Al, one of the neat things about SHIII is that many of the parameters of the game can be changed in the .cfg files. you can view these using notepad and tweak the numbers. However, if you look in the mod forum, you can find very simple mods that let you adjust these things while backing up originals and not majorly screwing anything up. You can tweak all kinds of stuff!
you wouldn't believe what happens if you set your submerged speed to 100 knots, patricularly if you are firing torpedoes that only go 30 kts...
Let's just say, Bernard ensues.