Update: There is now a wiki entry for jumpdrives, which supercedes this.
Maybe there are the jumpspace equivalent of Hadley cells circulating above and below the map plane, and converging in (and through) each gate/correspondence zone. If you want to go the opposite direction, you have to "rise" or "sink" in the plane, to catch the current going the right direction. The current is strongest in the exact line(s) between the two gates, but if you want to sneak or avoid pirates or whatever, you follow a little (or a lot, if you have enough sail to still get to your destination in time) out of line.
And maybe you have to have enough sail (J2+) to get around the pull of the gate if you want to keep going... though this means a J1 ship could sail through an empty hex... unless it's an unformed correspondence zone that would wreck a ship. (And maybe an extremely skilled pilot can pull it off with an underpowered ship.)
And maybe this is why a jump can't just be initiated from a planet? You have to have enough escape velocity (perpendicular to the jump plane/system ecliptic) to get away from the gate in jumpspace? Or it's the correspondence pull of a planet that actually drops you out, I guess, though that changes the "it's the jump charge decaying that drops you out" which, to be honest, I'm starting to think I'll get away from.
Hmm.
Trade winds
Update: There is now a wiki entry for jumpdrives, which supercedes this.
If jumpspace has currents, and starships basically sail them, then that can affect the time it takes to get from one system to another, possibly on a "seasonal" basis. There's a lot of ways to set this up.
Maybe there's a lot of different currents, that only slowly shift, meaning starcharts are a map of the multiple known paths between systems. You're not likely to encounter a ship going the opposite direction (and in fact if ships passively "sail" it's basically impossible to go against the wind unless there's some mechanism that acts like a sailing ship's keel to let you tack)..
Maybe, since this is already a more or less artificial construction, there are specific "chutes" of current and you have to be in the singular (albeit large) right one to get to the system you want to go to, and you're becalmed if you get out of it (though there's enough eddying currents around it to work your way back in - or you can shape your jump fields to actively "swim" but that's very energy-demanding).
Having to have currents might fix my issue of "if ships can stay indefinitely in jumpspace, there are no uncrossable rifts. Maybe the rifts are areas where there is no current (or maybe even no jumpspace medium to push against).
Hmm.
Launching boats
Update: There is now a wiki entry for jumpdrives, which supercedes this.
If temporarily leaving the jump bubble is possible, then it's probably possible to launch small craft from a starship in jumpspace, so long as they make it back inside a field before their grace period ends.
This brings back the possibility of fighter-carrying tenders, and whaleboats, and whatever.
This also makes for an interesting possibility: what if you chuck a shuttle out as you're passing through a system? It can drop out insystem without you having to stop. Same for cans!
Jumpspace life
Update: There is now a wiki entry for voidlife, which supercedes this.
All life in jumpspace has a field membrane, essentially the same field that sustains a jump bubble. The interior is not connected to the same realspace: a creature whose field membrane collapses will eventually drop out of jumpspace but not appear in realspace even within a correspondence zone.
The membrane does not seem to require much if any energy to sustain, unlike a jump field, and some lifeforms draw down into a "cyst" to drift between systems. Some lifeforms never change the shape of their membranes, drifting on currents, others shape their field membrane to catch currents like a jump ship, or to actively swim/fly through the jumpspace medium. Some have permanent structures to do this, while others have amorphous fields they shape as needed.
Some lifeforms in correspondence zones, evidently drawing power from the gate. These are usually, but not always, passive drifters, and are usually referred to as "plants" or "algae," though the parallels don't strictly hold up.
Life in jumpspace tends to follow a rough form. Inside the membrane is a layer of exoplasm: a clear layer with a texture ranging from gelatinous to rubbery. It is almost undetectable in the tiniest lifeforms, up to a significant percentage of volume in larger deep-space. It stores gate energy in a field matrix, and is the source of the energy that allows starships to enter jumpspace.
Most have a "skeleton" in the form of a web of filaments. It may be rigidly structural, or may stretch and flex, though in the latter case it doesn't seem to be responsible for the motion.
The largest organ is usually the "core," a large roughly-spherical object surrounded by a labyrinthine array of concentric, spaced layers. Some have paired cores, and others have a distributed system of dozens. It is generally considered to be the brain, but in any event is vital.
Predatory creatures will ingest prey either through a fixed opening in the membrane or by creating a temporary pocket to engulf them; the digestive organ(s) will usually travel to the site in that case, though some seem to produce them ad hoc.
Reversing course
Update: There is now a wiki entry for voidlife, which supercedes this.
What if voidwhales aren't sentient at all, and it's only the parallels to Earth (etc.) cetaceans that convinces some people they are?
I thought of this yesterday and then took it even further: what if they're dumb as rocks? What if voidspace is more like a microscopic world, full of the equivalent of single-celled organisms?
Whaling ships
Update: There is now a wiki entry for voidlife, which supercedes this.
The Pequod had a crew of about thirty, which is substantially more than a PC group... so if that's standard for my universe, whaling starships have to be considerably larger than typical tramp freighters. Which is probably fair, if they're on long-range trips. The Pequod expected to be on a three-year trip, around the globe, not just hunting a whale and bringing it home. It's an interesting indicator of just how valuable whale oil was, that a single ship-ful could justify a trip of that length.
I'm starting to rethink the idea that the whales are only energy creatures. I start to think: what if sharks and lesser fish are energy-only, and the difference in the whales is that they have at least some physical body that can be brought back to realspace and that has some practical use(s), a la whalebone/baleen. Some whales are hunted just for that, and it's something that gives Terran ships an edge.
One possibility I've thought about to work around the voidwhales being the only source of the energy that gets you to voidspace: maybe Terrans and Gvazda kill whales while Inukari and Zhdez just catch-and-release?
Empathy
At risk of bringing Current Events into my imaginary world: rightwingers on the various extremist microblogging sites have fixated on the "PROFESSIONAL-grade logistics" as an indicator that the Minnesota observers are secretly funded by Soros or whoever. And Romancelandia on Bluesky has realized: these are cis men who do not understand how (mostly) women in kids' sports and offices and churches and basically every kind of social construct work. This is just a thing we do!
I guess I've been subconsciously processing this because I've been building the Zhdez as "what if this wasn't a gendered thing, and instead everyone in the society felt this way?" The Terrans dismiss it either as "you're all effeminate" or "it's because you're all telepathically coerced into... being nice to each other."
