The troubled Interisland ferry Aratere has barely returned to sailing Cook Strait, but will soon be out of action for two days for an annual check-up.
A survey for Maritime New Zealand will check the ship's systems including lifeboats, sprinkler systems, smoke and fire detectors.
A complete in-water hull inspection will also take place.
"Many of the checks to be carried out require the ship to be stationary, without any passengers or vehicles on board," said Interislander General Manager Thomas Davis.
"This includes a full test of the firefighting system on the rail and vehicle decks.''
"All the ship's systems need to be fully operational for a survey, meaning she couldn't be fully surveyed while in dry dock."
Aratere resumed passenger sailings across Cook Strait last week, eight months after losing a propeller on November 5 last year.
It spent three months in Singapore having a major overhaul.
In-water surveys are a regular part of a ship's safety schedule, similar to a car's Warrant of Fitness.
Aratere's final return sailing will be her 11:20pm departure from Wellington on Saturday. It should return to service at 2pm on Tuesday.
All freight and passengers will be taken on sailings made by Kaitaki and Arahura.
Interislander's other vessels were also due for surveys and maintenance soon.
Kaitaki will undergo a scheduled maintenance layby next month, and Arahura was scheduled for an out-of-water survey and mainteance checks in September.
"It's good to get all the vessels surveyed and signed off ahead of the peak freight season, which begins to build in September and runs through until Christmas. We take safety extremely seriously, and we're looking forward to having Aratere signed off and back sailing on Tuesday," Davis said.
- The Dominion Post