[PavelKirilovich]

Schwuppes: A merchantman isn't going to detect the pinging, only warships equipped with hydrophones can hear the ping over shipboard noise and alert others.

I've had exactly one success with the radar. Night, no moon, and overcast. Because there's no way to make it any darker on the sea's surface than that, really. Thanks, mother nature. Seas are pretty calm, wind 5m/s, so I leave the Radar on. We make a contact ~25km away. I increase speed to ahead full. We intercept. I make a surface attack from a range of one kilometer, relying primarily on radar data and a stomachful of carrots to dimly make out the outline of the C2 merchantman. One torpedo later (Amidships, keel) and she's on the bottom.

The RWR (Radar Warning Reciever) has saved my life so many times I cannot begin to count. Generally speaking, if you get an RWR contact, your Funker/RADAR operator will shout out "Recieving Radar Signals!" At that point you crashdive immediately. I find a good tactic in shallow water is to hit C, then P. In other words, order a crashdive, then immediately thereafter periscope depth. You'll slip beneath the waves decently fast but in Stock at least, won't open the vents to the point that you're bound to hit 70m before you level off.

You'll have time to determine aircraft bearings using reference on the navmap, and approximate range that they acquired you at.

It is CRUCIAL to keep the RWR as late-generation as possible, according to your renown. This is because the Allies will update their RADAR sets to operate on different wavelengths, and if you cannot detect a centimetric wavelength, and they're using a centimetric set to track you, you are not going to know it until it's almost too late to evade.