Slitherine

So, my carrier has been sneak attacked by a submarine. Being the careful type of guy that I am, I have two destroyers nearby, who proceed to ping and locate the sub. Unfortunately I don't kill it this turn.

Next turn I ping again with both - darn sub has moved away.

OR HAS IT?

Nope, it is right there still and within range of both pings, but just didn't show up.

How do I know this? When I moved my heavy cruiser accidentally into its hex, right next to the two destroyers.

So, be careful. Sonar does not always find the enemy (unless there's some ability I am totally unaware of like 'going deep').

Crashing into it always does though (which would make 'going deep' even more hillarious)

Yeah, I noticed this also.
But what is it?

I'm still not sure.

If a sub does not more or attack, it cannot be detected by sonar that turn.

Ah, it takes a couple of turns to reload torpedoes, so if it's target hasn't moved, it probably won't either...so undetectable.
koala, did the heavy cruiser damage the sub (such as ramming) or just reveal it?

adherbal wrote:If a sub does not more or attack, it cannot be detected by sonar that turn.

Thanks for the explanation adherbal!

Jagon wrote:Ah, it takes a couple of turns to reload torpedoes, so if it's target hasn't moved, it probably won't either...so undetectable.
koala, did the heavy cruiser damage the sub (such as ramming) or just reveal it?

It just reveals the sub. You can utilize this maneuver with a destroyer, who can attack the sub after accidentally uncovering it.
Other destroyers still can do nothing (which is kinda weird), as they cannot stuble into the same hex nor use their sonar - despite already knowing the subs position.
_____
rezaf

Hum the list of mechanics gets longer than you only stumble upon when reading the forum.

This is not good, it's not even in the loading screen hints or anywhere else.

adherbal wrote:If a sub does not more or attack, it cannot be detected by sonar that turn.

Yeah, true in theory, but it doesn't actually work. A more exact description would be that it cannot be 'uncovered' by sonar, but it can sure as heck be attacked if you can find it another way.

In the instance I quoted above, moving a naval unit into the submarine's hex will 'detect it' automatically even though it neither moved nor fired. The unit that detects it can shoot at it just like normal. Your other destroyer units can also shoot at it by using the sonar function as normal and then launching depth charges like a normal shoot.

Intuitively you would think the 'going silent' by a submarine would prevent it from being found/shot no matter what, but the dev's probably thought about it this way:
1. It is not possible to have two units occupy the same hex
2. They've obviously chosen that a two-unit clash results in the submarine being discovered (so as to not confuse the player by moving you to the 'wrong' target hex with no reason)
3. Once the submarine is discovered, it is fair game

So there is some point in a 'wall-like' screen of destroyers doing a sweep for submarines if you can guess well

I think a naval unit moving into a sub hex should be ambushed by the sub. A destroyer moving cannot use the sonar.
The ship should not be able to fire back and destroyers in the area would need to do a sonar sweep to establish the sub's location.
Subs are weak enough currently.