The submarine, by very virtue of the qualities which make it a good submarine, is a poor boat for surface fighting. It can carry no very heavy armament, and it is not heavily armored. The problem of stowing away all the heavy machinery, supplies, torpedoes and devices necessary for her operations and maneuvering has presented about all the difficulties the constructors have been able to handle. The highest speed of the submarine is not in excess of 20 miles an hour. The submarine must be light and easy to handle. It gains in steadiness and certainty of operation with increased size, but it loses in capacity for quick and delicate maneuvering. In addition the submarine has what is termed a strategic vulnerability. A shot which might mean nothing more serious than a hole in the side to a surface boat would end the submarine's usefulness for underseas work and convert her into a helpless hulk of surface craft. The submarine is an easy quarry for a chaser, for even when submerged and moving along, the U-boat creates a distinct wave on the surface of the water which can be followed by the chaser. The little boats are just what their name implies--chasers--and besides having the qualities already described they may conceal themselves behind large steamers, and when the submarine in preparing to launch a torpedo makes its presence known the chaser may speed from its hiding place and drive the underseas craft away, even if it does not succeed in injuring it. OPERATING IN CONNECTION WITH AN AEROPLANE. The chasers also have a special facility of operation in connection with the aeroplane or seaplane, principally because of their high speed; and next to the chaser the aeroplane is one of the submarine's worst enemies. Used in conjunction with the regular torpedo boat destroyers of the navy, the chaser and the aeroplane promise in future wars to minimize the effectiveness of the underseas craft. This is proven by the fact that immediately after the United States naval forces joined those of the Allies in European waters, the disasters resultant upon submarine attacks were greatly reduced. The speedy destroyers, while not actually sinking many submarines, by their vigilance prevented the submarine from operating. Large types of the chasers ordered in this country by the Russian Government are 72 feet long by 11 feet 3 inches wide and draw 3 feet 3 inches of water. Each boat carries three of the 8-cylinder 6-3/4 x 7-3/4 Duesenberg, 350 to 400 horsepower motors. The boats carry an 18-inch torpedo tube amidships and a 47-millimetre rapid-fire gun on the forward deck. They are controlled from the bridge deck with a sheltered cabin for the quartermaster, with controls from either the shelter or bridge deck. They have a guaranteed speed of twenty-eight knots.