A Customs Service plane has located the yacht carrying Norwegian adventurer Jarle Andhoy but there's been no response from those on board.
The explorer's lawyer has told Norwegian media that he is testing the vessel Nilaya in stormy conditions off New Zealand's coast to determine whether is capable of a trip to the Ross Sea.
The Customs Service says the vessel was outside its 24 nautical mile zone, though it is not saying exactly where.
Its plane circled the yacht numerous times on Thursday evening and received no response to several attempts to hail those on board.
Mr Andhoey's lawyer has told a news conference in Norway that the yacht has no emergency beacon because the adventurer does not want to put anyone else at risk if something goes wrong.
Last February, Mr Andhoey and another Norwegian, Samuel Massie, 18, travelled on the yacht Berserk to the Antarctic.
While the pair were attempting to reach the South Pole on quad bikes the Berserk disappeared in McMurdo Sound, along with the three men on board.
Mr Andhoey's lawyer says the adventurer is not planning another attempt on the South Pole, but wants to find out why the support yacht sank last year.