I have found Mittlewaechter brilliant tutorial extermely helpful in conducting submerged attacks. His method works so well I rarely need to use the periscope. He has a great little training video that shows exactly what to do.
Here's the links from a pervious but related discussing here at subsim.
http://www.subsim.com/radioroom/showthread.php?t=136323
Here is the link Mittlewaechter included that points to his dicussion on the Ubi boards.
http://forums.ubi.com/eve/forums/a/t...945#8301008945