Ship main cannons should not be able to damage submerged units

[Levitybot]

Describe the bug Currently a Battleship's main weapon can be ground targeted and the blast damages quickly destroys submerged units like submarines. Not only is the very unrealistic as the subs would be far under water, it also largely removes the point of having subs in the game if they can be damaged by main cannons and very easily destroyed. This exploit removes the value of submarines and a large amount of naval strategy from the game.

To Reproduce

1. Build a Battleship
2. Wait for your enemy to approach thinking their subs are safely submerged deep underwater
3. Ground target their submerged units as if they were just sitting at the surface

Expected behavior It should not be possible to damage a submarine 100's of meters under water with a main cannon. It's not even realistic they would be able to shoot down. Submerged units should not receive damage from main cannons.

Screenshots If applicable, add screenshots to help explain your problem.

Additional context For it to be realistic that a Battleship's main cannon is so powerful it can travel through 100's of meters of water to damage a sub it would need to be powerful enough to 1 hit kill every other unit in the game at surface level. This totally unrealistic exploit ruins naval battles, by massively reducing the value of ever building submarines. Submarines should have and were intended to have a major strategic role. This exploit should be addressed to make subs and naval strategy part of the game.

This bug report will be read by people that have not experienced the bug themselves - this report is all they have to investigate. The more precise your report, the easier it becomes for us to help you.

[Garanas]

This has been extensively discussed on the forums, see also:

• https://forum.faforever.com/topic/845/battleships-shouldn-t-be-able-to-damage-submarines-with-artillery-fire
• https://forum.faforever.com/topic/3041/countering-seraphim-t3-submarine-hunters

And there is one large other topic that I can't find. There is a solution available, drafted together with @Spikey84 in https://github.com/FAForever/fa/pull/4094 where the damage is reduced the deeper a unit is. Note that it is never completely removed, at most to 50% in that PR.

This is a balance discussion, so I'll tag as and ping @Tagada14 to give his view

[Tagada14]

Will be discussed in the next Balance call

[Tagada14]

This is intentional and the game is currently balanced around this mechanic. It's very unlikely that it will be changed in the near future.