CT Only: TTB Vector Movement

[Supplement Four]

I've actually never used the vector movement system described in TTB and LBB2. My introduction to Traveller was via Starter Traveller, and I've been in love with the Range Band system ever since.

Tonight, for kicks, I thought I'd slog my way through those rules. They're kinda light, and they don't really address the issue of changing vector when your "Speed" exceed your M-Drive rating.

Example B (text on page 73, diagram on page 75) explains a vector change. But, the example isn't that great because the ship's original vector is 75 mm @ 90 degrees. With a M-1 drive, the ship is moving so slowly that diverting course to the point where the second vector would take you (75 mm @ 180 degrees) means that the ship can change course immediately and be on the new vector of 106 mm @ 135 degrees.

What I was looking for was a course change once the ship has built up a lot of momentum.




VECTOR MOVEMENT

I assume it works like this. Let me know if I'm off the mark. I don't see a good example to support this.

A Free Trader accelerates a full thrust for 10 rounds. That's full thrust for 10,000 seconds, producing a vector of 1 meter @ 90 degrees.

-- Accelerating at full thrust for one more round will produce a vector of 1.1 meters @ 90 degrees.

-- Decelerating at full thrust on round 11 will produce a vector of 900 mm @ 90 degrees.



The simple way to find the new vector is to figure the point if the ship does nothing (just coasts--doesn't accelerate or decelerate). We'll call this the working point. Then allow movement to any point within 100 mm of that working point. If you want, you can use a protractor and place it on the working point, drawing a sphere out to 100 mm radius around the working point. The new destination point can be anywhere within that circle drawn.

To find the new vector, simply connect the ship's starting point with the new destination point (that we created in the circle).

That's what we're talking about, yes?







GRAPH PAPER

I guess, if you didn't want to use string, a ruler, and a protractor to find vectors, you could use some tight graph paper and restrict movement only to line intersections, making each line intersection represent 100 mm. The problem with this, of course, is the ability to game the board by traveling the diagonals instead of the other lines.







PLOT NOT NEEDED!

I've always found TTB vector combat system overly fussy. There's no real need to go to all that trouble plotting ships. Since there is no facing rules used in this combat, all you need to know is one of these two things:

-- Is your target at range of 250,000 km or more? If not, then no modifier. If so, then use -2 to hit.

-- Is your target at range of 500,000 km or more? If so, use -5 to hit.

That's why I find the Range Band system as my preferred system. It doesn't matter what direction your enemy is attacking you from. All you really care about is where your enemy is--at one of three ranges: Less than 250,000 km, between 250,000 km and 500,000 km, and past 500,000 km.






TO PLOT OR NOT TO PLOT

Where I think a plotting system is needed is with complex combats. If there are multiple ships in the combat, then using the Range Band method can get sticky.

Or, combat can get complex when there are battlefield hazards. Using the Gravity rules for a nearby planet is a good reason to use the vector system and plot combat.

I could see the vector movement system being quite fun if combat takes place in a dense asteroid field (should be plenty of room unless high vectors are used, making the ships have little maneuverability) or in the rings of a planet.

 

[Carlobrand]

...The simple way to find the new vector is to figure the point if the ship does nothing (just coasts--doesn't accelerate or decelerate). We'll call this the working point. Then allow movement to any point within 100 mm of that working point. If you want, you can use a protractor and place it on the working point, drawing a sphere out to 100 mm radius around the working point. The new destination point can be anywhere within that circle drawn.

To find the new vector, simply connect the ship's starting point with the new destination point (that we created in the circle).

That's what we're talking about, yes?

...

Sounds right to me. My first exposure to vector mechanics was Mayday. I like the three-counter plot, personally.

Bands work well for two ships or one (spatial) dimensional combat. That covers the vast majority of role-playing encounters: you're heading somewhere or running away from someone. Things only get wrinkly where there's a second (spatial) dimension involved: you jump insystem with the world dead-ahead but a potential opponent at the edge of your sensors and closing from the 3:00 position, say. Do you dive for the world, run from him, or do a little of both? Not something easy to capture in one dimension.

 

[tim_manley]

When we used to do it we just used vector math. So you travel at one heading for 3 turns at 3G meaning you're 9G velocity, change to new head, at 3G, then use the vector math to plot your course -- i.e. travel 9g at your old heading, then 3g in your new heading....

But, I was studying physics at the time. Also why my players wanted to move to the rang band method after the first few months of playing in the campaign I wrote up in the MTU forum.

 

[nats]

Thats how I used to do it but I used inches to represent Gs instead of 100mm because 100mm per G soon gets unwieldy. You can just about manage fighting a small battle on a single table using an inch per G I found. And its pretty good fun, especially when you throw some moving asteroids/gas giant rings into the mix. In open space the movement is pretty irrelevant for the most part and range bands would probably be just as sensible, although not as much fun visually. If weapon bearings were important the vector movement might have made more sense.

 

[mike wightman]

1cm for 1g works too - and it keeps it metric to boot

If you do include weapon arcs you learn very early to keep your total velocity quite low to allow for manoeuvring to bring weapons to bear.

 

[tim_manley]

I used 1mm per G and colored pencils for each separate track. With missile salvo's, fighter's launched, multiple ship combat, it gets pretty unwieldy pretty quick, and the colored pencils fill up the butcher paper pretty quickly as well.