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Summary

Summary

The Australian bulk carrier River Yarra sailed from Cairncross dry dock, Brisbane at 0736 on 31 August 1997, with two tugs assisting. A licensed pilot was in charge of the navigation through the pilotage district. The vessel manoeuvred to mid stream where the engine was tested for about eight minutes, initially astern and then ahead.

Although there were some fluctuations in engine revolutions, this was identified as a minor problem with the governor, which could be adjusted when clear of the Brisbane River. Following the engine trials the tugs were dismissed.

Through Brisbane Harbour Control, it was known that the tanker Girraween was inbound for the Ampol crude oil berth at Fisherman Islands and that the two vessels would pass in the approach channel. In view of the fluctuations in River Yarra's engine revolutions, the Pilot asked the Pilot on Girraween to delay entry into the Bar Channel until about 0900 when River Yarra was expected to clear the entrance beacons.

As River Yarra passed Fisherman Islands the tug W J Trotter was seen alongside the container berth. At about this time River Yarra's engine revolutions dropped for no apparent reason and, as a precautionary measure, the Pilot called the tug on VHF radio, asking it to escort River Yarra through the Bar Channel.

A few moments later River Yarra lost all engine power. The ship was making about 10 knots and was able to maintain steerage way for 2 miles. The crew of W J Trotter cast off to follow River Yarra along the Bar Channel and the Tugmaster, advised of the engine failure, was requested to take a tow from River Yarra's forecastle so the bulk carrier could clear the Bar Channel.

The tug arrived at River Yarra and passed a line from its bow to the bow of the bulk carrier. W J Trotter is a stern drive omni-directional tug with the ability to tow with nearly equal power and manoeuvrability in any direction, at least at low speeds.

The tug took the weight on the towline and started to tow River Yarra along the Bar Channel. Shortly after the tug made fast, River Yarra's engine was restarted, however the tug was retained in case of further problems. The two vessels picked up speed and cleared the entrance beacons twenty minutes later. River Yarra then started to alter course to starboard and after an alteration of about 10, the two vessels collided causing damage to W J Trotter's hull on the port side, just aft of its mid-length.

Radio contact between the two vessels established that, although damaged, W J Trotter did not require assistance and would make its way back to its berth. River Yarra continued on its voyage.

Conclusions

These conclusions identify the different factors contributing to the incident and should not be read as apportioning blame or liability to any particular organisation or individual. The following factors are considered to have contributed to the collision:

  1. The initial requirement for a tow at short notice, which arose from a lack of appropriate engine room procedures on board River Yarra.
  2. A feeling by all involved that, once the ship was under tow, the critical operation to prevent River Yarra taking the ground had been completed successfully, before the tug let go.
  3. A lack of precise communications as the vessel cleared the channel between those on the bridge of River Yarra and the Tugmaster of W J Trotter.
  4. The speed of the tow, particularly in the bow-to-bow configuration at the time of letting go.
  5. The short length of the towline increased the risk of being overrun with any slackening in speed by the tug.
  6. The lack of appreciation by the Pilot and Master of the difficulty in controlling the directional stability of W J Trotter when towing stern first at speed.
  7. The absence from Pilot training of a full knowledge of tug manoeuvring capabilities.
  8. The lack of a mutually agreed procedure for letting go the tug.
  9. Inexperience by both the Pilot and Master of releasing a tow at relatively high speed.
  10. The absence from the tug's standard operating procedures of information on the limitations of the tug's performance when towing astern.
 
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