Divers have completed their salvage and filming of fishing vessel Jubilee off the Canterbury coast.
The operation is part of an investigation into what caused the 90-tonne vessel to sink last October, killing the three men - Terry Booth, Paul Bennett and Jared Husband - who were onboard.
The Jubilee has been lying 45 metres deep 22kms off the coast ever since.
Two attempts had been made to bring it to the surface and tow it to Lyttelton Harbour so it could be inspected by investigators from the Transport Accident Investigation Commission (TAIC).
The first attempt was stopped after equipment failed with a second attempt also abandoned.
When the weather deteriorated and costs increased further, attempts to tow the sunken vessel were dropped.
However TAIC chief investigator Tim Burfoot said progress had been made as the boat was now 2km closer to the coast in water shallower by 6m.
"That's enabled divers to get a lot more bottom time and enable them to complete the survey that we've asked them to."
On Thursday and Friday divers brought up items that could help explain why the vessel flooded, including parts of its piping system.
"As well as that we've been able to get some extensive video coverage of other items of interest or areas of interest and now we just need to review that video along with the examinations of the other components and hopefully we will get the answer, or some answers, as to why this vessel sank," he said.
He said it was not yet clear whether the investigation would be thorough enough without having the vessel on the surface.
"We won't really know that until we get to examine these items and review the video footage. If we don't get any answers out of that then we'll just have to review our options. But in the meantime the boat stays where it is."