War-time bomb lay dormant for 80 years before exploding under fishing boat

A report into an underwater explosion that rocked the fishing boat Galwad-Y-Mor has been released. 

A report into an underwater explosion that rocked the fishing boat Galwad-Y-Mor has been released. - Credit: MAIB / Crown copyright/ Sarah Prescott Photography

The shocking details of an explosion off Cromer which left a fishing boat's crewmen with life-changing injuries have been laid bare in a new report. 

A German bomb had lain dormant on the seabed since the Second World War 80 years ago until it was disturbed by crab-pot string from the Galwad-Y-Mor, just over two years ago.

Galwad-Y-Mor.

The Galwad-Y-Mor crab boat, which was badly damaged after an explosion on the seabed north of Cromer. - Credit: MAIB/Macduff Ship Design

The bomb detonated, triggering a shockwave and gas explosion that threw the boat out of the water and left the crew nursing a string of serious injuries - including broken arms and legs, and the loss of sight in one crewman's eye.

The crew's two UK nationals and five Latvians were praised in the new Marine Accident Investigation Branch report, released on Thursday. 

It said: "Galwad-Y-Mor’s crew training, experience, length of service together and emergency preparedness improved their survival chances.

A fragment of the steel casing of the bomb that rocked the Galwad-Y-Mor.

A fragment of the steel casing of the bomb that rocked the Galwad-Y-Mor. - Credit: MIAB / 1710 Naval Air Squadron

"Although the physical injuries were significant to five of the seven crew, they were fortunate not to be killed.

"The crew member working on the starboard side of the main deck could have been ejected overboard."

The location where the explosion happened. The Galwad-Y-Mor was 22 nautical miles north of Cromer at the time. 

The location where the explosion happened. The Galwad-Y-Mor was 22 nautical miles north of Cromer at the time. - Credit: MAIB/HMSO and the UK Hydrographic Office

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The report said the bomb likely exploded on the seabed, but if its 123kg TNT and ammonium nitrate explosive had come into direct contact with the Galwad-Y-Mor, it "would have blown the vessel apart".

Damage to the wheelhouse after the explosion below the Galwad-Y-Mor.

Damage to the wheelhouse after the explosion below the Galwad-Y-Mor. - Credit: MAIB / Crown copyright

Damage to the crew mess on the Galwad-Y-Mor.

Damage to the crew mess on the Galwad-Y-Mor. - Credit: MAIB / Crown copyright

The skipper, Lewis Mulhearn, 38, and from Weymouth in Dorset, took a blow to the head and suffered three broken vertebrae, a broken sternum, knee damage, a fractured orbital bone and multiple face lacerations.

Despite his injuries, he radioed for help and made sure his crew were all able to get off the boat into a life raft. Mr Mulhearn was later given a commendation for his bravery. 

Lewis Mulhearn, captain of the Galwad-Y-Mor, was presented with the Emile Robin Award

Lewis Mulhearn, captain of the Galwad-Y-Mor, was presented with the Emile Robin Award by the Shipwrecked Mariners’ Society. - Credit: Sarah Prescott Photography

Remembering the incident, Mr Mulhearn said: "At the time it felt like a big wave, like it was rough seas, but it was a very calm day. When my senses came back to me I thought: something’s not right.” 

The explosion happened on December 15, 2020, at 11.22am, around 22 nautical miles north of Cromer. 

Plans of the Galwad-Y-Mor, showing where the crew members were

Plans of the Galwad-Y-Mor, showing where the crew members were - and what injuries they suffered - in the explosion in the water north of Cromer. - Credit: MAIB/Macduff Ship Design

The crew had been hauling a crab string with about 100 crab pots attached up from the surface 30 metres below.

The report describes the chaos that followed. "Three loud bangs were heard by the crew on the main deck.

"The vessel was thrown about. Propulsion and electrical power immediately failed."

The main deck was deluged with seawater and one crew member’s lifejacket automatically inflated.

The report goes on: "The skipper had hit his head and was dazed; four of the crew were severely injured but all remained conscious.

Damage to the toilet after the explosion on the Galwad-Y-Mor

Damage to the toilet after the explosion on the Galwad-Y-Mor - Credit: MAIB / Crown copyright

When the Galwad-Y-Mor was later lifted out of the water ashore, the twisted port side bilge keel was revealed. 

