A tall ship is set to visit ports on the lower Penobscot River to mark the country’s 250th anniversary this summer. The schooner Harvey Gamage, a training vessel built in South Bristol and launched in 1973, will come to Bucksport for four days and visit Bangor, Brewer and Castine between July 29 and Aug. 3. It may be joined by other historic and educational vessels throughout the course of the “4PortLoop” event organized by the Penobscot Maritim…