What you could do is play a single mission with the game realism seting turned down.
Here you can watch on map view how far each ship can see (gray circle on map). You can watch this circle change as you adjust your speed, turn towards target (lower profile) etc. It is a good way to then guess how far they can see.
Then try again at night
This can also be done with antisub ships. Their sensors can be shown on map and you can see how much noise you are making at depth etc. (orange and red circles).
If you are deep and at silent running - watch the orange circle around the dd increase if you load a torp, increase speed etc