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Astrogation - player aid.


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Sometime ago someone posted a topic about what a gunner actually did in traveller.

In a similar vein I was thinking about Astrogators. As I see it in role playing terms, when plotting a jump, the astrogator uses the computer to produce some sort of data of possible solutions (reflecting the level of computer on board), and then using a combination of knowledge and intuition (reflecting the level of his skill), he plots the course of the jump, crosses his fingers, hopes for the best and rolls the dice.

I have the germ of an idea which I would like to throw into the ring as to how one might use a player aid to visualise the process.

You will need to have this sample player aid in front of you before you go on:


The idea is that the 'data' referred to above is given to the player running the astrogator in the form of randomly generated dots (see player aid). The scale on left and right margins represents astrogators' levels.

The player's task is to plot a straight line from the left margin of the player aid to the right which crosses through as few dots as possible. To reflect Astrogation skill, the player is restricted to starting and finishing the line within the bands up to his skill level.

So using the example player aid, an Astrogator with a skill of '0', would only have the option of plotting a course from the '0' section of the left margin to the '0' section of the right margin. (see the black line). A skill of one would allow the player to plot a course in both the '0' and '1' sections in the margin (the red line) etc.

Each dot the line passes through would represent a negative modifier to the dice-roll made to ascertain whether there has been a misjump (or some other mishap).

I suppose a simple computer program could be written to produce these jump data tables and the Referee could have a sufficient stock on hand.

The density of the spread of dots could reflect the level of the ships computer (more sophisticated = fewer dots = easier jump).

As I mentioned initially this is just a germ of an idea, but I would be grateful for comments, suggestions for improvements etc.


Hmm, interesting idea

I like props for the players to use, it makes it easier for them to get involved with their characters IMHO.
I prefer your idea with the lines and aligning the segments with navigator skill...it looks more elegant, it would still be reasonably quick to do and it gives more permutations.

I agree that the 'look' of the data is important - but a ship's computer producing lines rather than circles would be more in keeping with what I'd expect a computer to produce.

Thanks for the input!

Could the jump engine rating limit the number of zig-zags (drive field modulations - nice use of technobabble - like it ;) ) that you can put in your plot?
Mmmm like it, Sigg.

I'm going to go back to the handbook and see if there are any other variables to consider over and above: Nav skill, computer level and jump engine rating...can anyone think of any more?

Course tape versus generate program?

Jumping to a system for the first time without a "jump rutter"?

Jumping into deep space.

Jumping to a specific world within a system that isn't on the normal course tape/generate log.
Very interesting. Some ideas for your consideration...

Use the circles to represent real space gravity topography intrusion into jump space but have a different set for each jump level. Ideally on transparency so you just overlay a number of cells equal to the jump number, though you could just have six different printouts each more populated. Another benefit of transparencies is (if you make them square) you can rotate them and have that many more different views. At least I've always felt farther jumps should be trickier than short ones.

To show computer assistance, a computer should be able to do the plot quicker and/or easier but it is still supposed to be possible to do it without. So maybe add or subtract an overlay for the difference between the jump number and computer number. Or change the side scales for the computer benefit of more computer than jump.

I like the simplicity of the line idea but would prefer a curve. And the notion of drive field modulation and skill limiting the deviation is good too. So perhaps the thing to do is let the player draw a plot. The number of points in their plot could be a factor of the skill level or task check or whatever, and the total deviation from one point to the next could be related. After plotting their points connect them with a smooth line.

This represents ideal plots. To add the random factor drop another overlay on after the plot is made.

For situations of increased misjump chance (less than 100d, less than 10d, unrefined fuel, drop tanks, hull damage, whatever) add an appropriate number of extra overlays, again after the plot is made.

Now count up the total times the plot intersects a circle. This shows the deviation from the average and if the deviation exceeds a certain limit the ship has misjumped.

Maybe there's something in the above that'll work. Very interesting concept ravs and some good ideas everybody else.
A rutter was a ship navigator's diary and journal. It included charts and crucial navigational data that were often considered to be trade secrets.

