To expand upon the above, there is an extract from the
GURPS Prime Directive 4th Edition rulebook which discusses how
warp speed in the Star Fleet Universe works.
In the "modern" (
GURPS Prime Directive's Tech Level 12) era, a
Constitution-class heavy cruiser can fight at Warp 3.14 (Speed 31 in
Star Fleet Battles terms); can "cruise" at Warp 7 (which counts as six hexes' worth of "operational movement" on the
hex map used in the strategic-level game
Federation and Empire); and has a "dash" speed of Warp 9.25 (which in
F&E is treated as "strategic movement", and which must make use of "strategic movement nodes", such as bases).
These speeds are adjusted depending on which technology era one is looking at. For example, the
Republic-class early heavy cruiser, the forerunner of the
Constitution-class (and a Tech Level 11 starship in
GPD4e terms), could go no faster than
SFB Speed 25 tactically, had a "cruising" speed of Warp 6, and had no "dash warp" capability. On the other hand, the
Vincennes-class advanced cruiser, a first-generation X-ship (at
GPD4e Tech Level 13), is no faster than the
Constitution-class tactically (but is far more capable of fighting at speeds close to that limit), yet had more powerful engines that can "cruise" at Warp 7.25 and "dash" at Warp 9.5.
As noted in the prior post, ships are forced to slow to tactical warp speeds if approaching (or being approached by) an opponent within weapons range. In
FC, this range is reduced relative to
SFB, where long-range direct-fire weapons such as phaser-4s can oblige a ship to slow at a more significant distance from, say, an enemy base (or a pursuing Juggernaut).
Also, most civilian transports have less powerful engines than naval (or police) ships; a raiding vessel (from an enemy empire, an Orion Pirate, or suchlike) has an easier time of forcing an engagement against a civilian convoy, while a "sheepdog" frigate or police cutter is obliged to defend its charges.
And in addition, not every empire uses the same concepts of operational and strategic warp. Perhaps the most prominent example of this is with the Andromedan Invaders: their ships are somewhat slower than "modern" Alpha Octant warships in operational terms (though exactly how much slower may not be clarified until
F&E Andromedan War is eventually published), yet their unique Rapid Transit Network allows them to move at blistering strategic speeds of Warp 15 between satellite bases, while their Intergalactic Trunk Line seemingly enables even faster speeds for ships deploying to an Andromedan Desecrator starbase from the M31 galaxy.
However, the means by which the RTN was possible also led to their eventual downfall. The only Andromedan ships capable of traversing the RTN are those equipped with displacement devices. However, a side-effect of DisDev operations is that no more than two Andromedan ships can use their DisDevs in the same tactical engagement (though an Andro base on the scene with its positional stabilizers active can use its DisDevs over and above that limit).
Once the Galactic Survey Cruiser
NCC-1802 USS Darwin uncovered the truth about how the Rapid Transit Network operated, the Alpha Octant empires were able to hunt down and destroy the satellite bases (and other, larger RTN nodes) used to facilitate Andromedan strategic operations - and the DisDev limit meant that even if the Andros chose to stay and fight over a given base, they could not amass the combat power in one place needed to hold out against a determined Galactic task force.
Although, this only worked because the Alpha Octant empires still had enough resources left to mount such offensives. One wonders what kind of dark future might have entailed had the
Darwin somehow vanished prior to passing on this key information in a timely manner...