Hi Gentlemen,
while looking for the photo of the uncovered periscope well, among the other photos from HMS Graph I have found some worth of interests.
13.jpg - the vent of the (I'm not sure) MBT3 or saddle tanks starboard. In the VOZM book, it is described as MBT 3 vent.
16.jpg - the vent valve lever of the MBT 3 port
10.jpg, 11.jpg - there are visible two handles for operating the flood valves (kingstons) of the MBT 3. As we know, there were 3 pairs of the flood valves. These handles are inserted into the slots for the forward two pairs (see the picture "flood valves.jpg").
21.jpg - this photo presents the charging the U-Boat HP air flaks (or less likely the oxygen flask). This photo is quite similar to the photo published in the VOMZ book, but is taken under quite different angle, so more interior of the magnetic compass casing is visible. What is interesting here, are the visible handles of the emergency blowing manifold. You can clearly see the handles with thickening for easier recognition by divers (see the picture "emergency blowing manifold.jpg").
Don, I think you have to revise picture on the page 218 in your Skizzenbuch and move the ovals, which marks the location of the emergency blowing manifold to the magnetic compass casing.
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Regards
Maciek