What Am I Doing Wrong?

Ok, so I know my first problem is getting out of my wonderful Alliance-class and hopping in a sub. The port crews looked at me funny as I climbed aboard. Course, that also could have been because I was a Royal Navy captian getting in a German sub. But, anyway, I was playing German sub mission 3, where you're supposed to shadow the American convoy and an RNE 'vette group shows up. Now, first thing I did when I noticed the RNE ships is shut my engines off. Not just stop the screws, turn the engines totally off. I also never got pinged by ASDIC, so I should have been completely undetectable to the RNE ships, and they could just do battle with the American escorts, and I'd pick up the leftovers if the RNE won the skirmish. At least, that was the plan...until one of the RNE Flowers made a pass right over me, dropped his cans right at my depth, which was 203 meters at the time (Germans make a pretty decent sub, it turns out) and sent me the very short distance to the bottom. My question is, how, in the name of anything you want to name, did he find me?!? Unless he's got the sonar guy from "Down Periscope" and heard the reflection of sound waves created by two fish humping off the side of my sub, I should have been literally invisible to him!! What could I possibly be doing wrong? I've got the difficulty set to the harder one, so it should be easier! This may be the final >;( in the long list that makes me give up on subs completely.

Ok, I'm done ranting...time for some begging...please please please can anyone help me?

1: The Orders...

Tail the convoy

2: Do so...

3: Tips:

Go to scope depth, flank ahead, keep up with the convoy, dont pay attention to the USN CV's and the ASDIC (thats from the USN CV's)

Use the scope plenty to make sure youre heading in the same direction as the convoy, and not being rammed

When the RNE CV's approaches the USN CV's will try to defend, with a little luck they sink 1 maybe 2 of the RNE's, but likely the RNE will sink all 3.

As you move along with convoy change direction now and then fire your aft tube to make the RNE evade (that will slow them down a bit)

Do NOT turn around and do NOT turn off your engines.

Keep following the convoy even that the RNE is pounding at them, use your aft to disturb them / perhaps get a direct hit now and then

4: The AI knows youre there just as you know they are there even with the engines OFF (sad but true, surface ships shouldnt see the indicator mark on the tac screen when a sub is "powered off").

Also remember that they know your last position, so they can calculate how far you can drift (its simple math, players can do that too if they takes the time to study the subs)

You are better off doing 1/3 or Flank to avoid them.

Hope this was a little help to you, I cant think straight right now, im burned out and going to bed...

Thanks for the advice, Jesper. Ran through it again just running from the RNE ships behind the convoy, and it went off with out a hitch. I'm still rather annoyed by the fact that the CV found me the first time, but oh well. I know the ships keep plots of your last known position, but I shouldn't have had a last known position since I never made a noise for them to find a position to begin with. Guess that's just one more thing to love about multiplayer when it comes out. Everyone plays by the same rules, since players aren't AI.