Making "Fleet Jumps" in Traveller...

[Lord Kalvan of Otherwhen]

Perhaps this was more appropriately posted here...

When a fleet or squadron makes a jump from one system to another, do they all arrive at the same time (like in Star Wars), or do they arrive independently, within hours (or even days) of each other? In addition, do they arrive at their destination in close proximity to each other or scattered about the system?

This has major implications regarding ship design, squadron & fleet composition, as well as tactics & strategy.

 

[aramis]

MTJ had, in the official MT Q&A, a ruling that it was harder to do a coordinated jump, (ISTR +1 Diff, which equals a CT DM-4), and all arrive within about an hour of each other, but which hour is the normal 168±10% hours.

 

[Bob Weaver]

Originally posted by Lord Kalvan of Otherwhen:

This has major implications regarding ship design, squadron & fleet composition, as well as tactics & strategy. [/QB]

Kalvan,
I agree that arrival coordination will have an impact on strategy and composition, but how will it affect ship design?
IMTU, I once set up a fleet action in which the defenders knew the attack was coming, and where. So the defense force was able to counter-attack as the 'attacking' units arrived; and were therefore able to defeat a much larger force by taking it out piece by piece. The "attacking" force even made use of the 'coordinated jump' addenda, but the fleet was still spread out over five HG2 turns. Without the coordination, it could have been spread out even more.
If you've got some house rules worked up to cover this sort of thing, I'd like to see them.

Best Regards,

Bob

 

[Border Reiver]

Thought I would copy and paste this here for completeness. Joe Fugate in MTJ 2 with MWM's help.

"When a group of starships know they have to arrive in unison they elect to spend significantly more time at the start computing and sharing jump vector computations. This leads to a much more accurate jump exit at the other end with the error dropping significantly.

The formula in the Starship Operator's Manual for normal jumpspace exit is:

124hrs + (2D x 6 hrs)
yielding a result of 136 - 196 hours (that is 5.7 to 8.2 days)

If double the jump preparation time is spent with all the affected ships in computer linl via tight beam communication, use the following formula instead:

167 hours = (2d x 0.1 hr)
yielding a result of 167.2 - 168.2 hours.

Most ships now arrive within minutes of each other, with the worst spread being up to 60 minutes apart (and this only happens in about 1 out of 20 jumps). Considering the vast distances found in a star system, starships arriving minutes apart would not spoil a surprise arrival.

Constant communication during the jump vector generate (sic) is essential for this to work, and double the normal vector generation time must be observed. But when getting there "on a dime" timewise is essential then this technique is the key. Most civilian vessels don't need this level of schedule precision, so they don't bother."

 

[Greek Letter Moshpit]

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> Well, as I'm a maths graduate (and a GT player), my spin on things is a little more complicated.

The standard jump duration, sans misjump, is 168 hours, +/- 10 percent, or 16.8 hours.


The quote above seems to reinforce my intuition that Jump time is a Gaussian process with 3 sigma limits given,
viz, mean 168 hours, sigma 5.4 hours. ( If you don't like the sigma limits used, change them - I'm not claiming this is holy writ )

I break up that variability into two components: first is the shift of the mean duration for that jump,
and second is the individual ship's actual jump duration derived from the shifted mean.

These two shifts are zero mean processes with identical sigma, namely, for number of ships N and

astrogation margin of success k, 5.4 / sqrt ( 2 * ( N + k ) ). Since standard deviation adds in quadrature, the observed total deviation
then becomes 5.4 / sqrt ( N + k ). Or, in other words, the margin of success increases the effective number of ships jumping.

If you want to allow a margin of failure to still produce a successful jump ( ie, -N < k < 0 ), go for it.

After all that, we can finally get to something usable in a game. ( I'm calling the component deviation D here to save typing ).

1. Mean of jump
Mean jump time = 168 + ( 4d6 - 14 ) * D / 3

2. Individual jump duration
Individual jump time = Mean jump time + ( 4d6 - 14 ) * D / 3

Repeat 2 for as many ships as are jumping.</pre>[/QUOTE]Sorry for the use of the code tags, but I couldn't get it to post otherwise.

 

[Greek Letter Moshpit]

Sorry for borking the formatting. Could a mod please fix it up?

 

[aramis]

GLM: just hit the edit button, and add some returns...

BTW< the edit button looks like pencil and paper.

 

[jawillroy]

GLM, you're making my head 'splodey.

IMTU, it's not generally possible to coordinate jump to such a degree, but since I also stick to book 2 detection ranges, this isn't such a big deal: A single raider, hitting a lightly defended system, will pop in at 100d and get busy. But a full fleet will jump in way out on the rim of a system, set up its fighter screen, wait for the fleet to assemble and then start moving insystem.

I run a small ship LBB2 game, but because of the inability to precisely calculate jump times, carrier-rider tactics are useful: A 4000 ton carrier can jump in and deploy a few 300-ton riders and a couple squadrons of fighters much more quickly than a fleet jumpships of comparable firepower can be counted on to assemble.

 

[The Oz]

Originally posted by Imperium Festerium:
I run a small ship LBB2 game, but because of the inability to precisely calculate jump times, carrier-rider tactics are useful: A 4000 ton carrier can jump in and deploy a few 300-ton riders and a couple squadrons of fighters much more quickly than a fleet jumpships of comparable firepower can be counted on to assemble.

This is a justification for carriers/tenders that I've never heard before, but it does make some sense, if that's how jump works IYTU.

 

[jawillroy]

>This is a justification for carriers/tenders
>that I've never heard before, but it does make
>some sense, if that's how jump works IYTU.

Thanky!

The standard rationale (no jump drive/fuel means bigger power plant/m drive blahblah) also applies here, though less than if I were running a High Guard TU.

 

[Greek Letter Moshpit]

Originally posted by Imperium Festerium:
GLM, you're making my head 'splodey.

Ain't that hard a system to use, since I scavenged the guts of it from GT:FT.

Works for any size of ship (even TNE's jump packets), too.

What exactly was so hard to understand in the post, apart from the formatting?

 

[Valarian]

I agree with Imperium. Coordinate the jump as best as possible to a staging area well outside the 100d limit. Then wait until the majority of the fleet has arrived, before proceeding in-system on maneuver drive.

 

[The Hinterworlds Rambler]

Most large ships have Model 9s or in that area, as well as formidable communication gear. In my game they talk, link up and all program jump together. Mantennace on a proper scale prevents misjumps/coming out early/late. I make the assumption that these machines are a little more sophisticated than a laptop.

 

[jawillroy]

And I make the assumption that plotting a jump is a little more complicated than MapQuesting your way from Brooklyn to Paramus. WhatEver. YMMV.