Report: Increased Workload and Shift Changes Increase Risk of Error
The Australian Transport Safety Bureau (ATSB) has released the final report into the ingress of water into the steering gear compartment of the cement carrier Goliath in the Bass Strait on March 7, 2018, highlighting that disruptions to a crew’s routine, increased workload and shift changes can increase the risk of errors, especially during short sea voyages.
The ATSB found that, on the day of the incident, the crew were involved in a number of tasks, including ballast water exchange, cargo inspections and onboard training across a number of shift changes. During the ballast water exchange, a crew member coming on shift was not provided with information about the status of the valves to and from the after peak tank before continuing the water exchange. Shortly after, seawater was found in the steering gear compartment.
The report reminds operators and crew that careful attention to detail is required to complete tasks and ensure up to date information is provided at shift changeovers.
Details of the Incident
At about 1454 Eastern Daylight Saving Time, the 143-meter, self-unloading cement carrier arrived in Melbourne, Victoria, after a 21-hour voyage from Devonport, Tasmania. Cargo operations commenced and continued into the following day. At about 2330 on March 6, the master was informed that there were problems with the cargo quality making it difficult to discharge, and consequently departure would be delayed. At midnight, the third mate completed his cargo watch and prepared for the vessel’s departure but, as departure was delayed, at 0200 he was relieved of his duties by the master and retired for rest. The chief mate was roused from sleep at 0230 to attend to the cargo issues and cargo discharge was completed soon thereafter. The chief mate then remained on duty for departure and for his normal 0400 to 0800 navigation watch.
At 0315, on March 7, under the guidance of the pilot, stand-by for departure was called. At 0718, Goliath commenced sea passage bound for Devonport. At 0800, the chief mate handed the navigation watch to the third mate. During watch handover, in addition to navigation information, the planned ballast water exchange operation was discussed. The chief mate also advised that he would be inspecting the cargo holds during the morning.
In addition to normal navigation and shipboard routines, a shore-based trainer had embarked in Melbourne to conduct a program of onboard training during the voyage to Devonport. Two sessions were to be held, from 1300 to 1500 and 1530 to 1730. The navigation watches were altered to allow the rostered officer of the watch to attend one of the training sessions.
At 0815, the third mate, as OOW, commenced the routine ballast water exchange as required under the ship’s ballast water management plan. Ballast movements followed a prescribed sequence and timing, as laid out in the plan. The ballast pumps and remotely operated valves were controlled and their status (open or closed) monitored by the OOW from the ballast control panel located in the ship’s wheelhouse.
Assistance around the ship was provided by the duty integrated rating who operated manual ballast valves, sounded tanks (measured water levels) and removed tank access covers as required. There was no way to remotely monitor the status of the manual valves and no record was routinely taken of the valves in use and their status. Verification of the manual valve status was reliant upon communications between the OOW and the duty rating, via the ship’s handheld UHF radios.
Goliath’s ballast system consists of 11 tanks. 10 tanks are located forward of the engine room and one tank aft, the after peak. The system is serviced by two 500 m³/hr ballast pumps via a ring main which could be split via an isolating valve at the bow. This allows Number 1 ballast pump to be configured to service the after peak tank and the starboard side ballast tanks, and Number 2 pump to service the fore peak tank and the port side ballast tanks. This effectively segregated the two pumping systems, was the usual configuration, and was in use on March 7.
At 1200, the second mate took over the watch and the ballasting operations. Elsewhere, the chief mate had completed hold inspections and rested until 1500 after which he was scheduled to attend the training. The second mate attended training from 1300, and the third mate returned to the bridge at that time to take the watch.
At 1420, the ballast system was configured to complete the after peak tank water exchange. At 1453 the second mate returned to the bridge to again take over the watch. However, the third mate retained the watch to complete the after peak tank ballasting which involved lowering the level to 8.5 meter for ship stability requirements.
At 1500, the third mate contacted the duty rating and asked that the two after peak manually operated valves be closed. For reasons that could not be determined, the requested valve closures were not actioned. The third mate did not confirm with the rating that the message had been received and actioned, so he was unaware that the valves connecting the after peak tank to the starboard ballast main had not been closed.
The watch was handed to the second mate who then continued with the next scheduled ballast movement of exchanging the water in the fore peak tank, also unaware that the valves to and from the after peak tank remained open. The third mate left the bridge and attended training before going to bed. The chief mate attended the same training session, and the second mate remained on watch beyond 1600, when the chief mate usually took the watch.
At 1620, flow-through water exchange of port and starboard ballast tanks commenced. This involved the use of both ballast pumps and systems. At 1730, the chief mate came onto the bridge and took over the watch.
At 1736, an engine room alarm (aft bilge well high level) activated and the duty engineer (first engineer) responded. Upon entering the engine room, the first engineer noticed water flowing over the doorstep through the open steering gear room door. This water drained to the aft engine room bilge, resulting in activation of the alarm.
The first engineer discovered water coming from a scupper pipe in the steering gear room, which drained into the steering flat bilge well. This bilge well was not fitted with an alarm and was manually drained to the engine room bilge. Consequently, it had overflowed, leading to flooding of the deck to a depth of about 10cm. The water then overflowed the doorstep, into the engine room, and to the aft bilge well.
The first engineer noted that the water was salt water but could not find an obvious source in the adjacent spaces. He contacted the chief engineer and the bridge, informed them of the flooding, and inquired about the ballasting process. He also contacted the third engineer and requested he attend the engine room to assist. The first engineer then returned to the engine room to begin transfer of the aft bilge well contents to the bilge holding tank.
At 1745 the ballasting operations were stopped and tanks sounded. The after peak tank sounded at three meters higher than at the completion of after peak tank ballasting at 1500. At 1752, after checking stability conditions, the chief mate started pumping down the after peak. The chief mate also directed the duty rating to check the after peak tank ballast line valves. Both valves were found to be open.