Correction: An earlier version of this story incorrectly attributed several quotes to Harbourmaster Grant Nalder.
Acting Prime Minister Winston Peters has alleged a cover-up at KiwiRail over the grounding of the Aratere last month.
The troubled Interislander ferry is expected to sail from Picton to Wellington on Thursday for the first time since 21 June, under strict safety conditions.
There were allegations from coalition government partner New Zealand First earlier this week the accident last month happened after "someone put the autopilot on, went for a coffee, and then couldn't turn the autopilot off in time when that someone came back".
Party leader Peters on Thursday morning appeared to distance himself from the claim, before doubling-down on it.
Asked on Morning Report why the party had made the allegation - posted to X (formerly Twitter) on Tuesday - Peters said RNZ would "have to ask the party that".
"But here's the point - at the moment we heard this story, it was clear as daylight that something dramatically had gone wrong, that shouldn't have gone wrong, and we find out it was on autopilot."
Documents sent to staff last week and leaked to the media confirm the ship's autopilot was involved, but said nothing about an inattentive staff member taking a coffee break.
The Aratere departed Picton in line with normal conditions and on time, and as the vessel passed Mabel Island - which is a short way out of the berth - the team switched from hand steering onto autopilot," the document said.
It appeared from that point, a crew member had inadvertently hit an execute button, causing the vessel to alter its course in a way it would do around about one nautical mile further along. As this happened early and steered it towards the shore.
The crew after that point struggled to return it to manual steering mode, and it took around about a minute before the crew was able to apply reverse thrust and have control of the steering - at which point it was too late.
Peters said the party had sources on the boat itself, which relayed the 'coffee break' claim.
"There's investigations under way, but they've had to be honest and tell us that the allegation made by New Zealand First about the autopilot was in fact true. Now, are you concerned to know that, or are you concerned to have an argument about waiting for a month while they cover their backsides, so to speak?"
"They are responsible to you. You're a taxpayer-owned operation as well. They're required to tell you, the New Zealand public who own them, the truth right here right now. We don't need a month-long inquiry or three or four months while they try and do PR and damage control and cover their butts. Tell us the truth right here right now."
Asked directly if he thought there was a "cover-up" at Interislander operator KiwiRail, Peters said he knew there was.
"I am the acting prime minister, and the reality is that we are wanting to hear the truth, but we don't want to delay any longer. And in a way, you can say I'm asking KiwiRail [to] front up - right here right now."
In the afternoon, State-Owned Enterprises Minister Paul Goldsmith said the time taken for the investigation was appropriate.
"As I said on the news last night, as a shareholding minister of KiwiRail there is independent investigations going on in the maritime space and that's absolutely appropriate and they'll be carried on as they are."
"Look, investigations and accidents take a lengthy amount of time generally and that's absolutely appropriate, they've got to do the job properly."
KiwiRail general manager of Interislander operations Duncan Roy said there was "absolutely no cover-up".
"The ship was clearly grounded, the nation saw that, the nation saw us recover it in 24 hours, they saw it done with no injuries, with no environmental damage, and they've seen it in Picton," he told Midday Report.
"I can state there's no cover-up. We've been engaging in the proper process and with a concentration on getting the facts and being fair and reasonable to our people as we go through this investigation."
The new steering system installed in late May or early June would be part of the investigation, but the Aratere did 77 crossings without problems after it was put in, he said. It was separate to the autopilot system on the ship since 2007.
Merchant Service Guild vice president Iain MacLeod said there was no basis whatsoever to New Zealand First's accusation.
"The vessel had just had two hours in Picton - the bridge crew would have been well-rested prior to departure, and I would be sure they'd have had a coffee in the mess room before doing their pre-departure checks," he told Morning Report.
"So absolutely no basis whatsoever to Nescafe-gate or whatever they called it."
Just why the autopilot was not immediately able to be cancelled "is part of the ongoing investigation", the document said. Maritime New Zealand and the Transport Accident Investigation Commission (TAIC) were running independent probes into the incident, in which no one was injured.
The ferry is due to sail to Wellington on Thursday and harbourmaster Grant Nalder said precautions were in place.
"Aratere [is] staying further off the coast - what they used to do in the rough southerly weather," he said.
There will be a tug waiting to escort the ferry in the harbour, and the vessel would not be passing any other traffic in the narrow part of the harbour, he said.
"That's not an unusual thing for a ship that's had problems.
"Maritime New Zealand is working through a process of getting her back to normal operations, so she's not yet cleared for full operations for passengers.
"In terms of the return today, the autopilot won't be in use, it's going to be hand-steering so the system that for whatever reason played a part in the grounding won't be a part of today's voyage."
Political response
Labour leader Chris Hipkins was unimpressed with New Zealand First posting the claim to social media, rather than sharing whatever information it had with investigators.
"[New Zealand First leader] Winston Peters is the deputy prime minister in the government, I think he should have a slightly higher standard for himself than that."
He said he had seen no evidence of the claim.
Prime Minister Christopher Luxon, overseas at a NATO conference, said there would be "a lot of stories and rumour around what actually did or didn't happen".
Asked if he was comfortable Peters - the deputy prime minister - had been among those commenting on what might have caused the grounding, Luxon said he had not seen what Peters had said or done, but a process was in place and the government would respond once the reports were completed.
"We have a TAIC investigation up and running and also a Maritime New Zealand investigation up and running. I'll wait to see those formal reports before I pass any comment."
Maritime New Zealand says conditions for Thursday's resumption of sailing include initially carrying crew and rail freight only, with no dangerous goods or passengers, and a tug escort when not in Cook Strait.