Jumping, Jump Masking, and Jump Shadowing

So, as I delve into ProtoTraveller I am confronted by the issue of Jumping – and will ignore (for the moment) Mongoose Traveller’s introduction of Warp Travel and Hyperspace.

Jumping is the Traveller term for Interstellar travel. Ships use Jumpspace to travel faster-than-light, with certain strictures.

  1. All Jumps last roughly one week in length (with variance measured in hours, rather than days). Anything else is a sign of a Misjump.
    • Okay, one quick diversion to Warp Travel and Hyperdrive from Mongoose Traveller. These both, as per the MgT RAW, speed up travel to be measured in days rather than weeks.
  2. Jumps are limited in distance, with the distance being determined by the tech level of the ship.
    • The original game and all editions up to T5 limited travel to Jump-6, this meant that in one week, the ship will travel six parsecs. Jump-1, the ships travels one parsec in one week. This was probably ignored in house rules as much as it was rigorously enforced – gamers being gamers.
    • In T5 (the much maligned Traveller 5th Edition, though not nearly as maligned as Traveller: The New Era) Jump goes up to 9, and Hop and Skip are introduced which scale up by factors of 10x and 100x respectively. These both, as well as the post-6 Jump numbers, occur only at much higher technological levels.
    • Misjumps can be up to Jump-36 in distance (or even longer with Referee fiat), rolled 1d6x1d6 when it is determined that a Misjump has occurred.
    • This suggested different levels or dimensions of Jumpspace, mostly by making sense of the Small Ship Universe ship construction system as compared to the Big Ship Universe.
  3. Entering or leaving Jumpspace is impacted by gravity wells -often causing Misjumps or a violent exit from Jumpspace.
    • In the game this meant that you had to travel “100 Diameters” from a planets surface before you could safely Jump. Technically you could Jump 10 Diameters out from the surface, but it was more difficult and dangerous.
    • Technically speaking, as people have extrapolated across the years (and editions) this also means that gravity wells of ships and stars. For ships, the distances are generally too miniscule to worry about (but the question is inevitably raised when someone wants to Jump a ship that is in larger ship’s hold, usually because they are captured by pirates). While stars… well that just tends to get ignored – unless you (like me) tend towards the OCD.
      • A professor of mine in grad school said that in order to be successful in grad school you had to at least a touch OCD. The key, as he put it, was to keep in on the Obsessive side instead of the Compulsive.
    • Some argument has existed as to if Jumps needed to start and end in a star system (essentially that ships used the gravity well of a system to “catch themselves” out of Jumpspace). This came from the old Imperium boardgame where this was the case, and is evidently a canon bit of history. But technology evidently allows this to change – with scattered references to deep space refueling stations or other forms of calibration points.
  4. Starships must be at least 100 dtons in size.
    • An issue raised by the now utterly non-canon, but once (and still) questionable existence of “Jump Torps” – something that I love, but that seriously conflict with the canon OTU despite being listed in the old (and much loved) Adventure 4: Leviathan.
    • As an additional note, in standard Traveller Jump Fuel requires 10% of the ships volume per Jump Number – as a one-time expenditure. So Jump-6, that’s 60% of the ship allocated to a one-way trip.

That gets us to Jump Shadowing and Jump Masking, which were only explicitly described in Traveller: The New Era (in their search for gritty realism). Later, in the GURPS: Traveller Far Trader supplement is the first (and only to my recollection) rules for actually incorporating them into play.

Jump Masking is when significant interstellar body intersects the path of a ship in Jumpspace. Jump Shadowing is when the destination point of a Jump-travelling ship lies within a gravity well of an interstellar body.

It doesn’t seem to me to be that hard to do an idiot simple tweak to the Jump rules to handle both Jump Masking and Jump Shadowing – as well as incorporate a old idea into what also feels like a very ProtoTraveller setting.

In Mongoose Traveller, using the Astrogation skill to plot a Jump is normally an Easy (+4) Education check, modified by the Jump distance (so, -1 to -6). It effect this means that unless the attempt is rushed along it is probably always going to succeed. In ProtoTraveller the idea is that travel is somewhat dangerous. Think more like world travel before the advent of flight – maybe not as dangerous as the Middle Ages, but more in the nature of the 18th or 19th century.

So, let’s say that those rules (mostly) apply to well-mapped trade routes (we’ll get to that in a moment). It still doesn’t cover Masking and Shadowing – and here is the simple fix. For Jump Shadowing add a -1 Modifier for every star in the system while for Jump Masking, when plotting the Jump simply add a -1 modifier for every system that the route intersects.

Normally, Jump takes 148+6d6 hours. In the event of Jump Shadowing, if the navigator doesn’t wish to take the Difficulty penalty then instead add +6d6 hours of travel for every modifier for the Jump Shadowing that they wish to avoid. This represents them targeting a point further and further out to avoid the Jump Shadow – though at the expense of longer and longer in-system transit time.

Now we can also say that plotting a Jump to a Backwater system (off the Trade Routes)in the Core Worlds is a Routine Education check the same as Frontier systems on Trade Routes. Backwater systems in the Frontier are a Difficult Education check while truly unknown systems are Very Difficult Education checks to plot a course to.

This also has the effect of channeling travel around “dangerous systems” and towards “safer systems” – essentially “rocks, shoals, and reefs” for the Traveller system. That’s before we add in other potential effects for nebula, black holes, etc. It also means that you can really create “hidden bases” or “protected systems” because certain systems are just a huge pain in the ass to get to.

Now, in the “real world” navigators had “rutters” which were their private (and secret) notes and charts for navigational hazards. Anyone who has read or watched Shogun should be able to recall the discussion around the existence and the secrecy of these things. When we add in these sort of navigational hazards and complications the use and desirability of a “jump rutter” become apparent.

So, we could simply suggest that ship navigators keep and maintain “jump rutters” which they create (and pass on to apprentices, or family members in the case of Free Traders). Through experience in Jumping to various systems navigators can essentially create their Trade Routes, even their own “Core Worlds” with enough time and enough Jumps.

This also explains why (or how) the small Free Traders and Tramp Freighters maintain a viable economic presence. They are the only ones that know the safe routes to the Backwater and Frontier worlds. Similarly, it also explains how pirates manage to exist and remain viable – they haunt the long spaces where ships avoiding Jump Shadow travel, and have found “secret asteroid or nebula bases” where they can hide in safety.

TTFN!

D.

 

 

 

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Categories: Campaign Development, Game Design, House Rules | Tags: , , , , , , , , | 2 Comments

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2 thoughts on “Jumping, Jump Masking, and Jump Shadowing

  1. Matt s

    See, what bugs me is that “100 diameters” business. If gravity is the problem, it should be proportional to mass, which is proportional to the volume, not the linear dimension.

    And it should fall off as the inverse square of distance.

    • ROFL! You’re not the only one, and there reams and reams of tables and formula that allow people to calculate according to tidal forces rather than strictly gravity, as well as by the composition of the planet (which obviously affects mass, which affects gravity), and a variety of things such as that.

      It’s not a horrible method of calculating things – but it *really* falls apart around things like Gas Giants (Jupiter) and the stars themselves where measuring “diameter” starts to fall part quickly.

      D.

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