how about just straight forward vector addition?
you'd have to pick a scale for each hex and assign rates of accelleration and decelleration to the ships.
For range determination, just # of hexes (or squares) X scale = distance to target.
You can use a simple percentage system for weapons "chance to hit".
Say a weapon is 100% accurate at 1 hex and 0% accurate at 10 hexes.
Each hex adds or takes away 10% (in this case).
The hardest part would be creating the stats for each ship.
You have to compare them during your build and make sure they add up right.
So, Ship "A" has greater speed but less manuever. Ship "B" is the opposite.
At the end of the day, all done proper, the game should be decided by tactics of the players.
I've assisted in a number of game designs. It CAN get complicated, but doesn't have to be.