A pair of historical questions..

[Nisgeis]

If you want an account of a peace time US rescue, have a read of 'The Terrible Hours' by Peter Maas. It describes the sinking of the USS Squalus in 1939 (after the main induction valve didn't close properley during a dive) and the subsequent rescue attempts. It gives a good idea of all the problems involved in a rescue close to home, with ships available to help and the use of the distress buoys (which in war time were welded in place).

If you are on your own in the war zone, the procedure for escape also varies on the type of sub you are in and where you are on that sub. If you are in the rear torpedo room of a US sub, you have to unbolt the inner part of the escape hatch (the skirt), lower it down, turn it over and then bolt it back on again, to form a long tube which will hold air pressure in the escape hatch. You then flood the whole room at once and the tube allows an air gap to form, which you can use to breath whilst you fit your escape gear. Now try doing the same when you decide to wait for the destroyer that has just sunk you to leave the area, with a broken arm, no light except hand held lamps, the temperature rising due to escaping high pressure air (and possibly battery fire also) and with chlorine gas from the water that got into the battery making you choke or possibly rising carbon dioxide.

The forward torpedo room has an escape trunk, which you get a few men in, flood, open the door, get out, close the door, drain down (assuming you have high pressure air left) and repeat. It sounds quite quick, but in practice it took a very long time to complete. Each time you drain the trunk, the air pressure in the torpedo room rises making it hotter and more uncomfortable for the remaining survivors.

Once you have escaped, you have to ascend at the correct rate, so you can breathe out and in an equalise the air pressure in your lungs with the surrounding dropping sea pressure - ascend too fast, or hold your breath and you die. Then you find yourself on the surface with at the time limitted survival gear 300 miles from shore.

The escape is a pretty tricky thing to do with everything working perfectly and who knows what sort of damage things have taken - maybe the hatches no longer seal or won't open.

The USS Pampanito site has the following link regarding the escape procedue: http://www.maritime.org/tech/escape.htm and also on the Pampanito site there are some photos of the escape trunk with a handy virtual panoramic photo you can rotate and zoom in on.

HMS Thetis sank in 1939 in Liverpool bay and only four people escaped. The submarine had no damage (the sinking was caused by both ends of a forward torpedo tube being open at the same time) and she was in 140 feet of water. I think the stern was even sticking out of the water.

As for U-Boats being sunk, I am fairly sure I read that most attacks were pretty ineffectual, with depth charges being dropped on U-Boats caught on the surface doing little damage and the difficulty of hitting a target if it had already submerged. I think most sinkings of U-Boats came about when the homing air dropped torpedo was introduced, which was pretty much a one shot kill when dropped into the swirl caused by a recently submerged U-Boat. But that may not be the case as I don't have any stats to hand on the U-Boat sinkings.