The 24-metre trimaran powerboat has special paint which deflects radar waves, meaning it can sneak up on Japanese whalers almost unseen in the Southern Ocean.
"It is like a stealth boat," said skipper Pete Bethune, who skippered Earthrace when it became the fastest powerboat to circumnavigate the globe by a powerboat last year.
The black carbon paint makes it virtually invisible to radar systems on other ships.
The boat has also been fitted with a broadband radar which can not be detected by other vessels.
Mr Bethune would not say if they would run without navigation lights in an attempt to get close to the Japanese whalers.
"You do what you have got to do." Earthrace was being bought by the Sea Shepherd Conservation Society and would join the society's ship, Steve Irwin, on a three-month mission in the Southern Ocean to protest at the Japanese whaling programme, he said.
The society would soon own the Earthrace and it would be used exclusively for marine conservation issues.
Mr Bethune said conditions in the Southern Ocean for the protest voyage would be "brutal" but Earthrace was a tough boat and well proven in heavy seas. It had had an additional 500kg of kevlar added to the hull beneath the waterline to strengthen it for possible contact with sea ice.
"It is a very dangerous place to go. The Sea Shepherd (Steve Irwin) will be leaving us for sustained periods to go back and refuel so we will be by ourselves down there except for the Japanese who won't be friends of ours. It will be a very tough gig.
"If we hit a big iceberg we are limping back to Australia, probably just 10 knots." Mr Bethune said he expected waves up to 12 metres high during the three day voyage to the Southern Ocean from Perth.
Earthrace would not follow Sea Shepherd tactics and try to ram Japanese whalers. Earlier this year the Steve Irwin hit a Japanese trawler as part of its protest action at whaling.
"We need different tactics. I can't tell you what they are. But we will stir things up down there. We are well resourced." Mr Bethune said his concern was for the safety of his crew and boat.
"We are going down there to mess with some Japanese who are extremely pissed off. They believe they have got a right to continue taking these whales and we believe they haven't.
"There will be significant conflict down there." He said he would be very surprised if the Japanese came to their aid if they needed it.
Earthrace is due to leave Auckland at the end of the month for Perth and will sail for the Southern Ocean on December 7.
The latest anti-whaling campaign will be launched on Friday with a public function at Auckland's waterfront.
