Mahia near-capsize at Auckland Harbour (2000)

Classification

• Incident Type: Capsize girding
• Severity: High
• Primary Source: Transport Accident Investigation Commission Report 00-208

The controlled incident type is retained, but TAIC described a near-capsize rather than a completed capsize. It found that, without the towline parting, Mahia would likely have capsized.

Vessel Details

Incident Details

Key facts

• Mahia assisted the bulk carrier Dorthe Oldendorff as it departed Chelsea Wharf under pilotage.
• At about 0900, propeller wash and towline loading caused the tug to heel heavily; its deck edge was substantially submerged.
• The towline parted and the tug righted itself, throwing its deckhand into the water; a pilot launch recovered him.
• TAIC found that inadequate communication, reduced awareness at the ship’s stern, and the absence of a rapid mechanical release for the towline were safety issues.

Narrative

On 5 July 2000, Mahia assisted the bulk carrier Dorthe Oldendorff during an unberthing manoeuvre from Chelsea Wharf in Auckland Harbour. The ship was under pilotage, with Mahia working aft and the harbour tug Waka Kume assisting forward. After the vessel had turned into the channel, the pilot instructed Mahia to stop pulling and stand by to let go.

The towline was slack while Mahia waited. The ship’s stern then swung past the tug, leaving it astern and beam-on to the propeller wash. When the ship’s engine was put ahead to arrest sternway, the wash pushed the tug astern and the towline came tight. TAIC found that the tug heeled heavily, with its deck edge substantially submerged. As the engine stopped, a further surge of water increased the heel; the towline then parted and the tug rapidly righted itself.

The deckhand had been on the aft deck ready to retrieve the line. He was thrown overboard when the tug righted, but a nearby pilot launch recovered him and returned him to Mahia. TAIC recorded no injuries. The tug retrieved the remaining towline and continued to its next assignment later that day.

TAIC concluded that the towline parted after Mahia was caught beam-on to the ship’s propeller wash. It found poor communication between the ship’s bridge team and mooring stations, insufficient awareness of activity at the stern, and the tug’s limited ability to remain clear of the wash. The report also found that the deckhand had insufficient time to cut the line, and that a mechanical quick-release device might have enabled release before the tug was pulled over.

The investigation did not attribute the occurrence to fatigue: it found both the pilot and tug skipper appropriately qualified, experienced and sufficiently rested. TAIC also found that the two tugs could have safely completed the manoeuvre if the bridge team had remained conscious of Mahia’s limited power and manoeuvrability.

Sequence of events

Contributing factors

Investigation

The Transport Accident Investigation Commission investigated the occurrence as Report 00-208, Tug Mahia near capsize, parted towline and man overboard. It found that the towline parting prevented a likely capsize. TAIC recommended that the Director of Maritime Safety clarify the requirements for positive, rapid towline release and examine the use of fixed bollards in ship-handling operations.

References

• TAIC Report 00-208: Tug Mahia near capsize, parted towline and man overboard

Related

• Mahia
• Other
• Transport Accident Investigation Commission (TAIC)
• Girding
• Capsize Girding
• Tug Incident Classification

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