118 SUBMARINES IN GENERAL— 



of all late types is very heavy and plating is thick — i}i ^^ch to IyV inch (50 to 52j4 

 pounds). Where the conning-tower dome casting laps the conning-tower plating, 

 a thickness of 2^/2 inches to 2% inches exists, but this is only a lap; however, it is 

 probably from this that reports of "armor" arose. This plating is a special treat- 

 ment of bullet-proof steel. 



It is a general practice to fit fore-and-aft wood batten decks on the superstruc- 

 ture, following the superstructure contour including gun working circles. These 

 battens are about J^ inch to ^ inch thick, 4 inches wide, with Yz inch space between 

 battens. 



Hand-operating sounding machines are usually fitted in each type, generally 

 located in forward torpedo room in small types or on the third deck between the 

 battery compartment and torpedo compartment on the largest types. This machine 

 is similar to that used on surface craft so far as the principle of design is con- 

 cerned, but it has a special type of lead with a gauge in it. The machine is operated 

 through a tube casting (gland tube) through the hull, fitted with valves and stuff- 

 ing box to remove and insert the lead and for watertight purposes. On some ves- 

 sels the sounding machine is operated by an air motor. 



Recognition signal tubes for firing bombs from inside the boat are of recent 

 development and are found on very few boats. The design is quite like our own de- 

 sign and is operated on the same principles. These tubes are usualy located just 

 over the after torpedo room. 



All hydroplanes on the latest boats are of the "drowned" type, located well 

 down on the hull forward and aft. They are fixed planes and protected forward 

 by stream-line guards similar to propeller guards on destroyers. Aft they have a 

 half-guard on the after side and a wire rope guard forward or else a complete 

 stream-line guard, similar to forward installation. These guards cut down the sub- 

 merged and surface speeds very materially — the British claim about one knot for a 

 similar installation on British boats. Cruisers 139 to 142 are exceptions and have 

 above-water forward hydroplanes folding into non-watertight hull. They fold for- 

 ward and inward, overlapping each other in the stowed position. Guards are fitted 

 above and below the planes. The installation projects slightly beyond the hull lines 

 on either side when folded in. 



Two cast-steel or cast-iron pipe wireless masts of the hinged type are fitted. The 

 forward mast hinges aft and the after mast hinges forward in gutters in the super- 

 structure. Some are fitted with steps and a lookout station aloft^ — usually the for- 

 ward mast. The thickness of metal at the base is ^ inch. These masts are fitted at 

 the heel to a quadrant over which reeves a chain full which raises and lowers them ; 

 they are electrically operated from inside the boat. Each section of the mast is 

 swaged or welded together, each section being reduced in diameter from the deck 

 up. There is evidence of the use of acetylene welding in some sections and electric 

 welding in others. They vary in length from 28 feet to 54 feet ; average height 

 about 35 feet. It is understood that these masts were seldom used in any kind of a 

 heavy seaway, as it was dangerous to hoist masts or leave them hoisted. 



