Section 7.20 - Nantucket Sound, Vineyard Sound, Buzzards Bay, Narragansett Bay, MA, Block Island Sound and easterly entrance to Long Island Sound, NY(a) A line drawn from Chatham Light to latitude 41°36.1' N. longitude 69°51.1' W. (Pollack Rip Entrance Lighted Horn Buoy "PR"); thence to latitude 41°26.0' N. longitude 69°46.2' W. (Great Round Shoal Channel Lighted Buoy "2"); thence to Sankaty Head Light.(b) A line drawn from the westernmost extremity of Nantucket Island to the southwesternmost extremity of Wasque Point, Chappaquiddick Island.(c) A line drawn from Gay Head Light to Block Island Southeast Light; thence to Montauk Point Light on the easterly end of Long Island.