Noob torpedo firing question

[helibobber]

To many this will sound like a dumb question but here goes.
When I scoot ahead of my target and position myself to get a perfect 90 degree shot (or as close to that as I can) I come to a full stop at periscope depth. Now when I can just see my target coming into my range I want to turn towards him in a way so as to reduce my sonar size if tracking a DD. As he moves say from my left to right I want my boat to pivot so I can maintain a direct line to his midship in order to fire a torpedo.
Well, since I'm not moving how can I pivot my boat using the rudders if there is no forward movement on my part? If I go ahead slow and turn my rudder then I can pivot but I start moving towards my target and that is what I don't want to do.
I haven't learned yet how to fire my torpedoes manually and must rely on using the automatic targeting mode. I guess I just want to be able to control my boat more finely.
Am I making sense?

[GoldenRivet]

your rudders rely on water flowing past them in order to work.

if you are stopped... you rudders wont do anything for you.

the only way you can "pivot" as described would be to order ahead slow

[DanFraser]

Think backwards...

Or just reverse :)

[A Very Super Market]

Yeah, it's physically impossible to pivot on a point with a ship. Don't bother with a perfect 90 degree shot either, you don't need it.

[helibobber]

Think backwards...

Or just reverse :)

Ah ha! I'll try it.

[USAMP1980]

If by 90 degrees you mean perfectly perpendicular to the target... it does help a good deal with the "Impact" settings.

When you have the target locked in through your periscope.. click on "Ship:" , this will read off the "draft" of the ship. This is how deep the ship typically sets under water, and nearly the optimal setting for "Magnetic" setting. I would add a hair to the draft. about .2 meters in calm water. Of course, the faster a ship is going the more it will bob. Naturally, rough seas make settings hit-or-miss.

First half of war:
I have learned to never trust the intial electric torpedoes.. T2s I believe. They had issues with the detonator, as well as holding their set depths. I have seen them slowly fall as they head towards their target, falling too deep by meters.
The steam torpedo is much better for magnetic or impact detonation, particularly on "fast". Yes, they leave a bubble trail.. but the enemy will hear the torpedoes and you in their hydrophones anyways.. not to mention SONAR.

Usually, if you divide the draft measurement by two.. it will give you the best impact depth setting, depending on the shape of the hull. I use the minimum "1 meters" for impact on destroyers.
It takes 300 meters for the detonator to arm on "impact" setting, and 400m for "magnetic". Remember, that is the distance the torpedo must travel, not the distance from your scope to the enemy. It helps a great deal to already have your doors open ( "Q" ). I have had a great deal of luck firing at destroyers, etc when they are closing on me at 0 and 180 degrees with the "draft" and "magnetic" setting.

That may have been off topic, but it may help.
Yeap.. you have to be moving to turn the boat... give it 1/4 power atleast.