The Defence Force is to help with efforts to enforce the country's Covid-19 border restrictions at sea.
Hundreds of foreign yachts have already been denied entry to the country, after wanting to escape the Pacific cyclone season.
They have been critical of New Zealand's stance, which was defended last week by Director-General of Health Dr Ashley Bloomfield.
Australia has taken a similar stance but was allowing applications for exemptions.
Bloomfield said claims by foreign yacht owners their uninsured vessels would be damaged in a cyclone did not constitute humanitarian grounds for their entry to New Zealand.
He added they had had months to prepare alternative arrangements.
The Ocean Cruising Clubs' roving rear commodore Guy Chester, who has been trying to get exemptions for the hundreds of yachties in the South Pacific, wrote to the government in April, seeking a solution.
"We were told by letter the end of June that there would be an exemption process on a compelling and humanitarian need. We waited until the end of July for the forms and the availability to be filled out for that. We were patient about that. And then on the website it said cyclone refuge is not a compelling reason."
The Defence Force said it was working with Customs officials to implement the Covid-19 public health response at the maritime borders.
A spokesperson said ships and aircraft would carry out surveillance patrols within New Zealand's economic zone and beyond into international waters, to be coordinated through the National Maritime Coordination Centre.
Defence personnel will also help Customs officers at ports around the country.
"The NZDF continues to play our part in the All of Government Covid-19 response while maintaining our normal responsibilities and operational commitments," the spokesperson said.