[gurps] Delta-V the key to a pirate universe?

[Onno Meyer]

What about this one?

* FTL is by hyperdrive. Hyperdrive works only far away from planets 
  and suns (to the order of 10 million miles / 0.1 AU). Hyperdrives 
  are fairly precise, very hard to detect, but come with an 
  inconvenient calculation/preparation time. 

* STL uses a range of reaction engines (plus lightsails for exotic 
  jobs). Usually fusion rockets or optimized fusion rockets, since
  water reaction mass is almost free. Fusion rockets are relatively
  easy to detect.

* A typical commercial craft is 33% unloaded ship, 33% reaction mass 
  and 33% cargo. If it goes from low orbit of one world to low orbit 
  of another, travel speed is a quarter of total delta-V, about 16
  km/s. That means each STL trip means a week or so of coasting. 

* Pirates are up to 60% reaction mass, three times the delta-V, and
  they go to the trouble to refuel in the outer system before a 
  hunt. 

The pirates lurk just outside the FTL exclusion bubble, with a 
constantly updated 'hyperdrive solution' to jump out. They wait 
until an inbound freighter has burned the third quarter of its 
delta-V reserve before they try an intercept. 

The freighter might detect the pirate and call for help, or there 
are patrols out there, but the numbers game makes it likely that 
the pirate can intercept the freighter before a warship can get 
the pirate. Dumping cargo is an option, but then the pirate can
try to salvage the abandoned stuff (possibly even legally, since
it did nothing more illegal than speeding). 

If all works out well, the pirate will intercept the freighter 
perhaps a day into the FTL bubble. If demands to surrender are 
accepted, the pirates board and either steal the most valuable
cargo, or take hostages, or dump most/all cargo, transfer fuel
and steal the ship. If the pirate is forced to shoot, it might
be able to salvage some cargo afterwards. 

Every now and then, a pirate hunter is in position to do to the 
pirate what the pirate did to the freighter. The pirate is a 
harder target than a freighter, with more delta-V to spend, but
the warship is a better hunter, too, possibly with AM drives or 
the like, and real military sensors and weapons. So a warship in 
position to do something will definitely spoil the attack, and 
it might get the pirate.