120 SUBMARINES IN GENERAL— 



section of the rudder is on the same shaft as the lower section. This practice is not 

 standard even on cruisers. 



B. — Of the relatively more important features the following points may be 

 briefly mentioned :■ — 



(a) ,Conning-tower control. 



(b) Complete double system (supply and exhaust) ventilation. 



(c) No broadside tubes. One or two stern tubes. 



(d) Very large heavy conning-towers — of nickel steel when nickel is available. 



(e) Bulkhead doors in pressure bulkheads are round and very strong. 



(/) Double hull affords much protection from damage especially by depth 

 charges. 



(g) Hull strongly built but very wide frame spacing. 



(h) Heavy concave-convex pressure bulkheads in U, UE. and UB. types. 



(i) Latest UB. boats have control room fitted with pressure bulkheads. 



(;') Auxiliaries — all electrically driven. 



(k) "Drowned" bow hydroplanes except in U-140 class. 



(/) Chariot bridges fitted in all types. 



(m) Superstructure deck fitted with a superabundance of ammunition lockers. 



(w) Many gun emplacements (two to four) but usually only one gtm mounted 

 except in cruisers and Deutschland class. 



(0) Time of diving reduced by "Twin Kingstons." 



(p) Kingston valve control scattered throughout the boat. 



(q) Tanks controlled by vent domes and their valves controlled by shafting 

 led into control room. 



(r) Control of boat in all its operations is divided between conning-tower and 

 control room. 



(s) Navigation, torpedoes, etc., controlled from conning-tower. Diving, tanks, 

 etc., controlled from control room. 



(t) All periscopes motor operated. House in steel tubes which extend to keel 

 in some cases. Housing distances 12 feet to 14 feet. 



(u) After periscope houses in a steel tube or well large enough to take a plat- 

 form and man up and down. 



(v) Other periscopes only usable at full extension. 



(zv) Third periscope offset from C.L. with eyepieces in control room. Houses 

 in steel tube, forward and to starboard of conning-tower. Usually have a large, 

 heavy f airwater casting. Very rugged and heavy. 



(x) Head sections of all periscopes very small, some going down to i inch; 

 the latter not believed to be satisfactory. Reported unsatisfactory. Ten feet hori- 

 zontal base range finder in cruisers. 



(y) Special periscope attachment permitting fixed seat in conning-tower and 

 yet see through at all heights, thus doing away with platform. This is only on a 

 few of latest boats. 



(^) Galley is electric — electric cookers used, not electric range. 



