What happened

At about 1246 on 11 June 2011, the harbour tug Adonis, with four persons on board, capsized during an operation with a second tug, Wolli, to relocate a barge in the port of Gladstone, Queensland. Three of the persons on board escaped the capsizing tug but the fourth did not and drowned in the tug’s wheelhouse.

What the ATSB found

The ATSB found that while the masters of the two tugs involved with the tow were aware of the risks of tugs capsizing, neither of them realised that Adonis had entered a classic capsize scenario when it moved abaft of the barge’s port bow before the barge had begun to slow down. The barge’s speed was not reduced in time to allow Adonis’s master to regain control of the tug and manoeuvre it back into a safe position ahead of the barge. The tug’s crew were not able to release the towline using the towing hook’s quick release arrangement before the tug capsized.

Investigation of the accident found that the retrospective fitting of a set of ‘H’ bitts to the tug, aft of the towing hook, had a detrimental effect on the tug’s manoeuvrability. The fitting of the ‘H’ bitts, and a towing winch, also resulted in Adonis being unstable when undertaking towing operations over the stern. This fact was not identified by the tug’s owners because the tug’s stability had not been recalculated following the fitment of the additional equipment.

What has been done as a result

Sea Swift, the owners of Adonis, have produced new procedures covering the quick release arrangements on its tugs and enhanced the training and familiarisation of its crews with these arrangements. The company has also carried out a review of all its tugs’ towing and quick release arrangements and introduced regular testing of this equipment.

In addition, a program for the review of all stability data for its tugs which were purchased overseas has been instigated, and an experienced training manager has been employed to review and monitor the company's health and safety policies and practices. A review of Sea Swift’s training assessment for new masters or potential masters for the towing fleet has extended the period of training to include mentoring runs and supernumerary runs with other masters to facilitate the development of a greater understanding of towage requirements.

Safety message

The masters of tugs, regardless of size, need be actively aware of the signs that a tug might be in danger of capsizing and what to do to lessen this danger. For multiple tug operations, the masters of the tugs should plan the passage and consider the speed of passage and when it is time to release the towline. It is also important that the masters regularly communicate during the passage and that any concern regarding speed is immediately brought to the other master’s attention.