How to target manually?

[SeaSpectre]

Greetings, everyone...

I am new to SH3 and I am (as I imagine all beginners do) using the automatic TDC with Weapons Officer assistance. Well, I have to admit that the missions seem WAAAAY too easy. All you have to do is get yourself out ahead of the target, submerge, wait until angle on the bow is zero and under 1000m and then when the triangle turns green, you shoot. I am, after just 12 patrols in my IIA, second on the list of all U-Boat aces with close to 70,000 tons already.

This is going to get boring pretty quickly, I think.

I would like to learn how to target manually, but the manual is of no help. Has anyone actually posted a "how-to" to teach total novices how to get range, speed, and heading values?

BTW, it also seems too easy to evade escorts/destroyers. All i do is go to ahead slow and drop the periscope. I don't even have to go any deeper than PD depth. Does it get more difficult to evade destroyers as the war progresses? I have slipped past destroyer screens and sunk numerous vessels in enemy harbors with little or no difficulty....

Looking for more of a challenge....