Vector Diagrams and Range Zones

Vector Diagrams

If zone maps don’t give you the feeling of satisfying space combat, you may want to sketch out vector diagrams. This approach is more complicated than standard movement—you will have to be aware of the various ranges between opposing ships as well as their relative speeds and bearings—but it can be a satisfying alternative.

A vector diagram represents each ship as a vector—an arrow whose length reflects the ship’s speed, pointed in the direction of the ship’s heading, positioned according to the ranges between the ship and the others.

Over the course of one or more exchanges, the ships will be moved along the length of their vectors; every so often, the GM or a player may extend, shorten, or redraw vectors to reflect changes caused by space maneuvers.

During play, the GM can set difficulties for tasks like tracking an enemy ship with the ship’s lasers, computing a firing solution for the ship’s missiles, or matching course with a bogie by identifying salient factors such as range, relative velocity, and perhaps bearing. Typically, firing at or maneuvering against a ship on a parallel course moving at the same velocity without acceleration faces Average (+1) difficulty; things get harder from there.

Range

• Contact: The target ship’s hull is in contact with yours. Most ship’s weapons will not bear on another ship in contact, particularly if the target is much smaller.
• Proximity: The target ship is sufficiently close to permit physical exchange via spacewalk or similar means. Point-defense weapons (e.g., guns) can be used. Ship’s ordnance (missiles and torpedoes) will not have a chance to arm, but drones may be launched normally.
• Close: The target ship is within visual range, and normal beam weapons are in optimal range. High-powered spinal mounts (i.e., large beam weapons mounted coaxially along the ship’s length) may not be able to bear on the target. Firing solutions for missiles and torpedoes are easily found.
• Medium: Sensors can easily distinguish features of the target ship. Torpedoes and missiles may fire.
• Long: Sensors can distinguish most of the important features of a target ship. Normal beam weapons are at a disadvantage due to attenuation. Firing solutions for missiles may be found, but slow-moving torpedoes will have a more difficult time hitting their targets.
• Very Long: Sensors can only identify the most prominent features of the target ship.
• Extreme: The target ship can be detected only as a point source, and is out of range of the ship’s weapons.

Velocity and Relative Speed

• Accelerating: The target ship is increasing its speed.
• Coasting: The target ship is neither gaining nor losing speed.
• Decelerating: The target ship is reducing its speed.
• Faster: The target is moving more rapidly than your ship.
• Matched: The target is moving at the same speed as your ship.
• Slower: The target is moving more slowly than your ship.

If you’re dealing with multiple ships, you can assign absolute velocities using the ladder, so a high-speed interceptor may be moving at Fantastic (+6) speed, while a bulk transport on a low-fuel transfer orbit may only be moving at Mediocre (+0) speed. Ships with high thrust can change speed faster than ships with low thrust; ships with high specific impulse can accelerate and decelerate over longer periods of time than ships with low specific impulse.

Bearing

• Converging Course: The target’s vector will converge on your ship’s course.
• Intercept Course: A converging course in which the two ships will come within range of each other at matching velocities and parallel courses.
• Collision Course: A converging course in which the two ships will come into proximity or make contact without matching velocities.
• Overtaking: The target’s vector will come upon your ship’s course from the stern.
• Oncoming: The target’s vector will come toward your ship’s course from the bow.
• Parallel Course: The target’s vector will maintain its distance from your ship’s course.
• Diverging Course: The target’s vector will diverge from your ship’s course.
• Escape Course: The target is ahead of your ship along the same vector and moving away.

Apparent Size

More massive or radiant targets will be easier to detect and target than low-mass or low-energy targets. Warships in particular will be prepared to rig for silent running, with drives powered down and energy usage minimized so as to be less noticeable to opponents. Conversely, drones fitted with transmitters at different frequencies may be used as decoys, fooling opponents outside of visual range.

Range Zones

With many ships in space combat, a useful, simple compromise between zones and vector diagrams is range zones. First, create a zone map consisting of eight to ten bands of space, and place markers representing ships and other space objects in them. At the beginning of each exchange, a pilot in each formation rolls Pilot. Beginning with the lowest roll, each pilot chooses to have their ship stand still, to move one zone in either direction, or to move a single other ship that has not yet moved. If you are using phased combat, this takes place in the piloting phase, replacing the Maneuver option.

At the end of this process, ships in the same zone are in visual range and capable of using extremely short-range weapons, like tractor beams or point-defense guns. Ships one or two zones away can fire beam weapons at each other, and ships three or four zones away can fire missiles or torpedoes at each other. A ship that is seven or more zones away from any other ship, or which moves off the edge of the map, has broken off combat.

Resolve beam attacks and other short-range weapons immediately. Resolve missile attacks immediately if the target is within two zones, at the start of the next exchange if within four, and at the start of the second next exchange if within six. Torpedoes are placed on the map as if they were ships, and they move using the gunner’s Shoot skill on their roll. Resolve a torpedo attack when it enters the same zone as its target.

In some settings, the acuity of ship sensors will affect its ability to acquire targets beyond a certain range. A reasonable rule of thumb is to use twice the ship’s Sensors rating as its range in zones, so Average (+1) Sensors detect reliably out two zones, Fair (+2) Sensors out to four, Good (+3) out to six, and so forth. Scale modifiers (see below) may affect detection range, and attempts at stealth or misdirection can be resolved as opposed rolls (e.g., Pilot versus Notice). Otherwise, just assume that the maximum detection range equals the maximum engagement range (six bands).