When the Galwad-Y-Mor was later lifted out of the water ashore, the twisted port side bilge keel was revealed. - Credit: MAIB / Crown copyright

This image shows the switchboard sheared from its mountings after the explosion below the Galwad-Y-Mor.

This image shows the switchboard sheared from its mountings after the explosion below the Galwad-Y-Mor. - Credit: MAIB / Crown copyright

"The wheelhouse equipment was seriously damaged, water flooded onto the main deck, and into the engine room, and the vessel settled low in the water."

The main seawater inlet was sheared and the engine room was flooded to the top compartment. 

Mr Mulhearn sent out a mayday and helped his crew to abandon ship. 

A Coastguard helicopter and RNLI lifeboat were dispatched but it was two fast boats from the offshore wind farm support ship, Esvagt Njord, that was first to the rescue. 

Given first-aid aboard the ship, three crew members were airlifted to Hull Royal Infirmary, while the others were taken ashore by boat, first to Cromer Hospital and then to the Norfolk and Norwich. 

Some of the injured crew needed operations and extended stays in hospital, during which time one of them caught Covid. 

Last October, Mr Mulhearn was presented with the Emile Robin Award by the Shipwrecked Mariners’ Society for his actions.

The crew of the Esvagt Njord were presented with an award by Equinor, which operates the Dudgeon wind farm near the scene of the explosion. 

Members of the Esvagt Njord were presented with an award after rushing to the rescue of the fishing boat Galwad-Y-Mor.

Members of the Esvagt Njord were presented with an award after rushing to the rescue of the fishing boat Galwad-Y-Mor. - Credit: Equinor

Fate of the boat and crew

Mr Mulhearn has told this newspaper that one crew member had already returned to sea, but some have said they would never return to the fishing life.

He said one man, who suffered a fractured skull and loss of vision in one eye, was soon travelling to Russia for an operation to hopefully restore his sight. 

"Apart from that, they've recovered really well," Mr Mulhearn said.

But he said he had still not full recovered from his own injuries. Although he felt "pretty much back to normal" he still had some aches and pains and there were some issues with his eye due to the orbital bone fracture. 

The Galwad-Y-Mor, which operated across the North Sea before the explosion in December 2020.

The Galwad-Y-Mor, which operated across the North Sea before the explosion in December 2020. It is planned she will soon return to the sea after a rebuild. - Credit: Lewis Mulhearn

But Mr Mulhearn said he hoped to resume skippering the Galwad-Y-Mor in four or five weeks. After the blast, she was towed to Grimsby - her home port - and then taken to Hull, where she has been rebuilt for owners, the Galwad-Y-Mor Shellfish Company.

He said: "We'll be back on the same boat and we're hoping it's going to be very soon. She's a good old girl."

An explosive legacy

The bomb the boat encountered was a German SC250 - one of the most commonly used bombs of the Second World War. Many were dropped on the Blitz on London. 

They are still being found buried under building sites, quarries and in the sea as far afield as Ukraine, Macedonia and England. 

A SC250 bomb, at the National Museum of the United States Air Force in Dayton, USA. This was the same kind of bomb

A SC250 bomb, at the National Museum of the United States Air Force in Dayton, USA. This was the same kind of bomb that exploded under the Galwad-Y-Mor off Cromer. - Credit: Greg Goebel

Records indicate around 10pc of the high-explosive bombs dropped during the war did not detonate.

It is estimated there are around 500,000 pieces (or 100,000 tonnes) of unexploded ordnance (UXO) in seas around the UK.  

It comes from German or allied bombs jettisoned from aeroplanes after aborted bombing missions, German air-dropped bombs used to target allied shipping, depth charges, torpedoes and sea mines.

A fragment of the steel casing of the bomb that rocked the Galwad-Y-Mor.

A fragment of the steel casing of the bomb that rocked the Galwad-Y-Mor. - Credit: MIAB / 1710 Naval Air Squadron

When the casing of a UXO remains intact, the explosives inside are not washed away by sea water.

UXO from the two world wars is considered "extremely volatile" and experts tend to dispose of it by controlled explosion rather than try to defuse it. 

Another SC250 high explosive bomb found in the Dudgeon Wind Farm survey area. This bomb was detonated underwater.

Another SC250 high explosive bomb found in the Dudgeon Wind Farm survey area. This bomb was detonated underwater. - Credit: Equinor