What does visibility dictate?

[Jonte]

What does visibility dictate? Is it just the range of spotting ships?

In that case, can't you change visibility to 8km and increase ships and convoys within the game so that the chance of spotting ships/convoys stays the same?

Or maybe you can have your lookout detect ships/convoys as far as 16km even if the visibility is only 8km?

I'm trying to figure out a somewhat realistic solution for people that don't want the performance loss that the 16km mod can cause...

[melnibonian]

In GWX your lookouts can see in clear conditions far more than the 8 or 16Km. If I remember correctly on a clear day you can spot a ship up to 25-30Km.

The visibility options in the game affect both U-Boats and ships, so if you're using the 16Km settings all the visibility settings in the game will double (both yours and the DDs)