Per Fox News:
Fox News political editor Joe Battenfeld then noted that Kerrys yacht, which he bought in March, had been spotted in Nantucket, Mass., where the senator summers with his wife Teresa Heinz. That would make Kerry liable for the sales tax.
He fully intended to pay the taxes - AFTER HE WAS CAUGHT CHEATING THE SYSTEM.
Boats move around, they're kinda cool like that. Just appearing, or even being temporarily berthed on Nantucket (or elsewhere in Mass) wouldn't trigger the tax.