Subject. . . . . . . . . Operation "Primrose".
From. . . . . . . . . . Engineer Officer, H.M.S.Bulldog.
Date. . . . . . . . . . . 11th May, 1941.
To. . . . . . . . . . . . Commanding Officer, H.M.S. Bulldog.
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Submitted:  
 
     
                  On boarding "Primrose" I considered the object of my visit was.  
                          1.  To ascertain her sea worthiness.  
                          2.  To stop the Port Motor which was going "Ahead".  
     
                  It was ascertained that the Pressure Hull was intact and that there was negligible quantity of water in the bilges.  
     
                  "Primrose" was down by the stern with approximately a 150 list to port.  
                  A slight bubbling noise was heard outside the Pressure Hull on the Port side of the Motor Room which was the After Compartment.  This bubbling noise was considered to be air leakage through a Tank vent Valve being watertight, or the outer Shell of The Flooding Tank leaking, it being presumed that this damage having been sustained during the action.  
                  "Primrose" was considered sea-worthy provided the suspected flooding of a Port Tank was not rapid or the Tank too large.  
     
                  My attention was next directed to the Port Motor, which was turning at between 30 & 40 R.P.M.  
                  What was presumed to be the Central Rheostat was operated & put in Off position, (Pointer turned anticlockwise till no further movement was possible), & the speed of the shaft reduced to 15 R.P.M., the shaft continued to move at this speed with a reading of 10 Amperes on the Meter indicated in Red on the attached rough sketch.  
                  The rheostat was moved in the opposite direction, causing an increase of Motor speed.  The Rheostat being then turned to the Off Position.  
     
                  The switch in No.1 in sketch was then placed in Mid Position the shaft continuing to turn, but the rheostat when operated would not increase the Motor Speed.  
     
                  The Switches No.1,2,3,4, & 5, were now all in the same position on both Port & Starboard Switchboards.  
 
                  The Rheostat at the After end of the Port switch board was next examined and found to be in the Off Position, it was turned two  
 
 
 
 

 

 
 

   
Operation "Primrose".    (continued)                            Part 2.
 
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  notches, & a loud ticking noise followed.  
                  A booby trap being suspected the necessary avoiding action was taken.  
                  The switch board was then examined for any differences in the switch positions but none were observed.  
     
                  Word was now passed that a submarine was suspected in the vicinity of "Primrose".  I therefore proceeded to the Upper Conning Tower having closed all watertight doors and hatches on the way.  
                  Later returning to the Control Room I collected several books paper etc, which I placed in a Brief case which already contained personal effects.  
     
                  Charts were next observed to have considerable markings on them, so instructions were given to have them passed up & placed in the boat.  
                  The Conning Tower Hatches were then closed & I rejoined the remainder of the boarding party.  
     
                  It seemed that "Primrose" was now a little more down by the stern & a signal to this effect was passed.  
     
                  On "Primrose" being secured for towing, I returned to Bulldog with the boarding party.  
     
 
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                  The following is a statement of my recollection of the Main Engines & Motors.  
     
                Main Engines.  Very clean design.  Totally enclosed, (no pipes or valves being visible.
                                  No flywheel visible.  Shaft appeared to come Aft through a flywheel casing, which may have been a Hydraulic Coupling as no "Dog Clutch" was visible.  
                                  Shaft brake fitted just forward of After Engine Room Bulkhead.  
                                  As far as I remember the Engine was a 9 Cylinder Engine, and that there was a date stamp on the forward End of the Main Starboard Engine of 1940.  
     
 
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                  Main Switch Board.  Cream Vitreous Enamel Flush Type Board (Switch actuating leavers only penetrating the board) with Flush Mounted Meters, Filet & indicating Lamps.  
                                  The general layout of Switch board being as follows.  
                                  Port Main Switchboard had two circular Rheostat  
     
     

 

 
 

   
Operation "Primrose".    (continued)                            Part 3.
 
