JAPAN has asked Australia to prevent the Sea Shepherd ship Steve Irwin leaving port to harass its whalers in the Antarctic next summer, but the plea may have little effect.

The anti-whaling activists plan to upgrade their fleet from an ageing, former North Atlantic fisheries patrol boat to include another ship - something out of the future. The global speedboat Earthrace would head south under Sea Shepherd colours next summer, the group's leader Paul Watson said.

Looking more like a giant spider ... the activists' new Earthrace, which last year circled the globe in 61 days, fuelled by biodiesel.

"It looks like a spaceship. It can do 40 knots and dive under waves completely. We'll be using it to intercept and block harpoons."

In 61 days last year Earthrace circled the globe fuelled by biodiesel. The New Zealand owner/skipper, Pete Bethune, said he decided to become involved because "this is happening in my backyard and it really pisses me off. I'm going to make a stand."