He means this:
http://www.subsim.com/radioroom/show...0&postcount=42
That sub hull graphic is part of TDWs New UIs with TDC. Art2War has found you the link, install it as he suggests. When you lock a target in the periscope AND identify the ship in the manual TDC (don't know if it works with 'Crew Identify Target' command, I see no reason why not), the hull depth graphic will appear in the torpedo depth settings.
@OP - this question was also answered in your other thread.
