Boat Owners Association of The United States (BoatUS) is advising boaters with vessels that have a U.S. Coast Guard Certificate of Documentation to be wary of any letter arriving by U.S. mail offering renewal. BoatUS advises that while the Coast Guard does send official annual renewal notices by U.S. mail, other notices being received by BoatUS members are not from the Coast Guard but rather third-party companies whose name or return addresses may appear similar to that of the official…