I'm sure night battles have been suggested before, but it would be possible to attach some interesting mechanics to them.
Mainly would be different. Seeing as night times are dark (so you can't see), ships used lamps and lights to allow their crews to function properly. You could have a system whereby a commander can turn their ships lights on/off to avoid being detected. However, as I mentioned before, you can't see at night so to balance the massive gain in stealth to turning off your lights, armament reloads could be reduced by 20-40% to simulate the fact no-one can see what they are doing. Obviously, firing your guns makes alot of light so the spotting range for firing would stay the same.
Firing from smoke and around islands could be changed as well. When a ships fires, a broad marker could be displayed to ships nearby (within the normal visibility whilst firing range of the subject ship) indicating where a ship has fired from, similar to the current indicator for radio location. This would only last for a couple of seconds so as not to be too OP. Alternatively, the model of a ship could be displayed without a name, health bar or icon, and not appearing on the map. I know that sounds OP (it is) so I'd suggest having that model appear somewhere in the vicinity of the ship firing. This could give players an indication where and what the ship is, or the model could be altered randomly to another ship with similar turret layouts, to increase the mystery. For example an Izumo model could be swapped for a Nelson model.
That's pretty much all the thinking i've done on this subject, and i encourage people to add ideas and suggestions.
