sandy bottom, and the SS Richard Montgomery began to drift dangerously toward the sandbank while the other ships also waiting for the convoy in the vicinity tried to warn it by sounding their horns. However, nobody on board could interpret these signals, and to make matters worse, the captain was asleep in his cabin; inexplicably, nobody went to wake him.

Ship condition in 2012, according to Maritime & Coastguard Agency report.
Ship condition in 2012, according to Maritime & Coastguard Agency report. Credit: MCA

Soon after, the ship ran aground 250 meters from the mouth of the Medway, a small river that also ends in the Thames Estuary, between the islands of Sheppey and Grain. The depth at that point was 7.3 meters, one meter less than the SS Richard Montgomery’s draft, which, in addition to having full holds, had increased its draft by another meter. A later investigation cleared the captain of fault and placed the blame on the harbourmaster, but in the meantime, the wreck left an actual mega-bomb just 2.5 kilometers from Sheerness.

The risk for a stranded ship is that the waves can break its hull in a short amount of time, which is why a rescue team was quickly organized; not to salvage the SS Richard Montgomery, which was considered lost, but to rescue its dangerous cargo. The work was undertaken by dockworkers from Rochester, who started just three days later, but on the 24th, what they feared happened: the hull cracked, and several forward holds were flooded.

The operation continued frantically, but on September 25, it became impossible to continue, and all personnel abandoned the ship, which later ended up splitting in half. Much of the cargo was salvaged, but not all of it; there were still 1,400 tons of explosives on board, including TNT, bombs of various types and weights, cluster and fragmentation bombs, phosphorus bombs, detonators, smoke bombs, signaling pyrotechnics, and more.

That the whole thing faded into the background in a wartime context where the focus was on preventing the fall of Hitler’s self-propelled V-1 and V-2 rockets on London and other cities seems understandable. However, many might wonder why there wasn’t a plan to address it in the years following the war. The truth is that in 1967, a serious incident occurred that led to the rejection of any possible idea to salvage the cargo: the Kielce explosion.

One of the buoys marking the wreck site (seen behind).
One of the buoys marking the wreck site (seen behind). Credit: Gil Edwards / Wikimedia Commons

The Kielce was a Polish freighter that sank in 1946 off the coast of Folkestone, a town also in Kent, not far from the previous site, a bit farther south, overlooking the English Channel instead of the North Sea. The ship, sunk 3 or 4 miles from shore and therefore in deeper waters, was carrying a similar amount of explosives to the SS Richard Montgomery, and when they tried to remove them during July of the same year, it exploded.

The explosion was so brutal that it created a 6-meter crater on the seabed, and experts equated the force of the blast to a 4.5-magnitude earthquake on the Richter scale. Despite the distance from Folkestone, panic erupted in the town. Miraculously, there were no injuries, but the impression left was so great that when extrapolating the situation to the SS Richard Montgomery, it was calculated that it would create a 300-meter-wide water column and could launch pieces of the ship up to 3,000 meters into the air, damaging Sheerness’s buildings, and also creating a giant 5-meter wave.

Later, those effects were recalculated downward but would still be destructive, because even if the wave was much smaller, it would still be enough to cause flooding in many coastal towns in Kent. Therefore, all plans to salvage the cargo were shelved, opting instead to declare the wreck as hazardous in nautical charts and mark the exact spot, establishing an exclusion zone around it with visual and radar monitoring.

It was estimated that copper azide (a negative electric charge resulting from the reaction between lead and copper in the bomb components when in contact with water) was very sensitive to causing an explosion, especially if there was a collision with the shipwreck, which was above water, or if the cargo shifted violently due to tides or storms. Today, it’s believed that after so many years, the corrosive effect of saltwater may have acted decisively on the bomb fuses, making them no longer a danger, thus reducing the risk of explosion. This has been stated by the Maritime and Coastguard Agency (MCA).

For added safety, periodic inspections are conducted on the two parts into which the hull split, assessing their structural condition. This deteriorates slowly and progressively, but for now, it doesn’t seem to offer concerning signs of collapse. Consequently, it doesn’t seem like any action will be taken on the wreck in the short or medium term, but you never know because the situation is beginning to have other implications: the construction of the new London airport, which is set to be located in the Thames Estuary (as seen on the map above), has sparked political disputes over whether or not to leave the SS Richard Montgomery there.

This article was first published on our Spanish Edition on November 23, 2018. Puedes leer la versión en español en SS Richard Montgomery, un barco encallado desde 1944 en el estuario del Támesis que está lleno de explosivos


SS Richard Montgomery. Survey Report 2012 (Maritime & Coastguard Agency)| Matthew Anderson, SS Richard Montgomery | The Richard Montgomery (Submerged) | SS Richard Montgomery Matter | Wikipedia

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