Greetings,

I'm not sure if this is a rules question or a lore question, so I dropped it in the main forum. Essentially I'm designing an encounter for an Only War game I will be running very soon--it's an Only War game where Act 2 morphs into Only War characters suddenly finding themselves in a DH game--and I had a question about boarding actions while two ships are in warp.

I have every core book at this point, and have only scanned RT. In addition mastery of Warhammer Lore extends to 15 years of unused knowledge about the fantasy setting, not 40k. Given this, I was able to find one comment page 185 of the RT core book stating boarding ships in warp is sometimes worth it, but no hard and fast rules.

So, either in mechanics or just in what you think would happen, what does boarding a derelict ship in warp look like? Do the boarding shuttles have Gellar fields? Or can a ship with Gellar fields extend them around a ship without them? Mainly I'm curious if the troops/personnel in the boarding shuttles are open to warp intrusion and if the same is true once the boarding party actually makes it onto the ship.

I'm also assuming visual navigation is impossible (and on board windows are always blacked out for warp travel) since navigators are the only ones who can "gaze" on the warp without having their minds destroyed. And finally, if this is the case, how do shuttles make it to the ship at all? Do regular "sensors" work in the warp so that instrument flying is possible?"

Thanks.

I am far from an expert, but I'd assume normal sensors work fine (with perhaps some anomalies) once the Navigator has located the ship you intend to board. The reason sensors don't work in the Warp normally is that there is nothing for them to sense - the roiling chaos that is the Warp has next to no physical objects in it, and the chaos itself doesn't (typically) show up to any kind of mundane sensor. Sure, it could manifest things that do show up, and confuse the sensors, but I'd assume another ship from the real world that simply got trapped in the Warp should still show up on them, too.

I can't imagine the Geller Field reaching far beyond the ship it's on, though, unless you have some kind of xenos artefact projecting your defense. Maybe you could get close enough to transfer to the other ship's Geller Field without being exposed to the raw Warp if that ship's field is still functioning… and face it, if it isn't, the ship would likely have been torn to component motes and scattered into nothingness by now if it weren't.

And yeah, don't look out upon the Warp with your eyes, obviously. Sensors only. If there's a small space between the Geller Fields, a few demons materializing or a few shuttles lost (or both) is probably the best way to handle it… if the PC party is going to the other ship, maybe they (and perhaps one other shuttle) are the only ones to make it. If they're the only ones going to start with… no clue what to tell you.

Actually any vessel with a Gellar field generator can adjust it to cover other nearby vessels. The generator creates a field that is a lot bigger than the ship - it doesn't hug the hull of the vessel but instead creates an ellipsoid of 'real space' around the vessel to allow it to exist inside the laws of physics. The warp drive then propels said ellipsoid through the warp.

To board another vessel in the warp you would need to succeed on some tricky piloting manouvers to come alongside the other vessel, some complex tech-use tests to adjust the gellar field to cover both ships. Then once the other vessel has been enveloped you can either physically dock with it using umbilicals and boarding clamps if your vessel has them (GM fiat at this point) or you could teleport over or most dangerous of all use shuttles, boarding torpedos or drop-pod bays.

Once aboard the other ship the primary goal will be to get the plasma reactors online and once the ship has power to enable its own gellar field so that your vessel need not extend its own field. Then you pretty much piggy-back off your own vessel and navigate (albeit slowly) out of the warp. Et voila, you have salvaged a vessel from the warp.

Of course this is the simplified version that presumes the vessel isn't infested with crazed or mutated remnants of its crew or dameons or even chaos space marines. Combat should pretty much be a given whilst on board the vessel, and pulling it out of the warp should not be the end of your callenge - the vessel will need thoroughly cleansing, re-consecrating and an explorator crew go over it with a fine toothed comb to learn all they can about it.

Shuttles don't come equipped with Geller Fields, no. In theory, the largest of shuttles (I'm thinking stuff like the Halo Barge and bigger) could have the space to be fitted with one, but that would massively cut down on their maximum payload capacity, be very expensive, and there's no guarantee they have sufficient power to run it and their other systems. So, basically, yeah, your best bet is to come close enough to either merge Geller Fields with your target, or extend your own around them before launching your boarding craft.
This means launching from mere tens or (at most) hundreds of kilometers away, as opposed to up to 50,000km away. Your shuttles are essentially going to be in range of any hostile point defence immediately from launch (and that's one of the most vulnerable points of their flight)

Now, everything already said on that subject holds true, but it assumes a target ship that is either co-operating or disabled, which wouldn't be that hard (or at least be a routine if hazardous task) in real space (it's basically first stage in docking maneuvers). In the Warp, however, there are all kinds of unforeseen turbulence, currents and perturbations that could make the task trickier.
If the target ship is not disabled/co-operating, and is actively trying to maneuver away, it becomes a test and display of your helmsman's finesse and skill, as he's now got to try and maintain a close formation on an unpredictably maneuvering and evading target at the sort of distance where you could almost hit the other ship by throwing a rock out the airlock.

I'd be less sanguine about trusting your auspex in the Warp. Yes, it does work, for a given value of "work", but the thing to remember about the Warp is it's not just a lack of reality (and full of daemons and similar), it's a roiling tempest of energies and irrealities, might-have-beens and never-were. Even when it's calm and clear out, the most you can really see before your auspex returns decohere into a morass of interference and impossible false positives is what would be considered practically knife-fighting range for ships (again, down to hundreds of kilometers- at most 1 or 2 VU (ie 20,000km)). But in terms of sensor returns you can trust with absolute certainty- your auspex range is limited to whatever is within your Geller Field.

For that matter, just finding the other ship is a damned impressive feat of Navigation. Following it, yes, that's doable (it is, after all what Tracks In The Stars was designed for), but actually finding and engaging it? Nowhere near as easy. In fact, I can only think of 3 occasions in fluff of engagements that happened in the Warp itself, as opposed to tracking someone and ambushing them in realspace. Of those, one was a pre-arranged rendezvous (which is impressive enough*); one was a cunning trap, wherein an ork ship held its position(!), probably for weeks, on the warp tides just out from the probable translation point an incoming Imperial convoy was going to use**; and one was an extended chase through both Warp and real space***. All of those are real bravura displays of voidsmanship.
That's not to say it couldn't happen, but it's hardly an every day occurrence.

*It's also the only occasion I know of with successful boarding and EVA in the Warp. In this case, the target was not merely co-operating, it had a far larger active Geller Field. And had both daemonic and probably eldar help keeping station.

** Unfortunately, it wasn't a trap any particular ship and crew could pull off more than once, as said ship was full of Weirdboyz (psykers), who worked together to create a nasty flare/shockwave to force the convoy back into real space early. That had the nasty side effect of attracting the attention of every daemon and warp creature for quite some "distance". They ate it.

*** The pursuing vessel in this case was the chaos ship Contagion . I think using daemons to find ships in the warp is probably cheating, considering, but it's still impressive. Admittedly, not quite as impressive as what Contagion 's intended prey (HDMS Lord Solar Macharius ) did to win: dropped the power to the Geller Field all the way to 40% to lure Contagion in to closer than point-blank range, before powering up and coming about to hit Contagion with a ridiculously close-range torpedo salvo.