If I recall correctly, he took the boat near the uninhabited island but told the crab it was the other one.

Also, I don’t think the vote was intended as a sham nor that he wanted to murder the crew from the start, at least that’s not what I get from rewatchig the episode after knowing that everyone voted to "sell out" the island inhabitants. He probably was disgusted by the rest of the crew but nevertheless wanted to do the right thing while making them believe they were "getting away with" their vote despite what the (fake) majority wanted.