Access arrangements are generally well thought out, but the physical detail are not unusual, and in certain cases are rather definitely objectionable.  No further research is indicated.  
March, 1946
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C  O  N  F  I  D  E  N  T  I  A  L
          A water-tight door is provided in each of the four pressure bulkheads.  The door assembly consists of a cast frame fitted and riveted to the dished bulkhead, and a circular cast door with a square section rubber gasket.  The door is secured by means of a rotating geared locking ring on the periphery of the door frame.  The ring is provided with lugs which, when the ring is rotated by turning a pinion by means of a crank on either side of the bulkhead, engage wedge surfaces on the door and compress the gasket on a flat seat.  The door is further designed to prevent movement of the locking ring when the door is open, and the door hinges are so designed as to give free play when dogging the door.  The operation and the mechanism is almost identical with that on the breech door of a USN submarine torpedo tube.  The clear opening is 800 mm (31.5") in diameter.  Corrosion-resisting material is not employed.  
          Hinged doors in the light water-tight bulkheads are provided with 6 dogs and have a clear opening of 1450 x 850 (4'9" x 20.6").  Lower doors are of wood or metal, depending on location, and all have a clear opening of 1450 x 450 (4'4" x 17'7").  
          Pressure hatches are provided as follows:  
                  After torpedo room (access & torpedo)  
                  Engine Room (access)  
                  Conning tower upper and lower (access)  
                  Galley (access)  
                  Forward torpedo room (access & torpedo)  
          The clear opening diameter of the torpedo hatches is 660 mm (26").  That of the other hatches is 600 mm (23.6").  The dished radius for torpedo hatches if 850 mm (33.4"), for all other hatches except the upper conning tower hatch is 555 mm (21.8").  In this last case the thickness of the hatch cover is increased 50%.  
          All hatches are fitted with counter springs, latches, worm drives for three dogs, and dovetail section gaskets.  The seats of the hatches on certain vessels examined are  
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  brass strips screwed to the tops of the hatch trunks.  
          The principle on which the hatches operate is the same as that in use in the U.S. Navy.  The scantlings of the mechanism check closely with those in current use, the gasket is unsatisfactory, and the seat assembly where brass strips are used offers unnecessary possibilities for leaks.  
          Rectangular hatches 500 x 500 (19.7" x 19.7") give access from the control room to magazine No. 1, from the walking flat to each battery at two locations, and from the galley to magazine No. 2.  These are light portable affairs, fitted flush, with a waterway around the bottom of the opening.  
          Manholes are provided to give access to each tankage compartment, pressure tank and interior tank.  All are bolted, with a clear opening of 300 x 400 mm (11.8" x 15.7").  Compensating rings are provided in the case of manholes in pressure tanks, and cover material is 18 mm (.71").  Elsewhere the covers run from 5 to 8 mm (.20" x .31"), depending on the working pressure of the individual tank.  
          Ladders, all of which are portable, provide access from below to the hatches listed above.  Aluminum or brass tubing and bar stock is used in their assembly.  Of interest is the fact that the upper end and lower conning tower hatch ladders are directly over one another, that the lower ladder is at an angle of greater than 90°, and that both are provided with hand rails.  
          Ladders and grabs topside are provided as necessary, pipe or round bar stock being used as appropriate.  Grabs are also provided in tanks, below manholes, wherever necessary.  
          The engine room, lower conning tower and galley hatches are fitted with skirts for use as escape hatches.  Further, the conning tower is fitted with a plate extending downward from the overhead aft of the hatch, in order to trap a bubble of air.  Although means for escape are provided as shown above, there is only one lung charging manifold, which is located in the control room.  The conning tower is not arranged for use as an air lock.  
          Apparently considerable thought has been given to the matter of access.  Hatches and doors are made as large as possible, and are provided, where necessary, with grabs to  
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  facilitate swinging through instead of climbing through.  Ladders are arranged to provide easy access, and hand rails, overhead grabs and similar fittings aid in rapid descent both from the bridge to the control room and from the bridge to the deck guns.  
          It is regretted that the manholes do not carry through the same thought, for they are at best a tight squeeze for a middle-aged person, and are frequently so located with respect to adjacent machinery that the clear width given above is not fully available.  
          The hatch design is less than satisfactory, as the dogging, gasketing and seating are such as to leave their performance under depth charging open to question.  
          The pressure-tight door mechanism, employing ordinary steel as it does, is believed to introduce an unnecessary hazard unless great care is taken in its maintenance.  Personnel on board, however, have given favorable report of its performance.  
          There is nothing novel in the access arrangements provided, and further study is not believed indicated.  
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