"After a jump, the K-F drive must be recharged, which is a slow and delicate process. The most common way is for the JumpShip to turn its stern towards the sun and deploy its Jump Sail, essentially a huge solar collector resembling a parachute about one kilometer in diameter.
Station keeping thrusters allow the ship to maintain its position at the jump point and counter the downward drift toward the local star induced from the faint solar gravity at the standard (zenith and nadir) jump points which are stationary locations, not stable orbits"
This is the revised description, after somebody ran the numbers.
The old, first edition-type explanation was that the jumpships would turn their stern away from the local star. deploy their jumpsails, and then hang from the sail, nose-down, both recharging the jump drive and being held up by the light-pressure on the sail without having to use any engine thrust.
Nice idea, but someone put the decimal points in the wrong place.
Turns out, just a little calculating with F = m2* a = G * m1 * m2 / r^2, cancelling out the m2's and factoring in the mass of our Sun and the published distance for a jump point, the gravitational acceleration at zenith or nadir is a straight up ~0.1 G.
Light pressure, even adding in solar wind, is many orders of magnitude less than gravitational pull. If they hand-waved some kind of mechanism for the sail to produce 0.1G, they'd be looking at a structure that would weigh more than the rest of the Jumpship and payload combined.
So the new mechanics have the jump sail being essentially a big foldable solar panel that happens to (hand-wave) produce the kind of nice, smooth electrical current the KF drive likes. There's a big hole in the sail at the center to let through the drive plume from the jumpship's station-keeping drive at 0.1G thrust. The thrust and perhaps some light pressure spread out the sail.
Notionally, you don't have to go to the zenith or nadir to jump, just out a few AU, but deploying a sail in the ecliptic is a great way to get holes in the sail from small particles in solar orbit. Not a lot of rocks on solar-polar orbits.
Presumably, one of the things you'd have to do with the Jumpship's station keeping drive is thrust slightly higher than 0.1G so the ship can climb a bit further away from the star. When it is time to dock ships for the jump, you can't do it while the dropships or the jumpship are under thrust, or someone is going to get high energy nuclear rocket exhaust in the face. So, basically, when the KF drive is charged and they're ready to go, the Jumpship and all the Dropships that have been holding station with it cut their drives, start falling, and dock using maneuvering thrusters. No problem, they just have to finish their docking in free-fall before they drop below the minimum distance for jump. Lots of room in space for someone with a little forward planning. Come out the other end, all the Dropships unlatch in free-fall, move away, then the Jumpship swings its nose around, lights up the station-keeping drive, shimmies out the jump-sail and lather, rinse, repeat.
And this means the Jumpship needs fuel, regularly. I wonder what kind of discount you can negotiate for several tons of fuel... or if turning over some fuel is just part of the deal, like bringing a bottle to a party. Maybe there's a surcharge if you don't fork over some fuel, plus a reputation for being the jerk that doesn't contribute to keeping the Jumpship in the sky.
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