whelp. brain gave me a small muddy stream today. wasn't even cutting through the woods, just like along someone else's patio.
posting the results here anyways.
in underwater combat, I think part of the thrill should be trying not to be discovered, hiding in the murky depths.
so!
sonar, because it's cool. watsonian reason is that regular LoS in battletech is done through a mech's sensors and not actually line of sight. the distances are too big and the targets too small for poor human eyes to see. Aquatic combat is a more intense version where even standard or even clan sensors (adjusted to air) have a difficult time.
First idea: hard LoS cap. let's say 15 hexes out, you have no LoS. don't matter if you have a gun that goes further, a remote sensor, a spotter( ok maybe a spotter is ok(?)) you can't see.
this means that if you don't want to fight at knife ranges, you need some sort of dedicated detection system.
The idea here is you could select different equipment for your mech with their own dedicated ways of bypassing the water hard cap or as a requirement for water exclusive weapon systems.
Like a sentry pulse version, extending in a straight, blockable, line forward, that you can activate at the end of that mech's movement. if something crosses that line, that mech has LoS on whoever passes. or something that just activates during the tag phase?
Heavy torpedo version where you can fire/place a non-damaging sonar pulse generator in a distant hex.
passive sonar systems that detect jumping/swimming units or other actions.
c3i but earlier and for water.
self guiding torps that will find their own targets but might miss or tract to a different target.
surface boat giving telemetry.
maybe the clans have a little drone that does the same.