Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation.
On 29 January 2021, at 0655 Coordinated Universal Time, a multi-purpose vessel encountered heavy seas in the Southern Ocean. The 6-metre swell and confused sea state  caused the vessel to roll heavily, listing more than 30 degrees. As a result of this movement, several bundled wire restraints on battery racks failed and numerous batteries fell to the floor of the top deck battery room (Figure 1).
Wires to the batteries were cut and at least two of the batteries short circuited internally between the cells. This resulted in a fire, which triggered an alarm on the bridge. The captain initiated the emergency response procedures and the fire was extinguished.
Figure 1: Battery room after the fire was extinguished
Source: Vessel operator
The battery room contained multiple shelved racks with large batteries secured to them. These racks used an L-shaped frame to prevent fore and aft movement, and metal brackets or bundled wires to prevent any lateral movement in the rack. The batteries that fell from the racks, including the two that had confirmed fire damage, were secured by bundled wire straps. These had been
installed 5 months prior to the occurrence. The other batteries were secured to the racks by heavy metal brackets that bolted into the rack frame. Figure 2 depicts a battery secured with both types. The large brackets were the normal method of restraint and it could not be determined why they were not used to secure the more recently delivered batteries or why some batteries were secured by both types of restraints. The bundled wire straps proved to be inadequate in the heavy swell of the Southern Ocean.
Figure 2: Battery rack with both types of restraints
Safe Work guidance
While there are no mandated standards for battery racks on ships, securing loose items prior to departure is a key principle of good seamanship. The Seacare Authority Code of Practice Approval 2018 - Health and Safety in Shipboard Work, including Offshore Support Vessels (paragraph 12.5) stated 'Batteries should be kept battened into position to prevent shifting in rough weather’. In this occurrence, the batteries were secured, although inadequately so for the prevailing conditions. The departure checklist used by the operator included securing loose items above deck in preparation for heavy weather and was completed by the crew.
The operator of the vessel advised the ATSB they have taken the following safety actions:
- all battery rooms were checked for suitable sea fastening
- the bundled wire securing bands were immediately replaced with the original metal securing brackets or another equally robust arrangement
- damaged batteries were replaced as required
- a meeting with involved parties was held to discuss the lessons learned and corrective action.
Although believed to be sufficient at the time of installation, the methods used to secure the batteries were inadequate for the conditions experienced in the Southern Ocean. At sea, particularly in heavy weather, unsecured items risk being damaged and may also pose a danger to the crew, or, as in this case, the safety of the ship. The risk to life associated with an emergency such as a major shipboard fire, is significantly increased when it occurs in heavy weather, far out to sea, where any possibility of assistance from ashore or from another ship is significantly reduced.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.