“B” Class.
(Completed 1904–6.)
B’s 1, 3, 4, 5, 6, 7, 8, 9, 10, 11.
These are submarines of the improved Holland type, and are in every way superior to their predecessors. They may be considered the first of the sea-going type. Their submerged displacement is 316 tons; length 135 feet, and beam 13 ½ feet. The motive power is the same as in the “A’s”—petrol for surface propulsion and electricity for use when submerged. The horse-power of the petrol engines is 600, and that of the electric engines 189. As in most submarines the supply of current for driving the electric engines is derived from storage batteries charged by dynamos driven from the petrol engines while the vessels are running on the surface. In the “B” class a special system of encasing these storage batteries was introduced. Their speed averages 12 knots on the surface and 8 knots when submerged. The surface cruising range is 1,300 knots at 10 knots per hour, and the maximum submerged endurance 80–100 knots at 5 knots per hour. Their armament consists of two bow tubes with 4–6 18-inch Whitehead torpedoes. Complement: Sixteen officers and men.
The “B” type are vessels about 50 per cent. larger than the “A” type which preceded them. The “B’s” have superstructures extending from the bow to the conning-tower, forming a narrow deck which tends to disperse the wave which heaped around the blunt noses of the “A’s” and original Hollands. Vision when submerged is obtained by two panoramic periscopes, each having an arc of vision of 60 degrees. In the more modern vessels three periscopes are fitted. The twin screws of the “B’s” are placed below the centre line of the vessel and consequently operate in deeper water when the vessels are cruising on the surface. This gives them better surface cruising qualities, as in a sea-way the propellers are liable to race if worked too near the surface. The increase in the speed of these vessels over that of the “A’s” was of great importance, as in this respect lies the weakness of the submarine. The tactical advantages derived from high speed in actual warfare cannot be over-estimated. The speed of a fleet is governed by that of its slowest unit.
The distinguishing feature of the “B” type is the straight bow, the forward superstructure, and the two periscopes. The B.2 was run down by the liner Amerika in the Straits of Dover in October, 1912, and was never recovered.