The "Franklin D. Roosevelt" At Greenock. Ships Gather For Exercise "Mainbrace". A picture from the air of the United States Aircraft-carrier "Franklin D. Roosevelt", now at the "Tail of the Bend", at Greenock. The vessel,-of 45,000-tons, is one of over 160 ships of the navies of eight North Atlantic Treaty Organization countries which have gathered in the Forth and Clyde for the 13-day exercise "Mainbrace. It is the biggest gathering of warships in British waters or many years. Eight aircraft carries are included in the great fleet. September 11, 1952.