Research submarine: what happens on descent

I've talked to Nuke sailors who told me about tying a string across their berthing space while at the surface. As the sub descended the hull would be squeezed smaller and the string would droop. The men could tell whether they were very deep or shallow, by measuring how much droop they saw in the string.
I suppose if one of them knew how deep they were at various times, they could have set up a rough measurement gage, but the majority of the crew on Navy subs, didn't know where they were or how deep they were.

Some links:

http://www.pbs.org/wgbh/nova/subsecrets/

And a few on Life on a Submarine (in case you end up having to hunt through the stories or would find them useful).

http://americanhistory.si.edu/Subs/operating/aboard/index.html

http://www.dbfer.net/maindocs/boatlife/boatlife.html (Does have sound)

If you can't find it specifically with a search, look for Life on a Submarine. It may be a single sentence in a sailor's story (plus lots of other info).

By the way, several older submarines are available for tour. There's one in Hawaii and one in Wisconsin (or might be a bordering state). I believe there might be one in Connecticut, too.

I know an old bubblehead, I'll see if I can get him to comment.

I think the OP is talking about the little bitty research subs, like the ones they send down to poke around in shipwrecks, yeah? A submersible? Not the big kind that the navy uses?

I have seen a ton of documentaries about them, and they always talk about what it's like to descend (plus they do it on video!). When I was little I was really into Alvin (the research sub, not the chipmunk!).

http://www.whoi.edu/page.do?pid=8422 has a bunch of Alvin videos

And some stuff about other research submersibles, they're on the right and you can click on them: http://oceanexplorer.noaa.gov/technology/subs/subs.html

If you google HOV submersible or Alvin submersible you can find a bunch more stuff. I think there are only a handful of these thingies in the world, so you should be able to look up footage of all of them. I hope that helps.