Initial findings into August’s tragedy onboard the Fraserburgh-registered Sunbeam have found it nearly resulted in “multiple fatalities”.
Second engineer William Ironside died after being overcome by lethal fumes while cleaning the vessel’s tanks.
The Marine Accident Investigation Bureau (MAIB) last week issued a safety bulletin in which it called for improved risk assessments and safe operating procedures for the crew with regards to refrigerated saltwater tanks.
MAIB said its investigations into the fatal accident continue and that a full report will be issued upon its completion.
It said that a crew member had raised the alarm when Mr Ironside was found lying unconscious at the aft end of the tank.
The MAIB said: “Three of the vessel’s crew entered the tank and tried to resuscitate the second engineer but they soon became dizzy, confused and short of breath.
“One of the crew managed to climb out of the tank unaided, the other two crewmen and the second engineer were recovered onto the open deck by two crewmen wearing breathing apparatus.”
While the two crewmen made a full recovery, tragically the second engineer could not be resuscitated and died.
In its initial findings, the MAIB said tests of the atmosphere in the tank showed that the oxygen levels were dangerously low.
Oxygen at the bottom of the tank was less than 6% when the normal level should be 20.9%.
Further tests of both the tank atmosphere and residual water samples showed the presence of Freon R22, the refrigerant gas used in the RSW tank’s refrigeration plant.
Freon R22 is four times heavier than air and will displace oxygen at the bottom of an enclosed space, such as an RSW tank.
This toxic, tasteless and mostly odourless gas. If it is deeply inhaled, it can cut off vital oxygen to blood cells and lungs.
The MAIB stated: “The RSW tanks on board Sunbeam were, by design, enclosed spaces that did not have a fixed means of positive ventilation.
“Such spaces can become dangerously hazardous to life. The atmosphere in the tanks can become oxygen deficient through the effects of corrosion, or toxic through the decomposition of sludge, fish or, as in this case, the accidental release of gas."
The MAIB continued: “This was a tragic accident, which nearly resulted in multiple fatalities. The crew did not appreciate the levels of risk they were taking, even after the second engineer had collapsed.”
Sunbeam’s owners have now been urged to conduct risk assessments for entering and working in RSW tanks.