In its latest Safety Digest, the UK MAIB analyzes the flooding of a fishing vessel while underway and the rescue of its two crew onboard by an RNLI lifeboat. The investigation revealed that the weight and location of the fish catch can significantly affect the vessel’s stability. The fishermen were uninjured and the actions of the RNLI crew prevented the potter sinking.
The incident
The skipper and his crewman were returning to harbour having caught 800kg of crabs and re-shot their pots. The crabs had been stowed in boxes on the aft end of the deck and were secured ready for the passage back to the boat’s home port. The skipper set his course and increased to full speed.
A short while later, the boat’s engine space bilge alarm sounded and the skipper investigated. When he opened the engine space hatch cover, he saw flood water lapping over the engine sump, so immediately started the boat’s bilge pump. The bilge pump worked for a short while, but its suction line quickly became blocked with rubbish from the bilges.
Concerned by the amount of water in the engine space and the loss of his bilge pump, the skipper called the coastguard on his VHF radio and alerted the watch officer to his situation, advising that he was heading back to port as fast as he could. The coastguard watch officer upgraded the call to a “Mayday” and re-broadcast the boat’s information on VHF radio channel 16. He also tasked the local RNLI lifeboat to attend the scene and provide assistance as required.
When the RNLI lifeboat reached the potter, the skipper shut down the boat’s engine and the lifeboat crew used one of their salvage pumps to pump the water from the engine space. The fishermen were transferred across to the lifeboat and the potter was towed back to its home port.
Once securely tied alongside, the fishing vessel was pumped dry and the hull examined internally to identify the source of the flooding. No obvious cause of flooding could be seen and the bilge remained dry. The next day, the skipper engaged a local diver to inspect the hull and propeller shaft to seek any indications of the location of the water ingress. However, again none were found.
A subsequent inspection of the engine space hatch cover identified that it had not been properly secured and was not watertight. It was apparent that the 800kg of crab stowed on the aft end of the deck had a significant impact on the potter’s freeboard and its trim. This had caused water to wash over the deck and enter the engine space through its access hatch while the boat was motoring at full speed. The blockage of the bilge suction further compounded the crew’s concerns.
The coastguard’s timely escalation of the skipper’s VHF report to a full “Mayday”, and resultant mobilisation of the lifeboat, prevented the fishing boat from sinking and the crew probably ending up in the water, UK MAIB underlined.
Lessons learned
- Weathertight spaces should be weathertight. All boat owners and operators are reminded that external doors and hatches should always be closed and dogged down at sea, and regular checks should be made of their seals to ensure weathertight integrity is maintained.
- In addition to causing water to wash over the boat’s working deck, the weight and location of the catch almost certainly had an adverse impact on the potter’s stability. Skippers should make every effort to assess the stability of their boats and set a maximum safe load for their catch. They should also ensure that their catch is stowed as low in the boat as possible so as to not compromise their boat’s stability, and distribute it to maintain an upright attitude and an optimal trim for the boat when underway.
- The blockage of the bilge suction meant that the skipper’s only mechanical method of pumping the water from the engine space became unusable. The correct operation of bilge pumps is safety-critical on any boat. It is therefore crucial that bilges are kept clean and free from detritus that could prevent bilge pumps from working properly.
