With the bouncing torps, another thing is make sure they're set to impact not magnetic if you're trying to hit the ship's hull directly. Use magnetic when you're trying NOT to hit the hull, usually aiming for the torp to run 1/2 to 1 meter under the target, to detonate directly under the keel. Kinda basic and you probably already know, but I didn't when I first started to play, so just thought I'd mention it. And again don't use a "glancing" blow, need to be really perpendicular impact. Don't "chase" a vessel if its too far ahead. or too far back coming towards you for that matter; you want the vessel's broadside facing you. And I think I read a post a couple of months back that said even with duds turned off, the game still will give you very occasional duds, more so towards the beginning of the war. The game just coded it that way into the early torpedoes I guess to accurately depict the real life early war torpedoes' unreliability.
A couple of threads about disabling fatigue, and also how to just make it more manageable. Check out this thread, about one third of the way down the page they talk about how to disable fatigue:
http://www.subsim.com/phpBB/viewtopi...isable+fatigue
Then check out this thread, the fourth reply down from "ReM" adds some further insight on how to disable fatigue:
http://www.subsim.com/phpBB/viewtopi...isable+fatigue
A little more on Destroyer evading. Because of their own engine noise, they're blind behind themselves. So once you see that they're aft end is pointing toward you, its a good time to speed up and change course, then go back to silent once they turn around a little to be able to hear you again. This will keep them guessing and it makes it difficult for them to plot where you'll be next.
Once they are in their depth charge attack run, go flank and turn sharply (using the "[" and "]" keys) to try and hurry up out of the falling depth charges path. The destroyer can't hear you anyway, since they're going flank also and the DC's start exploding, masking your noise. When they're going fast and DC's are exploding is the best time to run like a bat out of heck to anywhere but there. But remember to go silent again at once as soon as things quiet down, mind your stealth meter.
These things are a bit more tricky if there's more than one destroyer of course.
When you start to get pinged, turn to make sure your stern or bow is pointed toward the Destroyer, don't let your broadside face them- it gives their active sonar much more suface area to echo off of and find you.
Do a search on the topic of destroyers here at this forum and you'll find several posts/threads with lots more info than we can give you alone.
Here's a couple of the more recent threads:
http://www.subsim.com/phpBB/viewtopic.php?t=49454
http://www.subsim.com/phpBB/viewtopic.php?t=49623