Since this topic has been revived it got me thinking if I could find any photo's of a real ww2 American submarine's gauges. I did some searching and found this.
Warning! Large picture!
http://thestandardedition.files.word...3/img_1543.jpg
I think the one on the top left would be the depth gauge since it has that red hand at 300. Probably test depth. It's only marked to 400 but it should be able to keep spinning around until it couldn't take the pressure and it explodes.
Edit: Here's a smaller pic
