When in control of a fleet (say 2-3 ships) Is there one navigation test per vessel per jump or could the navigator in one of the ships make a single test and act as a beacon of sorts so the others, perhaps crewed by a less skilled navigator, can follow them without much difficulty? I kind of have the idea of a small raider guiding a crippled/undermanned/navigatorless behemoth through the warp. Are there any rules that directly address this?

As long as both ships have a navigator then i reckon it should not be a problem with the first doing a test and the second "simply" following the first ship (i'd still let the second do a test, but give him a +30 on it, more if it's a bigass ship he's following).

Without a navigator on the second, then i think you'd need to "tow" it through the warp, a job for which you need specialised equipment imo. You need a ship built to be able to handle the strain from towing, you'll need a "line" strong enough to handle the pull, and you'll likely need geller field generators on that line in order for it to remain safe during transit in the warp (otherways i imagine the empyrean might work it's foul tricks and turn the rope into candy or a eel-like daemon or something of the like)

I think that a strict reading of the rules requires a navigator on each vessel, and each vessel makes a separate journey.

That being said, I would probably allow a group of ships to make a singe navigation roll, if the navigators work together to navigate. That may not always be possible if the navigators are not from the same house.

For a tow, I usually make it a skill challenge to get from setting to tow to emergence into the destination system. Mostly using tech use, navigation and piloting to keep everything together. I also require that the two ship at least have a working geller field too.

In a hypothetical hit and run in the warp, or even just transferring between ships via shuttle, is it understood that the shuttle has its own gellar field generator? Fighters too I imagine would need them or else your just chumming the waters.

Vendetta said:

Small craft have no Gellar Fields.

What you've just said could be done in theory if two starships moved close enough that their Gellar Fields overlapped, since despite leaving the ship the small craft will never leave the Gellar Field. If they did leave it- well, just hope you're not on a ship where that happens.

In practice, I very much doubt you'd find anyone remotely familiar with Warp travel willing to try such a thing. It'd be like two ships at sea lowering a boat from one that rows over to the other and gets picked up by it- in the middle of a storm. Yes, in theory you might make it, but in practice the more experienced a sailor is the less willing they'd be to try it.

one of the horus heresy books has a bit where it describes two sisters of silence ships in the warp. The sisters of the second ship calibrate their gellar field to "link" up to the one from the first (without the first ship helping i might add) so that they create a bubble in the warp allowing them to go aboard the first ship.

I make 'em use astropaths. The astropath's power roll gives the following Navigator a boost on his roll to coordinate his ship's re-emergence into real space, something like +10 for a flat success, raised by +10 for each two degrees of success.

I agree with Badlapje and Tantavalist's statements. It's mentioned in several novels and books, that small craft don't have gellar fields and that ships can create a small bubble in the warp (if they are close enough) that connects the two or three together. Although, I'm sure you can implement some house rules stating that both ships need to do an Easy Nav (Warp) test to not jink or jive (if in a calm area) while a craft goes from one ship to another.

Anyhoot, as for the "Traversing the warp with multiple ships" and utilizing the other navigators knowledge and experience to make the trip safer, it could go something like this going off what Badlapje stated. I'm using two ships with two Navigator's, and page 184 RT Core, so bear with me.

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GM Determines Duration of trip (Navigators can roll Nav [Warp] to guess, and once computed combine their results and halve to get a 'guessed' figure)

Navigators make Ordinary Aware test to find Astronomican. Once again compute the results, and they can either be combined and halved, or go off the best once's score. This is due to the fact that if you are looking for say, a ship in the distance of an ocean, the one that noticed the ship can guide the others eyes (senses) to see what he sees or dismiss it as nothing.

Navigators make Ordinary Perception test to discover perils during warp travel. These results can be computed, then combined and halved due to the fact that one person might notice some turbulence in an area, and the other not notice the turbulence but notice an anomaly in a different area.

The best Navigator does a Nav (Warp) to steer his vessel through the warp. The other can follow in his wake with a +30. Of course, if severe storms hit them, than one might lose sight of the other and be left on his own. GM discretion is advised.

The best Navigator makes Hard Perception test to exit warp safely without hitting an anomaly. The other ship can wait for Astropath confirmation of a safe exit, or do a separate check on his own if unwilling/unable to wait. Or, one ship can follow the other ship with using only the first Navigators results.

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And there you have it. An easy to use House Rule format, posted in the Rules Questions section. Everything subject to GM and FFG approval and clarification. GM discretion is advised.