There was a great deal of debate on the requirements for the new battleships. The design board drew up a number of proposals; one called for a ship with nine 16-inch (406 mm) guns in three triple turrets, 5.9 in-thick deck armor that would have made the ship immune to plunging fire out to 30,000 yards, and a top speed of at least 23 knots. The belt armor was a much more intractable problem; the 16-inch gun could penetrate 13.5 inches of plate, the thickest in an American battleship at the time, even at 25,000 yards. To proof the ship against her own armament—a characteristic known as "balanced armor"—the main belt would have to be increased to 15.5 inches, which would have increased the weight of the vessel to prohibitive levels. To mitigate this problem, sloped armor was proposed; it was infeasible to use inclined armor in an external belt, because it would compromise stability to a dangerous degree. Instead, an internal armor belt was constructed behind unarmored hull plates. This had serious drawbacks, however; it complicated the construction process, and if the armored belt was damaged, the external plating would have to be cut away first before the belt could be repaired.