Hardline marine activists Sea Shepherd have struck it rich, winning an $11.8 million gift that will help it build a new faster ship for its Southern Ocean whaling battles.

Dogged by slow vessels in the past, the purpose built patrol ship will be used for a future campaign in the Antarctic against the Japanese whaling fleet, Sea Shepherd said.

An impression of Sea Shepherd's new Southern Ocean patrol ship, designed by Dutch ship builder Damen.

The gift came in an annual disbursement by the Dutch Postcode Lottery, which awards around 50 per cent of its proceeds to charities.

"We are now able to proceed with the purchase of our dream ship and lift our conservation efforts to protect the Southern Ocean from illegal exploitation to the next level," said Alex Cornelissen, chief executive of Sea Shepherd Global.