Jump Space Duration

[Hal]

I'm probably not the first one to mention this, but if this idea is useful...

When rolling for jump space duration, instead of picking some arbitrary number and rolling an arbitrary number of dice to add to that number to give actual time spent in jump space, why not use the simple formula:

Jump Space duration (normal jumps, not mis-jumps) = 168 hours x (1+((4d6-14)/100)

The average die roll for 2d6 = 7. The average die roll for 4d6 is 14. The range of rolls will be 4 to 24.

Net result of 4d6-14 will give a range of:

04-14 = -10
24-14 = +10

1+(-10/100) = .9
1+(10/100) = 1.1

Thus, a range of time that is equal to +/- 10%

Example:

Roll of a 19 will result in:

1+(19-14)/100) x 168 hrs or 176.4 hrs.

A roll of an 8 results in:

1+((8-14)/100)*168 = 157.92 hrs

 

[SanDragon]

MegaTraveller Imperial Encyclopedia has a D6 roll, 1 = 6 days, 2-5 = 7 days, 6 = 8 days, which I thought was rather bland.

Starship Operater's Manual has 124 hours + 2D x 6 hours. Still not crunchy enough.

I penciled in 124 + 12D hours for civilian operations and, if double the preparation time is taken for a more accurate entry time, 167 + (3D x 0.1 hours) for military operations as they calculate and communicate jump calculations before fleet jumps.

Mmm... crunchy.

 

[rancke]

I use 140+8D hours. IIRC T20 used 147+6D hours. Crunchy enough for me.

One that would get very close to the +/- 10% would be 143½+7D.


Hans

 

[mike wightman]

There has to be a way to use the 1d6 by 1d6 matrix for this...

HG2 has 150 - 175 hours for jump duration., so you are looking for a random number of between 1 and 26 - to which you add 149, hmm - 5d6-4?

 

[rancke]

There has to be a way to use the 1d6 by 1d6 matrix for this...

HG2 has 150 - 175 hours for jump duration., so you are looking for a random number of between 1 and 26 - to which you add 149, hmm - 5d6-4?

Average is 5½ hours too low.


Hans

 

[Fritz_Brown]

Of course, how closely can you know the time, anyway? It's all an assumption based on the ship's clock (and assumes the ship's clock isn't affected by jump). The local time will have *no* relationship to the local time where you left. And, gauging the precise time by star movements will be fraught with errors that will make 1d6 hours seem irrelevant.

Of course, if you're chasing or racing someone to that star system, then whether you're late or early means everything. :toast:

 

[mike wightman]

Average is 5½ hours too low.


Hans

Lol, how can it be too low when it clearly states 150-175 hours in HG2?

Ok, so the authors of both editions of HG are wrong - they can't do 7 x 24 either

 

[BytePro]

162.5 + d * pi * sqr(abs)

 

[Hal]

And here I thought I'd finally either found (or re-invented) a method to simulate +/- 10% per the official rules *rueful grin*. Of course, using a d10 would have been just as easily accomplished...

 

[rancke]

And here I thought I'd finally either found (or re-invented) a method to simulate +/- 10% per the official rules *rueful grin*. Of course, using a d10 would have been just as easily accomplished...

The two methods I mentioned above are both pretty close to to canonical 10%. Especially if you consider that 10 is a round number and may "in reality" be 9 or 11%.


Hans

 

[mike wightman]

10 could actually be the rounding for 6 to 14, so your true spread is anywhere from +/- 6% of 168 to +/- 14% of 168

Come to think of it is the +/- 10% a linear spread or a bell curve about the mean?

So now +/- 10% may only be 1 standard deviation from the mean of 168 hours?

 

[SanDragon]

A single die roll would have a linear probability and multiple dice rolled together a bell curve of probabilities.

 

[rancke]

Come to think of it is the +/- 10% a linear spread or a bell curve about the mean?

The various rules incarnations either don't say or make it a bell curve (T20 (and arguably MT)). So a bell curve it would seem to be, even if it is usually not taken into account.


Hans

 

[Hal]

The various rules incarnations either don't say or make it a bell curve (T20 (and arguably MT)). So a bell curve it would seem to be, even if it is usually not taken into account.


Hans

Page 92 of the IMPERIAL ENCYCLOPEDIA has this to say:

spent in jumpspace by rolling 1D
1 =6 days, 2 to 5=days, 6=8 days

That merely implies that 17% of the time (16.66%), the ship takes only 6 days in Jump space to arrive at its destination, and 17% of the time the ship takes 8 days to arrive at its destination. The remainder of the time (4/6th or 2/3rds) it takes 7 days.

Now I'm going to have to look more closely to see where the +/- 10% rule comes from.

 

[rancke]

Page 92 of the IMPERIAL ENCYCLOPEDIA has this to say:

spent in jumpspace by rolling 1D
1 =6 days, 2 to 5=days, 6=8 days

That merely implies that 17% of the time (16.66%), the ship takes only 6 days in Jump space to arrive at its destination, and 17% of the time the ship takes 8 days to arrive at its destination. The remainder of the time (4/6th or 2/3rds) it takes 7 days.

Which is why I qualified my statement about MT. It could be argued that this emulates a bell curve, but if so, it's a VERY crude one. The T20 rule, OTOH, is undeniably a bell curve.


Hans

 

[nDervish]

The various rules incarnations either don't say or make it a bell curve (T20 (and arguably MT)). So a bell curve it would seem to be, even if it is usually not taken into account.

Bell curve in MgT as well. "Regardless of how far the ship Jumps, it always stays in Jump Space for roughly one week (148+6d6 hours)." (MgT Core, p.141)

Of course, if we want to be picky, that should be 147+6d6 hours. As written, it averages 169 hours.

 

[Timerover51]

Hmmm, I forgot about the jump uncertainty principle. This would make coordinated convoys and fleet jumps a bit more difficult, as your ships would likely be arriving over a period of 2 or 3 days.

 

[HiverLord]

...assumes the ship's clock isn't affected by jump)

If Jump Space were to affect a ship's (presumably) electronic clock, it would also likely affect its computer, the life support (run partly by computer), the jump engines (ditto), the power plant (again, ditto)...
One can probably assume that the clocks wouldn't be affected by jump space (assuming no misjump, naturally), but I don't know offhand what canon is regarding it.

Of course, if it does the easy solution would be to have a few mechanical clocks (analog) on the ship. But using them (and coordinating them...) could open another can of worms.

 

[mike wightman]

It is my firm belief that the time spent in jump is determined when the jump is plotted and is known the the crew of the ship.

The ship crew are certain of their emergence time.

It is also my firm belief that ships in a convoy, jumping at the same time to the same destination, share the same time in jump. Otherwise the convoy in Twilights peak would never have worked as written.

 

[nDervish]

Hmmm, I forgot about the jump uncertainty principle. This would make coordinated convoys and fleet jumps a bit more difficult, as your ships would likely be arriving over a period of 2 or 3 days.

I've seen a mention in another conversation here on COTI that ships which jump together and share their jump plot will arrive within 2 hours of each other. From context, I believe that it was probably canon, but I can't find it offhand to cite chapter and verse.