The Master and Second Officer of the cargo vessel Rena were sentenced on a total of 11 charges laid by Maritime New Zealand (MNZ) following an investigation into the ship's grounding on the Astrolabe Reef off Tauranga on 5 October.
MNZ laid six charges against the Master, Mauro Balomaga, and five charges against the Second Officer, Leonil Relon, following the grounding. Both men pleaded guilty to all charges against them.
The two men were each sentenced to seven months imprisonment on Friday.
The Director of MNZ, Keith Manch, said the two senior officers, who were responsible for the navigation of the ship, had breached basic principles of safe navigation.
After a passage plan for the journey from Napier to Tauranga had been prepared, the Master had given approval for the Second Officer to deviate from the plan to make good time.
These alterations were not adequately recorded or an amended passage plan developed. Neither were the alterations verified using appropriate navigational methods.
Dangers to navigation, such as reefs, safe passing distances and adjustments to navigational equipment were not identified and highlighted.
The final alteration to the course of the ship, around 1.35am, put Rena directly on target to hit the Astrolabe Reef. No further steps were taken to project Rena's position forward along the new course, or estimate where the alteration would take the ship.
About 10 minutes before the grounding, the Astrolabe Reef appeared as an echo on Rena's radar. At this stage, there was sufficient time to make an effective alteration of course and avoid the reef.
The Master saw the echo and assumed it was a small vessel - however, after looking for the vessel and not finding it, he dismissed it as a false echo.
When Rena ran aground, at 2.14am, the impact left the bow section stuck fast on the reef, and sheered about 60 metres of keel away from the bow section of the ship, which began taking on water.
Mr Manch said the Master and Second Officer had failed to implement and follow basic principles of passage planning to ensure the safe navigation of the vessel.
"In this case, the Master and the Second Officer have breached the most basic fundamental principles of safe navigation. If there is a need to deviate from a prepared passage plan, the alterations must be plotted and the new projected path carefully assessed to ensure all potential navigational hazards are identified."
Mr Manch said during the course of the MNZ investigation, both officers admitted making alterations after the grounding to the ship's GPS log, its passage plan and its computer to mislead investigating authorities.
"This offending is also very serious in that it caused genuine confusion for investigators trying to piece together the events that led to the grounding.
"It is vital that when these types of events do take place, we can find out how and why they have happened to help prevent such an event happening again."
Mr Manch said MNZ welcomed the sentencing, which held the two officers to account for their failures in relation to the incident.
"This grounding has had significant consequences for the Bay of Plenty community and the country as a whole. Today marks a milestone in the response, which is still underway."
Mr Manch said MNZ was supported in the investigation by the Bay of Plenty Regional Council, Police and other parties, including the Port of Tauranga, local Iwi and the local community.
In a separate prosecution, MNZ has also laid a charge under the RMA against the owner of Rena, Daina Shipping Co. The case was today adjourned without plea until 18 July.