The man believed to be behind two bogus mayday calls in less than a week, has cost taxpayers thousands of dollars and outraged his would-be rescuers.
On Monday, the Rescue Co-ordination Centre (RCCNZ) received a mayday call just before 6pm that the 17m vessel Pleasant Fisher was on fire off the coast of Oamaru.
Three adults and a child were reported to have abandoned ship and were adrift in a lifeboat 3km from the Waitaki River mouth.
A search of the area, which involved two helicopters, two fishing vessels and the South Canterbury coastguard, failed to find any trace of the vessel or a liferaft.
The search was suspended at 9.25pm, in the belief the call was a hoax.
Oamaru police are now investigating.
The caller was believed to be the same man who reported a vessel in trouble near Dunedin on Saturday.
However, no Search and Rescue (SAR) operation was launched because of doubts over the veracity of the call.
RCCNZ spokeswoman Sophie Hazelhurst said the centre was obliged to treat any distress calls as genuine.
While rare, hoax search and rescue operations were a huge waste of time and potentially dangerous, she said.
"If the call turns out to be a hoax, this can mean significant unnecessary cost to the taxpayer and can represent a huge waste of time for dedicated SAR personnel."
Monday's search involved police, coastguard, commercial fishermen, harbourmasters, helicopter operators and volunteers, "all of whom put significant time and effort into this search".
Dunedin marine search and rescue adviser Martin Balch said it was annoying a person would waste the time of SAR volunteers, and cause an operation expected to cost in the "thousands".
Mr Balch said he was "fairly certain" Saturday's mayday call was made north of Dunedin, while Monday's call came from the Oamaru area.
The hoaxer may not realise the calls he made on his marine handheld radio were recorded and available to authorities.
"While he didn't know too much the first time, he made a more credible story for the second."
Otago Helicopters managing director Graeme Gale said he was disappointed a person would go to such lengths to report a hoax mayday call.
At one point, the Otago Regional Rescue Helicopter chief pilot was in direct contact with the male mayday caller, who was able to accurately describe the sea conditions.
"They were saying all the right things."
Mr Gale said at the time he was focused on finding four people, including a child, adrift in a lifeboat, but was annoyed to later discover the call was a hoax.
"It is a low thing to do."
