An incident where two crew members of a fishing vessel were asphyxiated during a fish tank cleaning operation could have had a “far more serious outcome” but for a number of factors, the Marine Casualty Investigation Board (MCIB) has said.
These factors included proximity and response of emergency services and some actions of the crew, along with the short distance to a hospital accident and emergency department, the MCIB says.
The incident occurred on the 24-metre fishing vessel Ardent, owned by Orpen Fishing Company Ltd of Castletownbere, Co Cork on October 31st, 2022.
It had left Port Oriel, Clogherhead to pair with FV Cisemair on fishing grounds in the Irish Sea, and was underway when the watch was transferred from the skipper to another crewmember, allowing the skipper to conduct the fish tank cleaning in preparation for the filling and cooling of the seawater within the tanks.
Both the skipper and crewmember were removing fish/waste product trapped in various locations within the fish hold/tank with limited airflow via the deck coaming access hatch.
The report says that the first “casualty” was overcome while passing below the tank centre boards. The second “casualty” was overcome while checking the condition of the first “casualty” who was lying on the tank floor.
The investigation says that a mixture of rotting fish and seawater was held within sections of the refrigerated sea water (RSW) system piping, cooler and valve chest below the shelter-deck over a prolonged period (approximately 150 hrs), at a temperature of approximately 15°C.
This produced dangerous levels of toxic gases that may have included: hydrogen sulphide, ammonia, hydrogen cyanide or carbon dioxide.
It says that both casualties were overcome by the toxic atmosphere when they lowered their heads into the “toxic pool”.
The vessel was turned around immediately, and returned to Port Oriel at a maximum speed of 9.4 knots before tidal constraints restricted access, while the Cisemar was asked to notify emergency services.
The vessel was brought alongside and secured with the aid of emergency services shore teams.
The two crew were treated in hospital, with one remaining in hospital for a number of weeks.
The MCIB recommends that the Minister for Transport should review the content of marine notices number 43 of 2016 and number 24 of 2009 and issue an updated marine notice warning crews on fishing vessels of the hazards associated with toxic gas generation and retention in RSW systems.
It makes other recommendations relating to enclosed space entry techniques, raising awareness of the correct use, maintenance and calibration of personal atmospheric monitoring systems, rescue equipment and recovery techniques.
It says crewmembers should participate in an appropriate drill and relevant codes of practice, and recommends the minister should review existing legislation on the requirement and application for onboard rescue breathing apparatus and training for confined spaces.
A breathing apparatus requirement should also apply to vessels with RSW systems installed,the report says.
The full MCIB report is here
