The German Sonar installations in this type vessel consist only of the bare essentials necessary to operate a submarine. -- namely -- a listening equipment, an underwater telegraphy system and a fathometer.  
          The components of the installed equipments are mechanically and electrically well designed with the emphasis being on the mechanical design.  
          Echo ranging equipment was not installed nor are any of the equipments electrically connected with fire control circuits.  Bearing repeaters are not installed.  
          A voice tube provide the only means of communication between the Sound Room and the Conning Tower.  
          External shock mounting in form of bonded rubber mounts in compression, shear and tension are used thruout on inboard components.  
          The effectiveness with which the German submarine operated thruout the war is an indication that considerable ability was manifested by the German operating personnel.  
July, 1946
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A. Introduction
B. Descriptive
C. Conclusions
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  A.  Introduction  
          The scope of this report is to present in a general manner the systems installed and practices of installation.  
          Components of complete systems have been made available to Underwater Sound Laboratory, Fort Trumbull, New London, Conn., for bench testing and detailed exploitation.  In addition Underwater Sound Laboratory personnel have been operating with the German vessels, making field tests and comparisons with USN equipment installed in the German vessels for that purpose.  Two of these reports are available at present, others may be added to the list when they become available.  
          Those available are:  
                  (a)  NRL Memo C-471-657/45 dated 10 July 1945  
                  (b)  USL (interim) Report No. 47 dated 17 April 1946 by D.M. Sherwood.  
          In addition all late type sonar equipment used in the German Navy, surface and submarine, as well as a history of sonar in the German Navy is contained in detail in Nav Tech Report No. 530-45 dated 31 October 1945.  
          The following instruction books contain pictorial drawings, diagrams, and schematic diagrams of installed systems.  
          1.  Sonore UT-Anlage fur U-Boote (Sonar - Under-water Telegraphy System for submarines)  The above equipments manufactured by Atlas-Werke, Aktiengesellschaft.  
          2.  Beschreibung und Bedienungs - vorschrift einer Wasserschallsignal - Sende - Emfangsanlage.  (Description and Operating Instructions for a Water Wave Signal - Transmitting and receiving Systems)  The above is U.T. Sonar manufactured by "Electroacustic Werke.  It is essentially the same as that manufactured by "Atlas Werke"  
          3.  "Kabelplane" Cable plans for Electronic Installations and location of components.  
          4.  "Unterwasserschall - Gruppenhorchanlage"  (Under-water signal Group Listening System)  The above is manufactured by "Atlas Werke - Aktiengesellschaft"  
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  B.  Descriptive  
          The following systems are installed in this type vessel.  
                  (a)  Group Listening System (GHG)  
                  (b)  Underwater Telegraphy System (U.T.)  
                  (c)  Fathometer (Echolot)  
          A separate sound (not sonar) room is provided in which the following equipments were installed common to all vessels.  
                  (a)  G.H.G. Listening Equipment  
                  (b)  Radar Detection Units  
                  (c)  Shaft R.P.M. Indicators  
                  (d)  Gyro Repeater  
                  (e)  Voice tube connection  
                  (f)  Bench space for maintenance and writing.  
                  (g)  Rudder Angle Indicator  
                  (h)  A stool with spare parts stowage below the seat.  
          In addition to the above other electronic equipments are installed in the Sound Room presumably in accordance with the Captain's desires in that they vary from vessel to vessel.  Among those more commonly found in the Sound Room are the following:  
                  (a)  40 Watt Emergency Radio Transmitter  
                  (b) "Mae West" Transmitter  
                  (c)  General Announcing Control and Amplifier Panel.  
          The location of the components is covered in detail by reports and instruction books referenced in "Introduction".  
          Inspection of installations reveal the following practices which were common to all systems unless otherwise indicated.  
                  1.  Cables passing thru watertight bulkheads are grouped in the main cable banks and pass thru the community stuffing box.  
                  2.  Identification of cables and leads is kept to the bare minimum required by German practices.  See Report 2G-9C-S28 for detail discussion.  
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                  3.  A wide use of terminal boards thruout the systems similar to those described in report 2G-9C-S65.  
                  4.  All armor and shielding is thoroughly grounded at entrance points to components at the gland nuts of the tube terminals.  
