GIANT FLYING BOAT JOINS U.S. NAVY. The 70-ton Martin Mars, world's largest flying boat recently turned over to the U.S.

GIANT FLYING BOAT JOINS U.S. NAVY. The 70-ton Martin Mars, world's largest flying boat recently turned over to the U.S. Navy, prepares to take off on a test run. The ship, which can carry a cargo load of more than 15 tons, or 150 men, has flown non-stop more than 4,600 miles. It has a wing spread of 200 feet, and its two-deck hull has the cubic capacity of a 14-room house. Each of the ship's four engines develops more than 2,000 horsepower.