Although I was initially apprehensive about GURPS Spaceships (an e23 supplement), I quickly came to love its fast and simple system for designing ships and running them in combat. It strikes a perfect balance between detail and playability, and it's quite adept at simulating Traveller spaceships... with a little tweaking. I'd like to thank everyone on the SJG forums for their help, ideas, and suggestions. This page uses the suggestions for weapon outputs from David Pulver's JTAS article on the subject.
Note that this page is not yet finalized, as I learn more by building more Traveller ships. Until this notice is removed, content is subject to change. Last updated 1/18/07.
Design Tweaks
Split Systems
This is the one tweak which applies in any game I run, not just Traveller. Certain systems may be "split" to share a single space. For example, a system could be "Cargo Hold/Fuel Tank"; instead of a full 5% of the ship being devoted to one of these, 2.5% of the ship is devoted to each. Add the cost of both systems together and divide by two. If both systems are high-energy, a single power point will run them both; if only one system is high-energy, it still requires a full power point to function. If a split system is hit, make a single HT roll; either both are disabled or neither is.
The following systems can be split for half effect (round down in all cases): Armor (halve DR), Cargo Hold (halve tonnage), Defensive ECM (halve penalty), Factory (halve production), Force Screen (halve DR), Fuel Processor (see below; halve production), Fuel Tank (halve tonnage and delta-V), Habitat (halve occupancy), Hangar Bay (halve capacity and launch rate), Jet Engine (halve thrust and fuel consumption), Mining and Refinery (halve production), Open Space (halve areas), Passenger Seating (halve seats), Reaction Engines (halve thrust; delta-V is unchanged), Reactionless Engines (halve thrust).
Jump Drives
A J-Drive is bought as a normal Stardrive Engine. J-1 drives are normal cost, J-2 are 2x as expensive, J-3 are 3x as expensive, J-4 are 5x as expensive, J-5 are 8x as expensive, and J-6 are 13x as expensive. There is never a need to buy more than one J-Drive system, except as a backup. Only ships of SM +7 or larger can have J-Drives.
Each jump requires (number of parsecs jumped x 1.5) Fuel Tank systems of fuel. For example, a J-4 ship will need to install six Fuel Tank systems, all of which will be emptied by a full-range jump.
J-Drives require one power point to use, though it takes approximately twenty minutes to "charge up for jump." Allocating more power points will divide the time by the number of points (e.g., diverting four power points into a J-Drive will allow for a jump in five minutes.)
J-Drives are the only available form of Stardrive Engine. Jump Gates do not exist.
Maneuver Drives
M-Drives are bought as Standard Reactionless Engines; there are no other reactionless engines in Traveller. They are available as early as TL8 and provide 0.25G thrust at TL8, 0.5G thrust at TL9, 1G thrust at TL10, and 2G thrust at TL11-12.
Fuel Processors
Most ships will have a standard fuel processor. This is a Design Feature (p. 29) and does not count as a system. It can process one Fuel Tank system every two hours. The cost is equal to the cost of one Fuel Tank system.
Certain specialty crafts may have a dedicated fuel processor, which is bought as a Mining and Refinery system. It takes up a full space and requires workstations (on large ships), but can process one Fuel Tank every twenty minutes. Neither processor requires any power points.
Weapon Batteries
Ships can mount plasma weapons as well as any form of laser. Particle weapons are allowed as long as their output is 300MJ or greater. Ghost particle (meson) weapons are allowed as long as their output is 3GJ or greater. Guns (excluding grav guns) are available but uncommon. Missile launchers are very common. Conventional and nuclear warheads are available; antimatter warheads and warp missiles are not. All weapon options (e.g., Improved, Rapid Fire) are available.
In addition, ships can mount sandcasters, which are bought as missile launchers which actually fire exploding loads of crystals. Each load provides cumulative dDR versus lasers and UV lasers (only) equal to 1/4 the launcher diameter in cm. This dDR lasts for one turn, or indefinitely if taking Drift maneuvers. "Sand" loads weigh half as much as missiles (which gives them twice as many shots per battery) and cost the same $1M per ton.
Repulsor Bays are best represented as Defensive ECM. If the Defensive ECM applies solely against missiles, double its penalty to -4 per system. All other stats are unchanged.
Note that "spinal mounts" on larger ships should usually be bought as fixed Major Batteries, not Spinal Batteries. True Spinal Batteries will be more common on smaller craft, such as fighters.
Force Screens
Only the following two options are available. Normal Force Screens and Stasis Webs are only found as Ancient artifacts.
Meson Screen (TL10): Bought as a half-cost Force Screen. It only protects against ghost particle (meson) weapons. For simplicity, divide the dDR by 5 ahead of time when noting systems.
Nuclear Damper (TL10): Bought as a full-cost Force Screen and uses the rules on p. 32.