                  5.  Strict attention to small design details which make for easy access, removal, and maintenance.  
                  6.  Physical grouping of related electrical components in common subassemblies which are electrically connected to other portions of the main assembly by means of plugs and jacks.  
                  7.  Designs which minimize the possibility of incorrect reassembly or replacement.  
                  8.  Controls and adjustments are kept to a minimum consistent with German practice in other electronic and electrical equipments.  
                  9.  Cables thru the pressure hull are usually of portable watertight construction.  The method of making the stranded individual conductor watertight is as follows.  Each conductor is made up of eight strands.  The center strand has applied to it a layer of rubber approximately 1/32" thick.  The other eight strands are spirally wound around this rubber covered center strand in such manner that they are embedded in the rubber so as to approach a solid cross section.  The individual conductor rubber is molded over the above assembly thus tending to fill all interstices with rubber.  These cables are usually two conductor.  The conductors as assembled above are twisted and a rubber outer sheath molded over them in such manner that a cross section of the cable appears solid.  
                  10.  Circular rubber packing of rectangular cross section is used in tube terminals and stuffing tubes thruout at cable entrances.  
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                  11.  Metallic gland nuts are used in all cases except where portable cables enter tube terminals, here phenolic gland nuts are used.  
                  12.  G.H.G. hydrophone leads are divided into two groups, one port and one starboard.  From a connection box in the forward torpedo room, each group of twenty-four portable cables is passed thru the hull.  The method for accomplishing this is as follows.  A relatively large hole os cut out of the pressure hull over which a suitable plate is welded.  This plate has presumably had the necessary stuffing tubes preassembled in the shop.  
                  13.  In addition to the watertight cable described under 9.  The German provides a backup feature as follows.  Where the portable cable enters a tube terminal a small 3 jaw steel clutch type clamp is assembled on the outer sheath of the cable, inserted in the tube terminal and then the rubber packing is assembled in the usual manner.  
                  14.  All inboard components of the systems are mounted on bonded rubber mounts in compression, shear and tension to provide for shock mounting and sound isolation.  
          In addition to the installed equipments provision for depth sounding in emergency is provided as follows.  In the Conning Tower six boxes of ten "Electroloten" are stowed.  This device is a small expendable bomb about six inches long and crudely streamlined with a considerable tail fin structure.  It was thrown overboard from the deck and would sink to the bottom at a constant known velocity.  It was arranged to explode on contact with the sea bottom.  The depth of the water is computed by measuring with a stop watch, the elapsed time from the moment when the bomb struck the water to the moment when the explosion was heard.  
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1. 110 Volt Regulated D.C. Power is obtained from the same voltage regulators that supply lighting power.
2. Motor Generator.
  Generator rating:
  6KVA P.F.  .80
  220 V
  50 Cycle
  1500 RPM
3. Motor Generator
  Generator Rating:
  1.5 KVA  P.F.    .80
  220 V
  50 Cycle
  1500 RPM
4. Motor Generator
  Generator Rating:
  .3 KVA
  220 V
  50 Cycle
  1500 RPM
5. T200FK39c Transmitter Motor Generator
  Generator Rating:
  .12 to .45 KVA
  1500 Volts D.C.
  400 Volts D.C.
  280 Volts A.C.   100 cycles/sec.
          The above motor generator sets and their associated controls are located in the Maneuvering Room.  Power for the motors is obtained in such manner that by making the proper external connections the sets will operate satisfactorily from voltages of 110-170 DC or from 220-340 D.C.  Dropping resistors are incorporated to make this possible.  
          The 220 V 50 Cycle and the regulated 110 V D.C. power supplies required for energizing the electronic equipment are fed into a common distribution panel.  From the above buses in the panel the individual circuits are run.  These circuits are fused only and are not provided with disconnect switches.  Fuses are accessible thru the front of the panel and are of the type described in Report 2G-9C-S62-2.  A nameplate is mounted to identify each set of fuses with the circuit energized.  
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  C.  Conclusions  
          It is not believed the German practices with regard to installation are superior to USN practices.  From inspection of circuit designs at the Shipyard, it would appear that USN designs are well in advance of German designs.  Final conclusions however, may be drawn when the reports of detailed exploitation by the Naval Research Laboratory become available.  The considerable thought given to space, ease of accessibility for replacement of parts for repair or maintenance, and, in certain equipments, the use of multipurpose tubes is noteworthy.  
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