Interislander's boss has been questioned about an email sent to customers on the same day one of its ferries ran aground.
The email boasted of the Aratere, which remains stuck in mud and sand near Picton on Saturday after running aground overnight, being "back in service following an upgrade to the steering system during the ship's wet dock last month".
Interislander executive general manager Duncan Roy said the email was referring to a "comprehensive" upgrade to several systems on the ship as part of a "detailed maintenance programme".
"That was about three weeks ago that finished," he told reporters on Saturday.
Roy said the steering mechanism was replaced as part of that work.
"We brought in experts from overseas and that was part of our commitment to improving the maintenance and reliability of the ferries to continue the 99.6 percent reliability we've had for the last six months."
The ship running aground on Friday night was a "significant incident", he said.
KiwiRail - which operates Interislander - said it was "disappointed with what's happened" given the amount of maintenance work undertaken.
"It's serious that we've had a ship grounded so we'll look to the root-cause investigation, but we have invested significant money and time recently in upgrading the steering system," KiwiRail chief executive Peter Reidy said.
He said KiwiRail was taking the matter "extremely seriously".
"We are lucky that it's just in the shallow bit of water here," he told journalists in Picton. "But I think the core thing for us to understand is the root cause.
"The first thing [to do] is recover the ship and that's our focus today, and we're not having any other conversations - to think about what might've been the case - until we have the facts on the table."
