There is a problem with the stadimeter, it currently gives inconsistent readings and is therefore pretty much useless. I also presume it is reading the wrong info, therefore garbage in= garbage out. Hopefully, that will be fixed in a patch.
In the meantime, you can download Arclight's excellent accurate periscope mod and determine range as the real
Kaleuns did. I have tested it and if used properly, in conjonction with the enhanced recognition manual, it will give you accurate range readings all the time.
Arclight's periscope mod:
http://www.subsim.com/radioroom/showthread.php?t=165408
enhanced recognition manual:
http://www.subsim.com/radioroom/show...gnition+manual