CONFIDENTIAL REPORT 2G-21
S12
     
 
FORMER GERMAN SUBMARINE TYPE XXI
 
 
 
 
HULL FITTINGS
 
 
 
 
SUMMARY
 
     
          The hull fittings exemplify the lengths to which the Germans went to eliminate sources of submerged turbulent flow on their later designs, and the degree of success with which they met their objective.  
          The fittings themselves, however, are not of essentially different character than those employed on earlier types of vessels.  
     
     
     
     
     
     
     
 
July, 1946
 
 
 
 
PORTSMOUTH NAVAL SHIPYARD, PORTSMOUTH, N. H.
 
     
     
     
 
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  REPORT 2G-21
S12
     
 
HULL FITTINGS
 
     
          Hull fittings consist of:  
          8 pairs of drop bits  
          2 towing chocks  
          Fittings for portable rail stanchions, although no stanchions or life line is fitted.  
          Portable anchor housing which was intended to be removed when ship was released for unrestricted operations.  
          Clearing lines which also serve as antennae  
          A towing hook, which can be released from inside the vessel  
          Deflectors for the submerged main engine exhaust.  
          A bullnose, plane guards, propeller guards or rudder guards are not fitted.  The stabilizer fins, however, serve as guards for the propeller and stern planes.  
          It will be noted that the effect of the foregoing is to eliminate all protuberances which might effect streamlined flow of water.  In this connection, it should be noted that the capstan head, which is the only unfair or unfaired item is removable.  
     
  COMMENTS:  
          The effort to eliminate all obstructions to free flow of water past the hull is apparent.  When the capstan head has been removed, the bits have been dropped down to deck level, and the inverted watch pocket which houses the anchor has been unbolted, the only extensions beyond the hull or above the deck are the faired stabilizers, the faired towing chocks, the engine exhaust deflecting plates and the clearing lines.  
     
  RECOMMENDATIONS:  
          The vessel demonstrates what can be accomplished to eliminate many minor sources of turbulent flow when submerged.  
     
 
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