[Hitman]

Theroretically you needed in real life at least a dark, moonless night (Moonlight has no effect however in SH4 IIRC) if possible clouded. And then also needed was to keep a low profile (Bow points to target) and moderate speed (prevents phosphorescent bow wake).

So you would expect to be able to conduct those surface attacks under those conditions in the game, but if you don't, you can try to modify slightly the cfg file (it'sa simple text file) that regulates how much is the enemy AI crew affected by the darkness.