[I'm goin' down]

I recommend you move to 1.5. Activate the Easy Aob mod, SCAF and Max Optics mods, too. That will assist you in getting a good firing solution where the 'X" on the Attack Map coincides or is close to sitting atop the target's silouette. You can restore the silouettes with EZ Plot 1.0 if you cannot see them for some reason. SH1.5 Gold Edition is selling on Amazon for around $13.

If the line emanating from the "X" on the Attack Map is not adherig to the target's course (even if the "X" is initially centered on the target), either the target course setting using the Aob dial is incorrect or the target has changed course. If the target's course, speed and range/aspect ratio are entered correcly on the stadimeter (dial on the upper right of the periscope screen), your sub can alter its speed or course and it will not affect the firing solution because the target's course is being tracked by computer (i.e. the TD.)

Hitman's Manual Targeting at 100 Percent Realism is a tutorial which walk you through the steps of setting up a good manual targeting solution. I can be downloaded in the Popular Mods sticky by Neal Stevens which is located in the mod forum. The Easy Aob mod is a must for quick manual targeting using the TDC, as it helps set the target's course correctly.