''Small Pacific nations are not equipped to safely berth or dry-store this number of yachts, and any that do remain in the region will lose the safety net of their insurance,'' she said.
Even if New Zealand did offer exemptions for cyclone refuge, time was running out, because the application process took four weeks, with another week or so for visa processing.
About 70 per cent of international boaties make Ōpua their first port of call in New Zealand.
Far North Holdings, which operates Ōpua's marina and quarantine facilities, said it could handle the influx as long as arrivals were staggered. General manager Chris Galbraith said about 30 quarantined vessels could fit comfortably along the inside of the marina's floating attenuator. If the outside was used as well that number could be raised to 50.
''The key thing is that they (health officials) make a decision soon, because we don't them coming down in one big group," he said.
"Weather windows come along every 7-10 days, and if they miss one they have to wait for the next one. The later the decision, the more likely the yachts will arrive in one big burst. We want a early decision so we can control the flow and manage the risk.''
Once in isolation boaties in Ōpua would have access to water and contactless deliveries of food. They would have no contact with land, and CCTV would show if anyone tried to sneak out.
When crews arrived they had effectively already been in isolation for an extended period, because the passage from Fiji took 8-12, days and from French Polynesia about 20, Galbraith said.
In a normal year about 470 of the 600 international yachts arriving in New Zealand cleared Customs and biosecurity in Ōpua. Many of the rest headed to Marsden Cove, where marina manager Brent Wilson said four berths were currently set aside for quarantine.
However, that could be quickly ramped up to 12 by installing fences and portable gates. So far three fully Kiwi-crewed vessels had waited out their isolation at Marsden Cove.
The Health Ministry didn't respond to 'Northern Advocate' queries, but its website says foreign yachts are barred from entering New Zealand unless they have an exemption granted on humanitarian grounds, which would be unlikely to include situations relating solely to financial loss, or to vessels travelling primarily for pleasure or convenience.
Boaties could have other compelling reasons for travelling to New Zealand, but that would have to be demonstrated to get an exemption.
If the 300-odd vessels are allowed to enter New Zealand, another issue is where they would go. Many marinas are already short of space due to yachties riding out the pandemic in New Zealand instead of taking the traditional trip up to the islands at the start of winter.
Whangārei Marina manager Brian Caulton said there wasn't much space at the Town Basin.
''A lot of (overseas boaties) have been here all winter, and last summer as well. But we're picking that a lot of them are going to do some sailing in New Zealand, and that will free up capacity," he said.
In any case, some vessels would need maintenance, and others would opt to drop anchor down the coast.
Northland Medical Officer of Health Dr Catherine Jackson told a recent DHB meeting that the same rules applied for people arriving by sea as by air. Only New Zealanders or foreign nationals granted exemptions could enter, and all had to provide a negative Covid test and undergo isolation. The difference was that boaties could stay on their vessels instead of going to a managed isolation facility, and there were nuances in the quarantine period for people who had been at sea a long time.
Public health nurses, Customs and MPI staff went out by boat to meet incoming vessels, which had to give advance notice of arrival or face a fine of up to $15,000.
So far the number of yachts arriving in Northland was less than one a week, usually with two or three people aboard.
If quarantine facilities at Ōpua and Marsden Cove were full, she added, yachties would be directed to wait or continue to Auckland.
According to the World Health Organisation, Fiji has largely dodged Covid-19, with only three new cases since mid-July and 31 since the pandemic began. French Polynesia, however, has recorded as many as 51 new cases a day since reopening its borders for tourism last month.
The territory had 720 cases as of earlier this week.
