Okay I'm working on my STLPunk setting and I've gotten to the space combat. The general feel of the space combat is a mixture of Star Wars and Bab5. I don't have those Honorverse huge accelerations and long range fights but they are more mobile then Star Wars. Fighters are not the point in this setting but they are still there. There is some capitol scale vessels in they are much less common as they are just starting up.

There are no energy weapons. It is just missiles and coilguns for the most part. There are also no sheilds. I want the setting to have a somewhat low tech feel to it. Some gravity control is available and is the only major tech advance but they are just beginning to really understand it. They have ContraGrav, ArtGrav, Inertial Compensators, and Inertial Displacement Drives (allows them to go between 200 to 400 kps while on). Sheilds that are on the outside of a ship haven't be invented yet but they can create one inside of engines to keep them from blowing up.

Ships are not pretty. They look like the Suloco or an EA Destroyer without the rotating sections.

I visualize capitol ships circling each other at a fair distance (a few kilometers at closest) if they can. They can be caught closer if surprised. It is basically like our own navy doesn't like getting close to other vessels or a coastline. I've got mostly fighters and small corvettes being the ships that fight close. They have stealth capabilities to make it hard to target them (not cloaking devices, just ECM).

Most ship to ship combat occurs at Medium Range (<100km). You have enough information to accurately target your weapons and for your interceptors to work for you but not too much lead time for your enemy to react.
There is a passive and an active sensor lock for weapons. The passive lock will make it harder for the weapon to hit but it will make it harder to counter. The active lock is easier to lock with but also easier to counter. Torpedoes always use passive sensors for targeting because they have infomorphs on board for target analysis. Missiles normally use passive and active sensors. Passive sensors can be fooled by Electronic Deception (ED) systems. Active Sensors can be fooled by ECM.

Ship locks on with a missle. This is an active sensor action. Then they fire.

1) Defender tries to decieve the missile with ED and ECM. The pilot must make a moderate skill test (depending on the range? and maneuverability of the missile) in order to provide the EW Tac Officer the chance to do this. If it is farther out then they can make the test without the pilot's test yet.
If the defender's test fails then the missile keeps it's lock. If they succeed then that missile has lost target.
There is also the possibility of a generalized ECM and ED making it harder to target them in the first place so the initial fire control roll would be low. This should be based on the rating and not on a specific roll from tactical.

2) Defender tries to intercept the missile. This occurs at short range (<2km). The Defender must hold the ship somewhat steady to use interceptors. Basically as long as they have some space they can use the interceptors without trying to dodge. Then they will only have to dodge what gets through.
A good tactical officer can manually control the interceptors and coordinate actions with the pilot so that they can use interceptors and dodge at the same time. This only works well for small numbers of missiles. They can also use the ECM in zones to trick their incoming fire along interceptor zones. A very good tac officer can redirect a missile along a shallow tangent into another target.

3) Defender dodges if it is still there.

Basically this means that all weapons engagements are defined as to how many "steps" are available. This means how many of these actions can be taken. A 2 step defense would force you to choose either to use your interceptors OR dodge because dodging with throw off your interceptors. They will probably shoot wild. A 1 step defense means that ECM and ED have no ability to confuse the weapon's locks. There is not enough space for it to work.
Chases often are maneuvering fights between vessels trying to either open to 3 step or drop to 1 step. This is the basis of chase combat.

I was thinking that the normal way of defining ranges for weapons wouldn't make as much sense. There is no reason for the accuracy to drop for a projectile though the distance would make targeting more difficult. I was thinking about something more based on the step system and basing it on the acceleration rate of the weapon.

Basically a slower weapon at a certain range would give them more defense steps.

Something like this:

Point Blank - 1 step
Short - 2 step
Medium - 3 step

Then I could have the ships acceleration rates change which chart was being used. If the attacker and defender where in a chase with equal accelerations then only the weapons accel counts. If they are charging each other then they add all of them together. Etc.

On the other hand I'm afraid that this detail level will end up causing too many headaches.

Any thoughts?