If you're playing without any map contacts at all and aren't in a situation where you can ping your target, you're either going to have to estimate the range based on radar readings on the A-scope (I also believe there's a mod out there that will let the radar report ranges) or you're going to have to close to visual range and manually get range reports from the stadimeter. Just check the bearing of the target on your radar/periscope, note its estimated distance (either on the A-scope or on the TDC after getting a stadimeter reading), go to your map, and put a mark at the correct range on the correct bearing. There may be a better way of doing things, but this is how I would do it.

If you use this method, you're going to have to make a lot of marks before you can get an accurate course estimation. If you're chasing a task force like I was in the video, you'd probably end up sitting well off of its course while making your readings, letting it pass you by, then doing an end-around to get in front of it again and make your attack.

Yes i know its complicated and i like it.
well thx to you very much you very helpfull!!

its not even 2nd week of my carear its end of 1941 and i have no radar btw what ods fixes those problemes with radar, reports etc?
and i have some issues, chech Borneo thread in here.

what mod makes "ship identification" task of XO and its fast and realiable? I have team, of officers, helmsman and etc, its strange if i do all job "alone"

There's no real problems with the radar. You don't have it yet because it is not available in 1941. It won't become available until mid-1942. As for the mod that will have the radar report range, I'm not sure, I just remember seeing it.

The ship identification is part of Trigger Maru Overhauled. TMO makes sweeping changes to the entire gameplay experience. You can find it here:
http://www.subsim.com/radioroom/showthread.php?t=132330

very nice.
 

They have a word for captain's like you. It is "ACE." You are ready to instruct at the War College.

Pshaw. I knew nothing when I picked up this game two years ago, just careful study and practice. It took me about five takes to get the video like I wanted it...some of the bad takes were technical issues, but on one at least I forgot to set the speed on the TDC when I activated it for the battleship, and sent my torpedoes harmlessly astern of it...NARF.