This is the classical "technical sim versus captain's game" problem.
Technically, US subs had no AUTOMATIC "fan mode". In U-Boats, as modelled in SH3, there was a "Fächerschaltung" which automatically sequenced the selected tubes.
In US Boats, each tube was fired individually and gyro angle had to be set for each tube.
However, this was NOT done by the captain, whose role the player takes.
The captain ordered a spread and said "commence firing" and the whole firing sequence was handled by the XO, the TDC officer and the guy on the firing button in the tower, and as a backup by the torpedomen.
So the only difference in firing fan shots was actually that the button-pusher (
) and the TDC operator (both tasks done by the same guy in a Type VII anyway) had a little less workload as he simply threw a switch where his US counterparts had to set a multitude of switches and fire each tube by stopwatch.
But for the captain, the firing procedure was the same. Problem is, this was verbally ordered and there was no buttons for it.