Which method do you use for your hydrophone checks?

[Diopos]

And to reply to Drakken:
My sonar practices are directly related to target availability. They're more relaxed when playing in a relative target rich situation (as I'm in now, playing stock 1.4, career mode, Nov/Dec 1943) and my general "scouting" is mostly based on long range radar sweeps and radio contacts. But when I "listen", in a low target density situation or want to avoid using radar, I usually do so for for 15-20 min going to a 40-50 m depth (avoiding to pass the thermal layer), engines stopped. In the begining and end of my listening period I always do the listening. I then surface and move to the next listening spot 10-15 miles away. That would be ~20min "listening" stops every 1-1.5 hour. Even in my radar based "scouting" routine, sonar is valuabale in the merchant/warship distinction of the target.

I heavily relly on sonar in convoy work. At present I try to enter and fire the torps from within the convoy taking shots from both bow and stern tubes (but take into account that I'm using auto_targeting, all other settings realistic, no cameras etc). This actually means lying in front of the convoy with its "middle" at 0 bearing.
So either by radio contact or by at least two long range radar observations I have a convoy route. I rush to my ambush area/point and place the sub verrtically so as to have the convoy coming generally at a 90 or 270 bearing. As soon as I have the convoy on sonar I go to periscope depth. I move and turn a bit as nessesary to keep the convoy on my 90 or 270 bearing. Take into account that I'm "listening" to the whole sonar signature of the convoy. So If I have the "outmost" contacts at 80 and 92 degrees I move ahead to obtain a more symmetric convoy "sonogramm" centerd at 90 degs. As the convoy approaches the convoy "sonogramm "becomes wider and you have specific contacts on the central and flanking escorts. Low speed, dive at 90m or at least below thermal and turn 90 degs to bring the convoy "sonogramm" at 0 bearing. Some adjustment maybe needed so this part of the manuver is better to be done before the convoy closes in. As the convoy approaches you observe the cental escort and the flanking ones. If you have the flanking escorts at ±45 degrees bearing (or more) it is time to get ready for the trip upwards. The signal is when the leading escort opasses over you and you "hear" it at your rear quadrant. Slow speed upwards turning to ±90degrees of your current heading maybe stopping the engines as you pass the thermal, pausing at 25m. "Listening" for merchants and extending the periscope mainly looking at your 90 degs trying to avoid a merchant ramming you. Then periscope depth and you know the drill from thereon. Your targets will be coming at favorable angles and ranges both from bow and stern (as long of course they haven't already rammed you:hmm: :hmm: )!!!!