BOSTON – Massachusetts Sen. John Kerry is docking his family's new $7 million yacht in neighboring Rhode Island, allowing him to avoid paying roughly $500,000 in taxes to the cash-strapped Bay State. If the "Isabel" were kept at the 2008 Democratic presidential nominee's summer vacation home on Nantucket, or in Boston Harbor near his city residence, he would be liable for $437,500 in one-time sales tax. He would also have to pay $70,000 in annual excise taxes. Rhode Island repealed those taxes in 1993. That has made the state something of a nautical tax haven.