CONFIDENTIAL REPORT 2G-21
S48-9
     
 
FORMER GERMAN SUBMARINE TYPE XXI
 
 
 
 
SOUNDING TUBES AND VENTS
 
     
 
SUMMARY
  
     
          Sounding tubes and venting arrangements continue to be normal in general, but the installation of sounding tubes in drinking water tanks is retained from earlier types of vessels, and one pair of main ballast tanks is provided with inboard vents for use after blowing in order to offset overcompensation.  
     
     
     
     
     
     
     
 
July, 1946
 
 
 
 
PORTSMOUTH NAVAL SHIPYARD, PORTSMOUTH, N. H.
 
     
     
     
 
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  REPORT 2G-21
S48-9
     
          Sounding and venting connections in this type of vessel are as follows:  
 
 
Sounding
Sounding & Vent
Sounding & Drain
Vent
After room bilge
X
Maneuvering bilge
X
Bilgewater tank
X
Eng. room bilge
X
Battery Wells
X
Sanitary tanks
X
X
Provision locker No. 3
X
Trim tanks
X
WRT tanks
X
F.O. collecting tank
X
X
L.O. tanks
X
X
L.O. gravity tanks
X
Drinking water tanks
X
X
Wash water tanks
X
X
Wash gravity tank
X
Hydr. oil collecting tanks
X
Torpedo tubes
X
Poppet valve tanks
X
 
     
          Inboard vents, with sight glasses and mufflers, are fitted to the regulating tank, regulating bunker and MBT 3.  Inboard vents are provided as well on all fuel oil tanks and a further inboard vent is provided for the spray shield over the torpedo tube nozzles.  
          Vents are provided at the high points in fluid piping systems.  
          Main vents are discussed in the S29 and S49 sections of the report.  
     
  Comments:  
          Applications are normal in all respects.  Much greater use is made, in this type of vessel, of separate sounding and venting tubes than in earlier vessels.  The provisions of inboard vents on MBT 3 is unusual, and is explained in the General Information book as being installed to permit reventing after blowing when submerged, without showing a bubble on the surface.  In the absence of any pressure gauges or other indication of the condition of this tank, it is thought that the arrangement would be of limited value except in an emergency.  
     
 
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