Apr 032015
 

Safety Digest from the UK’s Marine Accident Investigation Branch, MAIB, frequently covers the more unusual ways of causing grief aboard ship and the latest issue is no disappointment: It reports and incident in which a vessel was flooded by own freshwater tank.
Says MAIB: “Poor planning and lack of procedures led to approximately 100 cubic metres of fresh water flooding accommodation and machinery compartments on board a large cargo ship.”

Figure 1

Figure 1. Flooding on the deck

Due to the scheduled programme at the ship’s next port, a routine inspection of a fresh water storage tank was conducted on passage. The chief officer was responsible for the management of the fresh water and he delegated the task to the AB ‘waterman’. The ‘waterman’ was told which tank to inspect and that the tank had been emptied. The ‘waterman’, who was familiar with the tank inspections on other ships, arranged for another crewman to assist. Neither crewman had inspected the water tanks on board.

The two crewmen went to a compartment in the accommodation block where they thought that the tank lid was located. They then removed the lid’s securing nuts and one of the crewmen levered it out of position. As he did so, the tank lid was projected across the compartment by the force of water coming from the tank below, narrowly missing one of the crew members as it did so. Wrong tank!

flood2

Figure 2. Top of stairway

Water quickly flooded into the compartment and one of the crewmen quickly escaped through the open door. However, the door was soon forced shut by the flood water, trapping the second crewman inside. As the water depth increased to about 2m, he was forced to climb onto a bench sink. The trapped crewman was subsequently rescued by the ship’s emergency<

flood3

Figure 3. High voltage converter space

The water spread rapidly into all compartments on two decks (Figures 1 and 2), including the high voltage converter space (Figure 3).

Quick action by the ship’s crew to isolate the power supplies to the high voltage equipment prevented serious damage to the propulsion system. Nonetheless, the ship drifted not under command for several hours until temporary repairs were completed.

The Lessons

  1. Any tank, regardless of its contents, is a dangerous enclosed space. The safety of crew engaged in tank work, including fresh water tank inspections, relies on a proper risk assessment being undertaken and access controlled by a permit to work system. Anything less has the potential to be very costly.
  2. Assuming that a crewman is familiar with a task due to his or her routine duties during their previous contracts on other vessels, is a frequently repeated mistake. Remember that all ships vary and people are different. It pays to double check that any person assigned to do a safety- critical job has been properly briefed, fully understands how to complete the job in a safe manner and is supervised appropriately.
  3. The clear, consistent and unambiguous marking of all tank lids, sounding tubes, vent pipes etc is such a simple and inexpensive way of identifying what a tank is and what it contains. It is such a shame that it is not always done

MAIB Safety Digest

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