Has anyone been attacked by an undetected enemy?
 

So as I was sinking yet another Russian sub with my Dads old boat, HMS Sceptre (god bless you modders!) I was thinking about how each mission is basically a race to detect the enemy and launch an attach without being detected.

I've never once had to deal with being attacked by an undetected enemy. Has anyone been in this situation?

Yes I have. What you see is a suddenly apprearing torpedo heading towards you. A quiet running diesel sub can easily get a TMA solution on you when you see nothing on the map, especially when you are heading in the wrong direction for your sonar to detect him.
Other higher-value subs like Victors, Sierra etc. are currently easier to detect.

Anti-sub patrols are the most difficult in CW currently. You need the right tactic, or you go to bottom fast...
One error not to do is e.g. when you have the advantage being in the baffles of an enemy sub, then don't increase too much speed to catch up, because you won't see the torpedos fired at you until it's too late. I got sunk several times by doing so, not taking it seriously enough.

I had modded subs on both sides, one of the missions I was running, apparently the game called one of those subs, which had "sped up" torpedoes... and a little more difficult to detect, sinking what I thought was the last boat in the mission, I didn't event hear/see the torp coming... lol

AI doesn't actually do countershot right now so you're pretty safe torpedoing someone as soon as you make them. Sometimes I even launch one speculatively as it makes the subs bolt.

That is, as soon as they get TIW you get your get out of jail free card.

Try to switch to Realistic or Elite in the difficulty, also I think the 2004 Campaign I'm currently playing has tweaked it to a harder difficulty, subs will definitly fire as soon as they detect you. You also need more than 1 torpedo to score a sink on the bigger subs (and ships). Also sing time acceleration is dangerous...
But yes: there should be more snapshots from them.

Yup subs will definitively counter fire when they hear a launch on realistic.

I've got a pretty good tactic now when the situation allows to fire from above the enemy sub and then dive deep. 9 times out of 10 the reaction shot from the enemy will be on at the depth you fired from.

Absolutely, especially in the 68 campaign. Noisy surface conditions don't help either. Factor in having been dumped into battle at flank speed by an unexpected map-mode contact that doesn't actually appear once you're "dropped in"... There's been more than one occasion I've been scratching my head searching for a contact only to find it via a launch against me. Quick-fire off a counter at the launch and go into evasion mode is all you can really do...

I have. Was hunting a Spetsnaz insertion off Norway in the 86 campaign. Came into contact and was tracking a nuke boat and had the diesel insertion boat fire on me.

I did take note of the launch transients bearing and headed over there to have a listen. Found the diesel boat and sunk it. He somehow lost me during my race to get out of the torps activation/search window.

I have. Usually results in their death. Sometimes I do use active sonar to scare them into panic firing then send a present down their bearing. If that scares them into trying to run at flank, then they are certainly dead.