IMCA provides lessons learned through an incident where an ensuing explosion caused a shock wave that threw a boat about, resulting in significant injuries to five of the seven crew and major damage to the vessel’s hull and machinery.
The incident
A 15m crab potting vessel was hauling pots in the North Sea approximately 22 miles north-east of Cromer. The crabbing gear disturbed a 250kg unexploded WWII bomb, which went off on the seabed 30m below the vessel.
As informed, the ensuing explosion caused a shock wave that threw the boat about, resulting in significant injuries to five of the seven crew and major damage to the vessel’s hull and machinery.
After the bomb went off, 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 personal flotation device (PFD) automatically inflated. The skipper had hit his head and was dazed; four of the crew were severely injured but all remained conscious.
Following the incident, 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 skipper roused the night watchman and made a distress call with a handheld VHF radio on channel 16.
Unsure that the distress call had been received, he texted the skipper of another fishing vessel and requested that a distress message be relayed to the coastguard. Galwad-Y-Mor’s skipper launched the life raft with the help of a crew member and ordered the crew to prepare to abandon ship.
The injured crew were transferred to hospital by helicopter and RNLI lifeboat and treated for head, back and knee injuries.
Probable cause
The string of pots the crew were attempting to recover at the time of the explosion most likely became fouled on an SC250 bomb. It is possible that the bomb was dragged along the seabed and caught on an obstacle, such as a boulder, causing the potting string to tighten on the hauler. As Galwad-Y-Mor’s skipper increased vessel power, the disturbance of the bomb caused either an unstable fuse to activate or explosive charge degradation products to detonate and this resulted in the bomb exploding on the seabed.
Lessons learned – What went right
- The crew’s actions after the explosion were both prompt and effective; five of the seven crew were significantly injured and yet they were able to send a distress message, launch a life raft, and evacuate to rescue boats provided by the nearby offshore support vessel Esvagt Nord;
- It is likely that Galwad-Y-Mor crew’s formal training, emergency drills, and combined length of onboard service prepared them to deal with this unforeseen emergency scenario and enabled them to take swift action that, undoubtedly, saved lives;
- The emergency response and rescue that offshore support vessel Esvagt Njord provided was also prompt and effective. The onboard triage of the casualties was aided by the presence of a trained paramedic and increased the survivability of Galwad-Y-Mor’s injured crew members;
- Galwad-Y-Mor’s hull was well constructed and able to withstand the force of the nearby seabed explosion;
- Galwad-Y-Mor was successfully salvaged and has been rebuilt.
