Customs is asking that the crew of overseas vessels arriving at Port Taranaki carry evidence they have completed Covid-19 protocols and have health authority permission when they take shore leave.
The move follows incidents in New Plymouth where the crew of the Hong Kong registered Yangtze Flourish were confronted by port staff and reported to police while out shopping.
The Yangtze Flourish arrived in New Plymouth on 25 November with a cargo of palm kernel from Malaysia and its 22 crew were granted shore leave two days later after returning negative Covid-19 tests.
As RNZ reported last week, a district health board blunder meant the crew had not met the 14-day isolation period, but before that became publicly known, others had already taken it into their own hands to challenge their shore leave.
In a 1 December email, Central Ports chief customs officer, maritime, Megan Harvey, outlined the situation to shipping agents, the Taranaki District Health Board and Port Taranaki.
"The poor crew off the Yangtze Flourish have been getting a rather rough time since they were approved for shore leave last week.
"Last night stevedores and truck drivers prevented the crew from leaving the ship, and tonight they have had police called on them by a local supermarket who suspected they were breaching isolation."
Harvey said Customs was able to resolve the impasse at the supermarket quickly, but that the police had said the language barrier and proved difficult.
She sought a more permanent fix.
"I wonder if you could please consider asking the captain for any vessel that is granted shore leave, to print copies of the TDHB approval, so crew members can present these if challenged?
"I can understand the public's nervousness around this, but we want those that have met requirements, and are innocently going about their business, to feel comfortable about going ashore."
Harvey said having the paperwork handy could help de-escalate any issues.
Phoenix Shipping managing director Billy Preston, who handled the vessel's visit to Port Taranaki, said there were about 30 Customs officials monitoring the port as well as its own security staff - and there was no reason for anyone else to become involved.
"If a ship gets cleared and all the crew can go ashore then an email gets sent to the port, the port security and Customs, so everyone knows.
"But all of a sudden we've got stevedores and trucking companies that are deciding they want to be port security and prevent the crew from coming ashore."
Preston said the supermarket incident highlighted how maritime crew completing Covid-19 isolation were being treated differently than those arriving by plane.
"Say four or five Chinese guys come ashore and they're all wearing masks. And I guess they look out of place, you know.
"Whereas suppose you come through the airport you go your own separate ways. Within 14 days you've got your mask off and you can do whatever you like.
"I'd hate to think that that would be the way they would be thinking, but you can't help think there's some discrimination."
Preston was not a fan of Customs' solution.
"The suggestion is that they should be carrying a piece of paper with them to say they've been Covid cleared. Well if that's the case then maybe all New Zealanders should be carrying one."
Craig Harrison is the national secretary of the Maritime Union, which represents waterfront workers and seafarers.
He did not think anything sinister lay behind the New Plymouth incidents.
"For me I wouldn't call it discrimination. I just think there's a general nervousness by New Zealanders around the country that we could be exposed to the virus.
"And we've seen some border measures fail. Really I just think the New Zealand public need some assurance that things are working all right.
"But it seems to me that at the heart of it it's a communication problem saying that they've been tested, that they're clear and therefore they're not a threat."
What the public said
On the streets of New Plymouth people were willing to cut the sailors a break.
One man, Herman, was comfortable with the seafarers' presence in the city.
"I think we need to be careful not to dive into a sort of foreign danger mindset around this just because they're sailors."
Another, Russell, didn't see them as a particular problem either.
"Nah not really, as long as they've been tested before they get off. Like, they've been at sea for a couple of weeks, so that's long enough to know whether you've got it or not."
Port Taranaki declined to comment on the conduct of port workers in regard to the Yangtze Flourish.
And the district health board did not respond to questions about the merits of overseas crew carry copies of their shore leave approval with them.
Meanwhile, Maritime New Zealand said it was working with other agencies involved in the maritime border response to Covid-19 to address the importance of shore leave for seafarer welfare and remind the public of the strict criteria that must be met before it was granted.