The Marine Accident Investigation Branch (MAIB) has recently published their report into the subsea explosion that resulted in significant vessel damage and crew injuries to a 15m crab potting vessel which occurred 20nm off the coast of North Norfolk (immediately south of Cromer Knoll) in December 2020,.

While recovering a string of crab pots during daylight hours, the line became snagged on a seabed obstruction – now believed to be a WWII German 250kg high explosive air dropped bomb – which subsequently detonated on the seabed 30m below the vessel. The resulting shock wave and gas bubble from the explosion struck the fishing vessel causing extensive deformation to hull plating, the engine room to be flooded and severe shock damage to all internal compartments.

The seven crew members onboard received significant injuries, several of which were life changing, but fortunately there were no fatalities. The images below illustrate the nature of the damage incurred.

THIS INCIDENT IS A GRAPHIC REMINDER THAT ORDNANCE ARE DESIGNED TO KILL AND MAIM THIS POTENTIAL REMAINS EVEN AFTER ITEMS HAVE BEEN SUBMERGED FOR DECADES

THERE IS NO SUCH THING AS A ‘DUD’ – and the fact that an item has been disturbed and moved does not mean that it is ‘safe’.

Munitions are classified as either ‘inert’, ‘live’ or ‘blind’. An item that has been fired (or dropped) and failed to function is considered ‘blind’ and therefore potentially highly dangerous.

Any munitions or ordnance discovered onboard aggregate dredgers or at wharves must be reported in accordance with the principles set out in the guidance ‘Dealing with munitions in marine sediments’ (2010), produced by the British Marine Aggregate Producers Association (BMAPA), the Mineral Products Association (MPA) and The Crown Estate in consultation with the police, Health & Safety Executive (HSE), Maritime & Coastguard Agency (MCA) and Joint Services Explosive Ordnance Disposal (EOD).

The principles contained within this guidance should be embedded within company policies, practices and procedures for every vessel and wharf where this potential risk exists.