[speed150mph]

As others have mentioned, ships and subs have very different procedures to classify, with ships being easier since you have more options and the generally make more noise.

Determining surface vs sub contact is fairly easy unless at very long range. Listen on broadband, turn on sound and use the mark 1 ear drum. If you hear a loud hissing sound, it's generally going to be a surface ship, if it's making a quiet thrumming bass sound, that is most likely a submerged contact. And if it's making a buzzing whinny sound, that's a torpedo and it's time to run like hell. Now I'll break down what I do with each.

Surface contact

First thing I do I quickly guage distance (how loud the noise is) and type of ship (most in game cargo ships will make a distinctly different noise then a fast screw ship like a powerboat or a warship) I use that to prioritize what contacts to focus on and determine if they may be an immediate threat. If they are, try to take evasive maneuvers to avoid detection and get some space.

Assuming they arnt an immediate threat I turn so my sub is positioned so the contact is between 30-60 degrees off my bow. This allows me to point my bow, hull, and towed array at him while keeping as small a sonar profile as possible in case he goes active. Try and acquire him on all three arrays to triangulate his position faster and with better accuracy. This also allows you to get a better ID passively as the different sensors tend to pick up different frequencys. I get a preliminary ID and then if he's distant enough to now worry me I go to periscope depth.

At periscope depth I start off with my ESM antenna. This will get you a quick ID unless their running emcon conditions. If that's the case I raise periscope and try to grab a picture. Do this stuff quick as your easier to pick up in the surface duct and periscope make good targets.

I look at all the data I have, try and classify. If I can't identify then I slowly creep closer until I can.

Then you do your TMA if you know how, or you wait until the auto crew gets it right (ie the solution speed matches the demon display speed, bearing matches, range looks about right) once your confident it's correct, feel free to engage.

Submerged contact.

With a submerged contact it's a lot harder. Start off the same way as with the ship. Put him 30-60 degrees off the bow, and try and triangulate him with your sensors. Try to get an ID with narrowband frequencies.

If there is a layer, purpous over and under the layer. This will tell you if he is above or below the layer and give you a depth range.

Once you match the ID, get a solid solution. Then engage.

Hope that helps some