More than a dozen schooners are setting sail off Maine for a friendly race from Islesboro to Rockland. The Maine Windjammer Association’s 37 annual Great Schooner Race starts at 11 a.m. Friday off Islesboro, with the boats expected to arrive in Rockland by mid-afternoon. Fifteen or more schooners are expected for the race. The informal competition celebrates the days of yore when cargo-laden schooners out of Maine would race to market to get the best prices for their load. The race is touted as the largest annual gathering of traditional schooners in America. On Saturday and Sunday, members of the Maine Windjammer Association will host free tours of their schooners from 2 p.m. to 4 p.m. each day at Rockland’s North End Shipyard and at Windjammer Wharf.