GERMAN SUBMARINES IN PARTICULAR. 119 



Practically all boats have clearing lines which are insulated and used for low 

 power wireless. These lines reeve from forward to the bridge and aft through a 

 sheave and back to the bridge, where they are fitted with turnbuckles and secured. 

 Some are secured aft, but all are fitted with turnbuckles. 



On a number of latest boats were noted an assortment of various sizes of ta- 

 pered wooden plugs to be used as shot-hole leak stoppers. 



The mattresses are stuffed with coarse horse-hair. 



The bunks for crew are of the hinged type — pipe rail bunks, with wire springs 

 with pipe bracket at the head end and are fitted with wire springs for pillow. Horse- 

 hair mattresses about 3 inches thick are 'nsLalled on the springs. The bunks are 

 usually 6 feet long by 23 inches wide. 



The aeroplane recognition signal on the forward superstructure deck is a sheet 

 metal ring hinged at the center and can be folded over double when not wanted. 

 The diameter is 6 feet 6 inches and the width of the sheet metal ring is 14 inches. 

 When open, the ring shows white throughout the circle, i. e., 14 inches white painted 

 circle. When closed or folded, the color is the same as the deck. 



Very little effort was made to camouflage the submarines, although a few 

 showed signs of having tried various designs — apparently up to whims of the com- 

 manding officer. The hulls were generally painted with light slate color and the 

 upper decks or "top side" with black asphaltum paint. A small number of gro- 

 tesque efforts a la Chinese junk style of eyes on the bow, etc., were noted. 



There were usually three external emergency air connections, consisting of two 

 lines each. These were located forward, amidships and aft in the superstructure. 

 The location is marked by a red cross painted near the lines. One line leads to the 

 compartments and one to the tanks. The air lines are i J^ inches outside diameter 

 and are closed by a butterfly cap which screws on the pipe over the outboard end. 



Each boat is fitted with two marker buoys — one forward and one aft in the 

 superstructure — which are released from inside the boat. These buoys are fitted 

 with ^-inch diameter wire cable. Most of them have no light and no telephone. 



The inner hull is built on a flush plating system with double-edge strips and 

 single, internal butt straps. 



The outer hull is sometimes built on a raised and sunken system but generally 

 with a flush exterior, obtained by joggling sunken plates, both edges and butts. 



Free flooding bow buoyancy tanks are installed in the superstructure — one or 

 two vents operable from the torpedo room or from the control room, or both. 



No housing guns are fitted. This practice was abandoned two years ago. 



The net cutter bow is knife edge or saw tooth, slanting up and aft at about 30 

 degrees from the stem-head, and is supported by steel bracket stays of "saw-horse" 

 design. The saw edges are hardened steel insert teeth or knives (10 or 12 of 

 them) about % inch wide, i inch to ij^ inches deep and 10 inches long, set be- 

 tween narrow steel holding plates. 



Vertical rudders, on some cruisers still building, are fitted above the hull to 

 assist in maneuvering submerged. They are like our G-4 installation. The upper 



