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MyGURPS - Using GURPS Spaceships In Traveller

Using GURPS Spaceships In Traveller

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I love GURPS Spaceships for 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.

The Traveller-Specific Design Tweaks only apply to an actual Traveller campaign. Everything else is available in any campaign I run, though the Ship Owner advantage assumes Traveller's starting wealth.

General Design Tweaks

Split Systems

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).

Most civilian ships will have a split Armor/Cargo Hold system in each hull instead of a full Armor section.

Vehicle Dock [Hull]

A vehicle dock is similar to a hangar bay, but it only accepts one specific vehicle; "a SM +8 shuttle is not specific enough, but "a Wilting Flower-class shuttle" is. This is not a true internal system -- it is a recessed area in the hull with which the smaller vehicle mates (think Serenity and its shuttles). As with hanger bays, vehicle docks may be combined to hold one large vehicle or split among multiple smaller ones. Docking time is the same for a vehicle dock as for a hanger bay, though there is no "launch rate" -- each dock can launch its vehicle in one minute.

If a vehicle dock is targeted in combat and no vehicle is present, use the dDR of the larger spaceship; a disabled system prevents future docking. If the carried vehicle is present, the spaceship's dDR does not protect it! Treat the attack as a general attack against the vehicle, usually against the front or central hull (work this out when designing the spaceship or roll randomly). The spaceship itself does not take any damage from this attack unless it overpenetrates.

Vehicle Dock Table

Capacity (tons)1.5515501505001,5005,00015K50K150K
Cost ($)1K3K10K30K100K300K1M3M10M30M100M

Traveller-Specific Design Tweaks

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. Firing a sandcaster is a free action; it requires no roll and does not incur multiple task penalties. "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.


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%.

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. This advantage may also be used to fund only the down payment on a ship, after which the owner(s) will need to make regular monthly payments.

Note that Ship Owner is not Signature Gear -- think of it more as a specialized form of Trading Points for Money (p. B26), except that it can never be turned into actual, "liquid" cash. If the ship is destroyed, the advantage is lost. Owners can have their ships insured (usually at a cost of 0.1% 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).

This advantage assumes $15,000 starting wealth, as in GURPS Traveller. Adjust the values proportionately for campaigns with different starting wealth. For example, in a campaign where average wealth is $20,000, all the values below should be multiplied by 1.33.

Point CostShip's ValuePoint CostShip's ValuePoint CostShip's Value

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.

I do not allow Ship Owner to be combined with the Signature Assets enhancement from GURPS Spaceships 2: Traders, Liners, and Transports. If anyone reading this wishes to do so (against my recommendation), please note that since Ship Owner is based on half the cost of Wealth, the value as an enhancement should be +40% instead of +20%.

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