My player's ship has Tempormental Warp Engines. I am looking for a little clarity on how they impact the game. It seems to me after discussing it with my players that the time added or subtracted is based on elapsed space time and not actual warp time. This made for an interesting set of events in my first session.

1st the PC navigator did very poorly on his estimation of how long the trip would take.

2nd the PC navigator did very well on his actual navigation roll, cutting the warp time to 1/4 of actual warp time.

3rd as DM I know that the their Warp Engine has added weeks to their elapsed space time based on my rolls behind the screen.

The book indicates that 1 day of warp travel in good conditions should be aproximately 12 days or elapsed space time. Given the nature of the Warp aroun the Maw and the battlefield I figure that ratio needs to be increased. But for now I'll use 12.

Based on my decision that the Journey from Port Wander to the Battlefields was a 10 day warp passage. My players were in the Warp for 2.5 days. Using the base ratio that is 30 days of elapsed space time. I added 21 days for the Warp Engine. Giving me as the DM the knowledge that they have spent 51 days away from Port Wander.

Now from what I can tell they as players have no idea of the amount of time that has elapsed because there is no 'local' time to check in the Battlegrounds, and they likely will not find out the time until they reach Footfall. And they have to use the navigators incorrect estimation for now.

Does that seem to make sense to you more experienced GMs out there?

Similar to the old British method of keeping uniform time across its great empire, I always thought that Astropaths would send out psychic pulses from an Astropath Beacon to signal what the current "real space" time was.

But yes, unless the Navigator does well on his rolls, the GM is supposed to keep the "actual" travel time secret, while the Navigator receives the "best guess" time to convey to the rest of the crew.

They would be ignorant of actual time elapsed, however with an astropath it would be easy to find out.

Also purely in the realm of personal choice you might want to lower the real world time to warp time down from 12 to 1 to something like 2 or 3 to 1 as a base. As a story teller doing this has helped me a lot but mileage may vary.

For my purposes I consider the Koronus Passage to be well-charted but prone to storms, for a modifier of -10 I think.

llsoth said:

Not really. The warp screws with time taken on astropath messages just as much as it screws with ship travel. Lexicanum has an article about how the Imperium defines the date, the first digit is a margin of error for the date.

Bilateralrope said:

And even that would only give you the date at the time it was last sent/relayed (maybe- not all messages include a date-stamp). There are occasions in fluff in which a message has taken years (if not decades) to reach it's destination, and even a few where it has arrived before it was sent (one novel has a task force being sent out to investigate what turns out to be their own distress call).

To get the date they either need to get in vox-contact with a location that knows the actual date (or another ship and guesstimate from the discrepancy in both ship's logs), or to go to a known and charted location and take a star fix. That'd allow them to calculate the time elapsed based on stellar motion/drift from previous star charts.

Good glad to know I am doing that time bit right. To me I am viewing the Maw as an area similar to Cape Horn. Passing through it is a right of passage of its own for voidsmen and for good reason. Even though it is an established route, its passage is perilous, but it is the only known way into the Expanse.

While it is clear that ships go missing in the Warp or wind up far from their destination or potentially much earlier or later than they should have. I am a little confused as to how a flotilla or fleet of ships can reliably remain together when travelling through the Warp. Is it assumend that the ship's navigators can follow each other through the warp like a game of follow the leader? Thus ending up at the same place and time, a greater percentage of the time, with only a few ships going missing. Or are fleets forced to limit themselves to the little point to point jumps to maintain cohesion? A little clarity on how you guys have handled "fleet jumps" would be helpful. The art/fluff seems to indicate fleets travelling and arriving together, but the rules make it unlikely if each ship has to use the rolls of its own navigator.

I've not had to deal with fleet movements yet, but I did have some thoughts on the matter.

Firstly- Navigators can definitely pick out another ship's warp-wake (although in game-terms, I'd recommend either having somehow putting a psychic tracking beacon on the ship to follow, or use the Tracks In The Stars power), assuming the local warp conditions aren't sufficiently tempestuous to totally disturb/dissipate them. You might even substitute the "Charting a Course" step with manifesting Tracks In The Stars (alternatively, reduce the Difficulty of Passage based upon the success/PR of Tracks In The Stars).
In general, however, I'd use this more for following a ship than travelling with it. That is, for following non-allied ships.

Secondly- When co-ordinating fleet and flotilla transits, there are probably two ways to look at it, both just about justified by the fluff:

• Rendez-vous at: the fleet works out their probable best route to the next destination before hand, but makes transit separately and wait at each waypoint until either everyone arrives or a reasonable time has elapsed. This is relatively slow, but ships do get the best advantages before they enter the Warp: in working out thei best route, either the fleet/flotilla's senior Navigator figures out the jump himself and distributes it to the other ships, or the various Navigators work it out together (obviously, this works best if all the Navigators are from the same House, as they guard their charts jealously). In either case, the entire fleet is working from the same Duration of Passage figures (GM's discretion as to whether to allow assists, or whether any bonuses from any shared Navii Primae [not sure if that's the right pluralisation. Meh, it's High Gothic, it looks about right, so It Is] apply to the entire fleet. I'd recommend allowing one and only one Almanac Astrae Divinitus to apply).
  Used explicitly in A. Hoare's Rogue Star and Star of Damocles . Implicit in other sources, including the BfG BBB.
• Formation transit: the fluff does actually allow non-Navigators to see out into the warp, and indeed for Auspices to work. It can be sanity-blasting and the visible range sucks, but it's do-able. A fleet making an Empyrean passage in close formation (including entering the Warp as close to simultaneously as possible) should be able to stay within visual range of one another. As long as they keep formation on the ship with the best Navigator, they should be able to arrive pretty much anywhere at pretty much the same time. The downside of this method is it requires incredible finesse at the helm, and an unexpected warp-squall, or simply bad luck with the currents and tides can easily leave ships out of contact.
  Rules-wise, I'd call for some pretty stringent Pilot checks to get into sufficiently close formation before entering the immaterium, and then skip Steering the Vessel for all but the lead ship in the formation. All other ships get to make some rather nerve-wracking Pilot tests, and quite possibly (or even probably) Insanity and/or Corruption tests for the Helmsmen (including any PC who chooses to lend his stats to the task of steering).
  Ships that get lost separated may find themselves off course, or some other dire circumstance.
  Not used explicitly anywhere in 40k fluff to my knowledge, but rather clearly implicit in D. Abnett's Eisenhorn series, as well as Sabbat Martyr , and in S. Mitchell's Death or Glory . The capacity for non-navigators and auspex to work and see other ships while in Warp attested to in G. Rennie's Execution Hour , D. Abnett's First and Only , I. Watson's Inquisition War and B. J. Bayley's Eye of Terror , and quite possibly other locations.