In July 1976, less than a year after he had lost his parliamentary seat and cabinet post, he protested the visit of the 20,000 tonne American cruiser in his small yacht the "Dolphin". He impeded its entry to Auckland Harbour. The cruiser was forced to stop mid-stream to allow grappling hooks to be thrown to pull the "Dolphin" clear. Afterwards Amos was arrested and charged with obstruction. He was convicted, but the conviction was overturned on appeal by criminal defense lawyer David Lange. Amos' protest instantly became a headline-grabbing piece of political drama from which he took a lot of personal satisfaction at bringing public attention to the ant-nuclear issue. Lange would later become Prime Minister and passed a law banning the visit by nuclear propelled or armed ships with Amos' support.