Half of the navy's in-shore patrol vessels will not be in use over the next 12 months, but the Government insists a lack of staff is not the reason.
One of the four vessels will be on "reduced activity" because of a reallocation of staff and another will undergo maintenance, leaving only two of the vessels, which are used in border security, fully operational.
The "reduced activity" comes amid the Government's call for the Defence Force to find more than $350 million in annual savings by 2015, mainly through back-office cuts.
Defence Minister Jonathan Coleman told One News there would be two boats doing "the job we need".
"But at the moment we just haven't got the people available to do the crewing on the third boat, because they will be ... taking annual leave [and] taking the opportunity to get some continuing education."
Defence had earlier said switching more than 300 uniformed staff to civilian roles had a greater impact than expected, but a spokesman for Mr Coleman said those roles were basically re-established as civilian ones.
"[Defence] nominated around 400 jobs across the defence force ... They're all non-deployable back-office jobs as opposed to jobs on a ship ... [and] they replaced them with people who aren't in uniform."
"All those jobs have just about been replaced by civilians," he said.
The four vessels, which have been in operation since 2009, assist in maintaining border security alongside the police, the Department of Conservation, Fisheries and Customs.
Resignations from Defence are at a record high, rising from 112 and 105 in November and December respectively, to 204 in January, One News reported.