[DangerousThing]

Originally Posted by Anaraxes

The same is true of the standard Traveller jump drive. You have to defend in depth six parsecs deep since the enemy fleet might appear anywhere. In fact, jump drive makes border defense harder, since there's no way (that I remember) to detect or intercept a ship in jumpspace. The warp drive ship might be, depending on how that's defined. (Star Trek warp drive, yes; Larry Niven hyperdrive, no.)

I use rules which make it difficult to jump into empty space. A gravity well is a lot easier to aim for. Trying to aim for an empty hex is a -6 modifier, and doubles the uncertainty time for a jump. Since militaries like to use formations, this makes it more difficult to keep a fleet together. Therefore, only the critical systems are strongly defended. Also, I only have drives up to J4 in use.

GURPS Traveller: Interstellar Wars uses something similar.

I also use jumpflash, which is em radiation emitted when a ship enters or exits jump space. Its louder when a ship exits. It is possible to jump such that the majority of this flash shines away from the system you are entering, but this is a -4 to the navigation roll. One can minimize the flash with -3 piloting roll.

The consequences of this is that fleets are loud and tend to move in fairly predictable patterns. If they are moving fast, they need to jump to systems with easy refueling. So, if the defense can protect any major refueling points, they can stop a fleet.