TDC and realistic playing

[Radio]

Atm I am playing the game (with my own megamod-soup) on nthe hardest settings, meaning no mapupdate, no targeting assistents etc. and I realized one thing:

The TDC is rather useless! The way one usually plays (with autopdate etc) the game gives you way too precise target data, however if you are using your own position marks and try to find the data yourself the TDC becomes virtually useless.

Why?

-During the day you will not be able to use the periscope w/o being detected.
-During the night you will not see the target good enough to get useful data
-If the weather is good your periscope is easier to see
-If the weather is bad it will ruin your target gathering procedures

This changed my way of getting target data and attacking completely.
The radar becomes the sensor of choice, followed by the active sonar, the later being restricted to targets w/o hydrophones, meaning that every warship and most late-war merchants can hear you etc.

It also slows down the attack speed, whereas you can normally (with map-updates) can use the 3 minute-rule to get target speed and course I now use a 30 minute rule with the radar.

It basically boils down to RockinRobbins/Dick O#Kane methods with some guestimating and more manoeuvering during th final attack phase.

I can simply not see a way to use the TDC here in a practical manner.

What are your observations, do you have better ideas for the TDC "problem"? Or do you agree to my observation?