Maritime New Zealand and the agency set up to investigate transport accidents remain at loggerheads over the sinking of a fishing boat two years ago.
Nine people were on the Kotoku when it capsized in Foveaux Strait off Stewart Island in May 2006. Six people, including two children, died.
The final Maritime New Zealand report into the sinking of the vessel has found that she was seaworthy.
However, an earlier report by the Transport Accident Investigation Commission highlighted system failures, including the ship inspection system not detecting the boat's unseaworthy condition.
The latest report says the vessel suffered a critical loss of stability when struck by two large waves, and an independent expert found that the fishing boat was seaworthy at the time.
Deck modifications, the closure of slots to allow water to escape on the deck and the vessel being exposed side-on to the waves also contributed to the sinking, it says.
Maritime Safety says safety recommendations made by the Transport Accident Investigation Commission are being dealt with and work to improve maritime safety is continuing.
It says an independent expert found the Kotuku was seaworthy and compliant with stability requirements before the sinking.
Maritime New Zealand says tests to determine the seaworthiness of the boat could not be relied on because of the vessel's condition after sinking.
John Mansell from Maritime New Zealand says it believes the vessel was seaworthy. He says the boat was badly damaged as it sank and was salvaged, making a true assessment difficult.
Skipper considers legal action
Kotutu's skipper and owner John Edminston says he is considering legal action against the Transport Accident Investigation Commission.
John Edminston, who was on the boat when it capsized, says the commission's report is ambiguous and biased. He believes the agency should be disbanded.
The commission says it stands by its report.