Why bother attacking convoys???

[Tinman764]

The active sonar had me scratching my head tonight aswell.
Had just made my 2nd attack of the night on a large convoy and was quietly slipping away at 2knts 80m deep backtracking down the convoys route. I had 2 escorts chasing shadows 1500m away and was just letting the tail end escort pass over me when he started pinging me. I did nothing to alert him, wasn't reloading etc, so how he knew I was there is a mystery - his 1st round of DCs where bloody close aswell.
2 RL hours later, and I was able to surface and bring in my external stores ready for round 3

[Iranon]

To the 'why bother?' question: That's why ships sailed in convoy, to deter or at least fare better against submarine attacks.
Germany tried hard to get some large commerce raiders into action to take advantage of this - even the RN didn't have the resources to protect most convoys against a battleship.

[Tessa]

Originally Posted by Tinman764

The active sonar had me scratching my head tonight aswell.
Had just made my 2nd attack of the night on a large convoy and was quietly slipping away at 2knts 80m deep backtracking down the convoys route. I had 2 escorts chasing shadows 1500m away and was just letting the tail end escort pass over me when he started pinging me. I did nothing to alert him, wasn't reloading etc, so how he knew I was there is a mystery - his 1st round of DCs where bloody close aswell.
2 RL hours later, and I was able to surface and bring in my external stores ready for round 3

For true silent speed you need to be going around 1 knot, in the command room look at the engine rpm's; once they hit 50 keep the engines at that speed and you'll be (more or less) invisible to their passive sonar. Have had them frequently pass right over me but unable to get a solid contact (and weren't using active sonar) makes for a pretty easy escape.