Howdy Bill,
I was sure I had a couple shots from my visit, but they ain't in with the others! Anyway, found this:
Some quick Torpedo Lingo:
(apologies if I'm telling you stuff you know)DOOR
A torp tube has two "DOORS," breech (loading) and muzzle (shooting). The muzzle door is properly called "OUTER DOOR". When closed, the tube is watertight.
In the movies "flood tubes 1 through 3 and open outer doors" means let the water in and then open the muzzle hatches/doors - you can't open the muzzle door until flooded, as sea pressure is too strong.
SHUTTER
This is the strip of metal that conforms to the hull when closed, for hydrodynamics so the boat doesn't drag (and also make noise) ramming into the water. It is NOT water tight, just part of the bow to keep water flowing. So a LOT of gaps! And big ones.
The Type IXs had a system almost identical to the US Gato subs:
The IXs had the shutter slide forward OUTside the hull, the Gatos INside, but otherwise, same principle.
Here's the VII system: (attached)
The Type VIIs had a complicated connection between the shutter and the outer door - the outer door was hidden behind the shutter.