Tactical Movement in Space Combat

[Ezra]

Originally Posted by Anaraxes

i don't know whether you're looking for a "realistic" answer, nor what sort of "reality" your game is set in. So it's hard to give an answer like "all ships begin combat moving at 5 hexes per turn directly toward the opponents' side of the map".

It's just the Traveller system. I'm not worried about "realistic"; the setting already has artificial gravity and reactorless thrusters. I just want to be able to run it without the game screeching to a halt.

[ericthered]

[QUOTE=Balor Patch;2316415]

Originally Posted by Ezra

Expect combat to involve fast passes rather than dogfights.

or to be fought from relatively unchanging distances.

[Fred Brackin]

Originally Posted by Ezra

It's just the Traveller system.

Tht narrows down the likely situations. Really only pirates will be matching course with other ships and your starting point is where they come in to laser (or possibly missile) range while doing that. Total speeds won't matter in such situations. Only the speed with which the pirate is approaching the merchnt.

In invasion scenarios the defenders won't go out very far to meet the invaders. Just out of range of the orbuital isntallations they're defending.

[Anaraxes]

Sounds like it's time for a trip to the basement.

The scenarios from Mayday are pretty freeform, but most commonly begin with ships on particular worlds (and so "stationary", at least with respect to each other). There's a couple that start with relatively small velocities (3 hexes/turn, where a "hex" is one G-turn worth of acceleration). There's a smuggling scenario where a patrol vessel has to stop and check a stream of incoming free traders for illegal cargo, so if the early traders manage to convince the patrol ship to build up a huge vector, it'll have trouble catching the later ones.

Brilliant Lances (a later GDW starship combat game for TNE) has both sides begin most scenarios "with any vector desired" (presumably figuring that ridiculous choices will demonstrate their ridiculousness, which is fine for playing around with the game, but less fine if you had some narrative purpose in mind for an RPG combat). Most notable exception was a "rear guard" scenario, in which the goal is for the attackers to get past the rear guard -- obviously pointless if they're allowed to start with any vector desired.

[Ezra]

It's makilng more sense now. I found this on p. 221 of GURPS Traveller: Interstellar Wars in the section "Maneuver Phase":

If the vector counter’s new position will be in the front arc of its old position, it may move a number of hexes up to the spacecraft’s sAccel rating (rounded down).

Here's the same rule from "Maneuver Phase" on p. 166 of GURPS: Classic Traveller:

On its turn to maneuver, a spacecraft may change facing and/or accelerate. A spacecraft may change facing so it faces any hex-side. Acceleration is performed by moving its vector counter a number of hexes in any direction to a maximum of the spacecraft’s acceleration. Round acceleration to the nearest G for this purpose.

So that's pretty clear for the Traveller system.

Part of what made this confusing for me is that the rules explain in different sections that a hex = 10,000 mph, that sAccel is measured in Gs, and that the ship moves a number of hexes equal to its sAccel, so if one hasn't memorized those statistics, it's difficult to connect the dots.

Thank you everyone who chimed in. That helped me a lot.

[Say, it isn't that bad!]

Originally Posted by Anaraxes

There's a fairly simple way to track movement with a couple of counters, seen long ago in GDW's Triplanetary and later in other games like Mayday.

Each ship has two counters, the ship's current location, and its current vector on the map, which is to say its future location if it just keeps moving -- some distance and direction from the ship. Acceleration moves the vector counter, not the ship, some number of hexes. When it comes time to relocate the ship, the ship moves to the spot the vector counter is on, while the vector counter moves the same distance and direction the ship does. (You might find it easier to use a temporary counter to mark the location of the ship; move the ship to the vector; then move the vector marker so it reflects the temporary counter on the other side of the ship.)

A ship's G rating can then be used to count hexes the vector counter moves on the map.

This is brilliant, I love this, and I had no idea this mechanic existed.

[Fred Brackin]

Originally Posted by Say, it isn't that bad!

This is brilliant, I love this, and I had no idea this mechanic existed.

It goes back to Mayday! in the 1970s. That was an award-winning game (as the cover noted) and this mechanism might be what it won the award for.