IMTU navigator/astrogators keep such journals for jump data and guard them jealously.
I did some equations for variable jump durations a while back. Some folks didn't like them as they weren't canon as far as travel time (i.e. if you have a Jump-2 drive and are only going Jump-1, it cuts your travel time according to these calculations). If you take the Distance Travelling and Jump Drive out of the Travel Time Calculation, it makes it canon (I think). Someone also suggested throwing in an exponential in there somewhere, but I never knew exactly where to put it. I designed this more for playability (the player playing the navigation gets to use a calculator unless the computer is down).

I hope this helps,


((( B + G + R + C ) X P ) / D ) X F )

Base DC ( B )

Fuel Used ( F )
2 - Unrefined ( Cr100 )
1 - Refined ( Cr500 )

Distance Traveling ( P )
In Parsecs

Jump Drive ( D )
Rating of Drive (i.e. J-5 drive, J-2 drive, etc...)

Gravity Disturbance ( G )
+15 - less than 10 diameters from gravity well
+5 - less than 100 diameters from gravity well
+0 - more than 100 diameters from gravity well
-10 - more than 250 diameters from gravity well

Destination Circumstances ( R )
-5 - Familiar Destination (negates other destination circumstances)
+5 - Fringe/Frontier region
+5 - Deep Space (empty hex)
+10 - Uncharted region

Other Circumstances ( C )
+15 - No Functioning Ship's Computer
+5 - Rushed, under fire
+5 - per month past annual maintenance
+5 - Using old Jump Tapes
-5 - Extra time taken for calculations and system cross-checks
-5 - Using a manual astrogation plotter to cross-check
-5 - Using recent Jump Tapes
+2 - Drop tanks used to fuel jump
+2 - per field repair since last annual maintenance
+1 - per major damage since annual maintenance
+1 - per rebuild of drive (as opposed to full replacement)

((( B + R ) X P ) / D ) - A

Base Time ( B )
147 hours

Randomizer Dice ( R )
roll 6d6

Distance Traveled ( P )
In Parsecs

Jump Drive ( D )
Rating of Drive (i.e. J-5 drive, J-2 drive, etc...)

Astrogator's Modifier ( A )
This is the number the Astrogator's Jump Plot check succeeds by divided by 5.
Thanks for the extra input everyone. I think I'm nearly there. I like Sigg's idea of rutters, so if one wanted to incorporate that aspect, then the Astrogater just keeps the chart and can use it to plot further jumps between the same systems (with the same ship?)

I guess for me the object is that the system has to be simple to create and fast and easy to use, otherwise the role playing breaks down as people obsess about little details in the player aid.

Here is a prototype excel spreadsheet (that doesn't use macros) that produces the jump plots.


To generate a new plot, press F9.

You can play around with the density that you want by increasing or decreasing the data ranges. So for example if you wanted a jump 2 calculation to be more difficult, you could increase the data ranges. If you wanted to make it easier to calculate jumps in sparse systems you could decrease the data ranges.

I would be grateful if someone would playtest it with their traveller group and give me some feedback. Unfortunately the last time I played traveller was over 20 years ago - I don't have a group to game with but I enjoy the mechanics and writing adventures.

Oh, just one thing - it may not work (it uses the RANDBETWEEN function in excel) if you have not activated the Analysis Toolpack add-in on Excel. To do this go to Tools/Add-ins and check the Analysis toolpack box.

Now...I must get back to the latest Harry Potter book!



P.S. - I think that many of the factors in Dameon's system could be incorporated into the spreadsheet which could perform the calculation.

Hey ravs,

Neat idea you've come up with. I'm going to have to try that out. When I first came up with that equation, when T20 first came out, I was altering the Jump paradigm for MTU a bit. I don’t think Jump Tapes are canon anymore. They were in CT only I think. There’s nothing in any books about 250 diameters out makes a jump safer. Using Distance Travelled and Jump Drive Rating in the equations aren’t canon at all. I’m not sure if using Unrefined fuel doubles the DC check or not, in fact, now that I think about it, that doesn’t sound right. I can’t remember where I saw something similar to that, tho.

So she’s gonna need a little work. Shoot me an e-mail if you’ve got any questions. I’ve got a ton of source material (although very disappointed that I’ve lots my copy of DGP’s Starship Operator’s Manual)