Thanks, DrMilton & mheil for your nice comments.

You can change your course slightly for a better attack position without determining a new AOB. As your boat turns, the new bearing is reflected in the TDC's computation; thus turning the boat (changing course) acts the same way to the TDC as turning the periscope/uzo.

For instance, you've established the AOB to course intercept and have loaded it into the TDC along with target speed. You know that you want to have a torpedo run of approximately 8oo meters, so you've manually put that into the TDC. But as the target approaches some 2000 meters away, you're on too steep an angle for a 90 degree hit. So, slowly turn (5 degree rudder) toward a more perpendicular angle to target's course as it approaches. There is no need to change any information in the TDC. With this attack position, you're so close that any minor change in true AOB would be minimal. Torpedo Los! when the distance and angle are optimum.

It's possible I can't understand something because of poor English skill, but it seems to me that what you wrote is not true. It's almost everyday for me to set my TDC long before final approach to my target _before_ changing my course by 90 degrees. I set the TDC like I was on the position to shoot, then I turn my bow to the target and shoot the torpedo (I always remember NOT to lock my UZO/scope on the target while turning; in fact I almost never lock anyway). So if the TDC was affected by turning my ship, my settings would fail to work. But they work, so my opinion is turning the boat doesn't affect the TDC settings.

Of course it would work other way if I had my UZO locked on target all the time, that's obvious.

You are absolutely correct, turning the boat does not affect the previously set TDC settings. The periscope/uzo does not need to be lock just as long as you aim at the target before you fire. Don't forget to open the outer doors first!