KEY POINTS:
Two large waves hitting the Kotuku side-on led to the boat's sinking and the resulting loss of six lives, a final report from Maritime New Zealand (MNZ) concludes.
The 14.2-metre wooden fishing vessel sank off Stewart Island in May 2006, with the loss of six of the nine people on board.
The dead included nine-year-old cousins Shain Topi-Tairi and Sailor Trow-Topi, their grandfather Leslie (Peter) Topi, 78, Sailor's mother Tania Topi, 41, Clinton Woods, 34, and Ian Hayward, 52.
The MNZ report said the vessel suffered a critical loss of stability when the waves struck it and the impact was made worse by Kotuku's heightened centre of gravity.
Deck modifications, closure of the vessel's freeing ports, which allow water to escape, and the helmsman's attempts to put the stern into the waves, exposing her side-on to the oncoming sea, compounded the problem.
The final MNZ report follows a report released in April by the Transport Accident Investigation Commission (TAIC) which said the Kotuku was unseaworthy and should never have passed statutory inspections.
TAIC highlighted the "repeated failure" of MNZ's ship safety inspection system to identify problems with the boat.
It also noted lifesaving equipment was either not working or missing and said the skipper had not followed correct procedures.
The MNZ report said the prime reason for the sinking was the large waves it encountered and it was difficult to say to what extent the tragedy could have been minimised if various factors such as safety equipment and preparation had been improved.
However, it said the liferaft had failed to release when the vessel sank.
If it had done so immediately after capsizing, it was likely some of the the lives could have been saved.
MNZ also found the skipper was in breach of compliance and safety issues and that there were downfalls in MNZ's own safer ship management system (SSM).
MNZ said it had responded by contacting all SSM companies and instructed them to ensure all vessels were compliant with certain criteria.
It had also strengthened its oversight of recognised surveyors by revising the content and format of its six-monthly seminars for them.
"MNZ has also taken the opportunity to review the way in which services are delivered by its own employees," it said.
A string of other safety recommendations have been enacted within the maritime industry in terms of enhancing safety issues and awareness.
MNZ director Catherine Taylor said the Kotuku investigation had been a long and demanding process and one of the most intense it had ever undertaken.
Among the evidence collected were tests of the recovered vessel by an independent maritime expert, who found the Kotuku was seaworthy and compliant with all stability requirements prior to her loss, Ms Taylor said.
She said that needed to be considered in light of two separate tests which reached different conclusions about the Kotuku's seaworthiness.
The event was nevertheless a tragedy and MNZ sympathised with all the whanau, families and friends of those who were lost.
"We thank them for their courage and their help in assisting us during what has been a long and difficult process for all involved.
"We now hope that the release of the report now brings some measure of closure," she said.
- NZPA