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  Handwheels, mounted vertically on the forward end of the board working in parallel & connected at the back of the switchboard as no mechanical connection was visible.  
                                  What appeared Two Small Selector switch handles, mounted vertically at about 12" centres, presumably for volt & Ampere meters.  
     
 
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                                  The next Group of fittings Aft of these mentioned were a row of indicator Lamp Windows below which were grouped Volt & Ampere meters.  
                                  At the Mid board position was a group of small fittings the Nature of which cannot be remembered, but below which was a meter with what seemed to be Cross Pointers (The Right Hand Pointer indicating the Left Hand Markings and vica versa)  
                                  On the left of the Mid board position were so far as is remembered several small fitments & at the after end of the board a small Rheostat with some smaller fittings above, perhaps Volt & Ampere meters & indicator Lamp windows.  
     
 
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                                  Mounted below the previously mentioned fittings were several insulated bars which presumably carried or operated Main switches.  
                                  So far as I can remember they were in the following order.  
     
 
1. . . . . . . . . Three Position Switch. (Ahead, stop & astern Position?).
2. . . . . . . . . Two position Switch.  (Battery Switch?).
3. . . . . . . . .    "         "           "        (    "          "       ).
4. . . . . . . . .    "         "           "        (    "          "       ).
 
     
 
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                                Switches 3 & 4 were locked together by a rod which moved For & Aft through the handles & held in place by a locking screw on the locking rod.
     
 
5. . . . . . . . . Large Switch.  (Main Switch).
6. . . . . . . . .     "         "    .  (Charging Switch 1).
 
     
 
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                  The submarine seemed well appointed & I noticed the floor Plates were of a Polished Material with Rubber Matting fitted on top.  
                  A 3" shell had hit the Conning Tower within a few inches of the Starbd Side Light.  The shell had exploded but had done very much less damage than I had expected to find.  
                  So far as I was able to observe all electric lights were still burning.  
                  I did not open the W/T Door in the After Bulkhead as this compartment was known to be dry, & it was considered safer to have second W/T Bulkhead intact in case the Aftermost compartment should flood.  
     
 
 

 

 
 

   
Operation "Primrose".    (continued)                            Part 4.
 
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                  While carrying out investigations, ships in company carried out several attacks which proved very distracting, especially when making or breaking circuits on the switchboards.  
                  The Foremost Periscope was raised some four feet & trained slightly abaft the Port beam.  
     
     
                                                                                                    
                                                                                             Lieut Cmdr. (E).  R.N.R.  
     
                                                                                                 Engineer Officer.  
     
     
     
     
     
     
     
     
     
 
     
     
     
     
 
 
 
 

 

 
 

   
MOST SECRET.
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From. . . . . . . . . . The Commander (D), 3rd Escort Group.
Date. . . . . . . . . . . 14th May, 1941.    I/52.
To. . . . . . . . . . . . The Captain (D), Greenock. .
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Subject. . . . . . . . . Observations made onboard submarine U 110.
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Submitted:  
 
     
                  The following details were observed by Sig.W.Marchant and by Tel.A.Long H.M.S.Bulldog while rescuing gear from U 110 on 9th May, 1941.  
     
  Signaling Equipment.  
     
                  There was one very small battery signaling lamp and a slightly larger battery lamp, otherwise no means of signaling by flashing was carried.  A pair of hand flags was observed.  
  2.             A double barrelled Verey's pistol with colored cartridges was stowed in the control room.  
  3.             There was no type of V.C., V.F., or other recognition lights.  
     
  W/T Equipment.  
     
                  In the W/T office were two H.F. transmitters very small and compact, run off the 220 volt supply.  
  5.             There were two receivers, one a servicetype Telefunken set and the other a civil broadcasting receiver.  
  6.             There were two short aerials from the conning tower.  
  7.             There was no sign of an R.D.F. set or an ordinary D/F set.  
     
     
                                                                            
                                                                                  Commander.  (D)