Power Plants
Fusion Power Plants are available at TL8 (with 20 years of endurance.) At TL9 they can be installed on ships as small as SM +7. TL8 ships below SM +10 and TL9 ships below SM +7 must use Fission Power Plants.
Super Fusion Power Plants are available at TL10 (with 100 years of endurance.)
Design Features and Options
Habitats: Many large ships will have Total Life Support in their Habitats, but it is just as common to carry food as cargo.
Design Features: All ships should have the Artificial Gravity and Gravitic Compensation features. Indestructible armor does not exist. Streamlined ships are often Winged, but it is not a requirement.
Design Switches: No switches are appropriate, other than those expressly covered by these rules.
Cost
In the open market, assuming TL10, multiply the final cost of each ship (and any parts needed to repair that ship) by 0.25 if TL8, 0.5 if TL9, 1 if TL10, 2 if TL11, and 4 if TL12. Further multiply the cost of any "mass market" ship (i.e., one produced in large numbers and freely available on the civilian market) by 0.75 -- this does not reduce its repair costs.
Many ship owners get by with older, worn ships. A ship in fair condition (-1 HT, -1 to repair rolls) typically sells for 40% of this cost, while a ship in poor condition (-2 HT, -10% dHP, -2 to repair rolls) usually goes for 10%.
Combat Tweaks
Ballistic Combat
David Pulver suggested the following changes in a forum post to make missiles and other ballistic attacks a little more balanced. It assumes that ships will maneuver heavily to minimize relative velocity, and that missiles are optimized for frag attacks instead of direct hits.
A missile set for proximity detonation has an armor divisor of (0.1); one set for a direct hit has no armor divisor. In addition, the tables on p. 59 are changed to the following:
Base Relative Velocity Table (mps) Scale Close Standard Distant 20-second turn 1 10 100 1-minute turn 1/3 3 30 3-minute turn 1/10 1 10 10-minute turn 0 1/3 3 If rendezvous 0 0 0 If engaged 1/6 1/3 1/2
Weapon Minimum Velocity (mps) Conventional gun 1 Electromagnetic gun 2 Grav gun 5 Missile, TL7-8 1/3 or 1* Missile, TL9-12 1 or 2* Missile, Super 10 or 100* Missile, Warp 180,000** * Use the first, lower value if the target is at Point-blank or Short range, or if the maneuver the attacking spacecraft took last turn was anything other than Closing.
** Treat Minimum Velocity as 10 for damage purposes.
Character Tweaks
Ship Owner
The Ship Owner advantage essentially grants the character extra starting cash only for the purpose of starting the game with a ship. This money is unrelated to (and in addition to) normal starting cash, and can only be spent on a ship and any consumables necessary to the operation of the ship (fuel, ammunition, etc.) Multiple characters can take this advantage, pooling their wealth together to afford a more expensive, co-owned ship.
Note that Ship Owner is not Signature Gear -- think of it more as a specialized form of Trading Points for Money (p. B26). If the ship is destroyed, the advantage is lost. Owners can have their ships insured (usually at a cost of 10% of the ship's value every year), but that does little good if the ship is lost doing something not covered by the insurance plan (i.e., anything dangerous).
Point Cost Ship's Value 5 75K 6 100K 7 130K 8 180K 9 240K 10 300K 11 360K 12 420K 13 490K 14 580K 15 670K 16 780K 17 930K 18 1.1M
Point Cost Ship's Value 19 1.3M 20 1.5M 21 1.8M 22 2.2M 23 2.6M 24 3.2M 25 3.8M 26 4.5M 27 5.5M 28 6.5M 29 8M 30 9.5M 31 11.5M 32 14M
Point Cost Ship's Value 33 16M 34 20M 35 24M 36 29M 37 34M 38 41M 39 50M 40 60M 41 72M 42 86M 43 105M 44 125M 45 150M +1 +25M Behind the Curtain: Ship Owner is essentially Wealth with a -50% limitation ("Only to be spent on a ship"). The entries on the table above were interpolated (as an exponential function) using the canonical values for Wealthy, Very Wealthy, Filthy Rich, and Multimillionaire 1 and 2. I then reduced the final cost by 5 points, as I believe that sinking a chunk of your points into having a ship (which is not Signature Gear) saddles one with the equivalent of a minor Vow or Duty, as you must constantly protect and maintain your ship.
Example: A Filthy Rich [50] character in Traveller enters play with 1.5MCr starting cash. Therefore, a level of Ship Owner which gives you a 1.5MCr ship would be the equivalent of Filthy Rich (Only to be spent on a ship, -50%) [25] + Duty (To Ship) [-5], or 20 points.
As written, the effects plateau after 45 points (effectively Multimillionaire 2). GMs who wish to allow players with incredibly expensive ships can continue the exponential progression instead, with every 25 additional character points multiplying the ship's value by 100. For example, Ship Owner [56] is the same as Ship Owner [31 + 25], and would thus allow a 1.15BCr ship.