I added something to the OP about that, Visual radius is 12 MS, RADAR x2, SONAR x3 (although for Subs its x4). Aerospace 20+8 for each Altitude above 1 with similar x2 RADAR.
Energy can only shoot at what it can see as energy doesn't arc. I think this is a pretty good compromise. Lasers are after all good against Aerospace so they would be your primary weapons for an Air-Defense vessel while Ballistics would be your go to for Anti-Surface warfare. Missile and Torpedoes remain a swiss army knife.
Proposed (Anti-)Submarine Warfare Rules
Explosions do 2x damage underwater which helps to offset the heavier potential armor that Submarines can mount due to their heavier structure while still making them vulnerable. It also makes torpedoes a serious threat to any other warship.
When on the surface a submarine is treated as a surface ship for detection and LOS purposes.
Underwater Depths - These are treated just like Altitudes although are significantly smaller ranges (because water is heavy), regular submarine combat vehicles cannot go beneath Depth 5 while Battlesea Capital Submarines can reach down to 10. They must however be no greater than Depth 2 in order to launch underwater missile strikes or receive surface communications.
Underwater Sensor and Communications rules - At Depth 1 (Periscope Depth) Submarines have half LOS for both Visual and RADAR detection above the water but can be visually or RADAR spotted at a similar half range. Beneath Depth 1 they only have SONAR and comms with the surface but cannot be detected except via SONAR and MagScan. Beneath Depth 5 they lose comms with the surface for however long they remain submerged.
SONAR like other Double Blind Sensors have a short, medium, long range bracket which differs based on the vehicle type. Subs have 16, 32, 48 MS Range while Surface Ships have 12, 24, 36 MS Range.
Anti-Submarine/Submarine Gear
Dipping SONAR - 8 tons, A VTOL or Airship can hover above the water and can use SONAR sensor rules with a radius of 3 MS to detect underwater vessels or hazards.
Magnetic Anomaly Detector - 8 tons, A superior version of the Magscan. An Aircraft moving at Cruise or less can use MagScan rules to detect the presence of underwater vessels beneath its flightpath (and adjacent lines) but not well enough for a target track.
SONAR Remote Buoy Launcher - 4 tons, 8 shots, Any aircraft can dispense SONAR buoys which provide a R1 detection zone for underwater vessels or hazards. These drift based on air and sea movement.
Depth Charge - 1 bomb slot, treat as a dive bomb, ADCs detonate at a certain depth chosen upon launch. Each deals 10 standard damage.
Hedgehog Depth Charge Discharger (OS) - 10 tons, Any vessel or aircraft mounting a Hedgehog can saturate a map sheet (at a particular depth) with explosives. Treated as a regular Depth Charge attack but rolls on a 10 Cluster roll. Range 2 MS
Capital SONAR Decoy - 10 tons, Apply a +1 penalty to hit to the Torpedo for each released in a Mapsheet.
Seabolt Torpedoes - Thunderbolt Missiles in Torpedo form (just like LRT and SRT launcher types).
Sharkfin Light Torpedoes - Arrow IV Torpedoes, MS Range 4, Same Warhead types (including Davy Crockett-M) twice as much damage because they explode underwater.
Anti-Missile Defense
Same as Space rule with the following additions.
Anti-Missile Systems only fire once per turn.
Arrow IV systems can launch their standard array of missiles including Air-Defense Arrows which can intercept incoming missiles of all types.
Artillery Guns also have their full array of ordnance including Flak for firing against Cruise Missiles (just like any airbreathing fighter).
Doing 10 Standard Damage adds +1 to hit for any incoming Large (Cruise, Sub-Cap, or Cap) missile regardless of when that damage occurs (during transit or in terminal phase).
Alternate Ammo Types
Thunderbolt RAM (Rolling Air Frame) - The Thunderbolt missile is a very large and heavy standard missile which made it ideal for upgrading with better targeting systems compared to the smaller long range or extended long range missiles. These RAM Interceptors use Air-Defense Arrow target modifiers but deal their standard damage like any other weapon.
"Kingfisher" ASROC (Anti-Submarine Rocket) - An alternate warhead type for Cruise Missiles "Kingfisher" ASROCs resolve those attacks as the inverse of an underwater launched Surface to Surface weapon (with a +3 to hit and 1 round 'terminal plunge' delay). Submarines not at Depth 1 cannot detect or engage "Kingfisher" ASROCs unless they have a friendly spotter and are otherwise in a position to do so. Target Depth needs to be decided at launch and cannot be greater than 5 with the commiserate range penalty (+2 MS per Depth). A Kingfisher will engage the first target it encounters within its target hex.
Mollusk Heavy Torpedoes
Similar to Cruise Missiles Heavy Torpedoes move at a Max Speed of 3 with half the range of their airbreathing counterpart in MS. These are treated as combat submersible robots (aggressive) as opposed to drones like their airbreathing counterparts and travel at Depth 1. Unaffected by Capital ECM bonus to defense. Can be targeted by standard weapons, submersibles, depth charges, and even your own Heavy torpedoes just like missile intercepts. Like the Airbreathing Cruise Missiles an Alamo (CM/50-70) or Santa Ana (90-110) Nuclear Warhead can be fitted instead of a conventional warhead with another half reduction in range (but not speed). Base to hit 5
Cuttlefish CM/50 | Nautilus CM/70 | Octopus CM/90 | Giant Squid CM/110
