Anthony Michael Baker was breath-tested after harbour staff noticed problems as his 40,000-tonne ship Shansi docked in the northern port of Marsden Point on Friday.
Baker was arrested and held in custody before appearing in Whangarei District Court where he pleaded guilty to breaching New Zealand's maritime law. He was fined NZ$3,000 (USD 2,222).
Baker's lawyer told the court the captain had been "suspended by his employer and it would be difficult for him to find work in a similar profession in future".
"The master is legally responsible for their ship and all on board, and must be able to carry out their duties safely," Rowarth said.
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"A shipping accident can have tragic and widespread consequences. It endangers the crew, seafarers on other ships, and the environment.
"Alcohol impairs judgment and increases the risk of accidents. Where we find seafarers over the limit, we will take action."
Baker, a 53-year-old from Devon, was not on duty when the 200-metre Singapore-flagged Shansi was due to berth, but was called to the bridge due to problems getting the engine underway and lifting anchor.
Police said Baker's reading was 1,345 micrograms of alcohol per litre of breath, well above the New Zealand limit of 250.
Northland regional harbourmaster Jim Lyle said before the hearing that police were called when the pilot assisting with the berthing "noticed that all was not okay and there was a problem that could affect the safety of the ship".