[Peter Knutsen]

The reason all GURPS Spaceship are 20 modules big is simplicity, and ease of velocity/delta-V calculation (keep in mind, modules are based on mass, not volume, a huge departure from earlier GURPS projects. It's exactly why performance calculations are so extremely easier than they used to be).

But there's no reason why a larger ship can't have undersized modules installed. A SM+10 Exploratory Freighter could have 5% of its mass devoted to 100 SM+6-scale "moduler inserts", that can be bought and added piecemeal when in dock.

Also, ships can generally be much more modular in-world than the PDF posits, making module swap-outs easier, taking weeks or even only days, instead of the implied (IIRC) months. That's a world building decision.

The main problem with that is that undersized modules are sometimes not worth using. The Control Room of an SM+10 scale ship may already have so much sensor strength that there's no point in installing a vastly undersized Sensor-specialized module.

Also, why use GURPS Spaceships? There are reasons for using it, having to do with calculating performance statistics that are realistic, reasonable and objective, but if the setting has reactionless drives anyway, or almost-reactionless ones, the need to use GURPS Spaceships goes down drastically.


A few years ago I came up with a very simple point-based spaceship design system, which I unfortunately can't get at currently because of a hard drive crash, that looks more like BESM2 than it looks like anything else.

A bigger ship has more points to "spend", and you pay out points for STL performance, FTL performance, Endurance (the time you can be "out" before having to interface with a dock or tender ship, to resupply, replace filters and spare parts, and get serious maintenance), various weapon sizes, defence, sensors, stealth, and a huge bunch of special abilities for specialized ships troop carry, hibernation capacity, shipyard facility, labs, hangars and bays).

The idea is that spaceship design is always a tradeoff. You want to go faster? Then you must reduce offensive ability, or defensive ability, or something else. Or use a bigger ship, with bigger implying larger in size and requiring more crew. Or use a higher tech level ship (a low-TL Frigate might have 20 points, a med-TL 21 points, and high-TL 22 points).

The core idea is extremely easy to reproduce. The details only matter to the extent you care about special abilities, often quite exotic ones, and whether you want to encourage specialized ships and discourage generalist ones (such as the Star Destroyers of the Star Wars universe - I detest those because I really don't like do-everthing ships).

So that's one option. Give each player 20 Ship Points, and make a price list for STL Speed, FTL performance, Attack (or divide attack into target-size-optimized types, like I've done: small weapons suck against large targets, large weapons suck against small targets), Defence, Sensors, Stealth, Cargo and so forth. Each player buys whatever he wants. If a player wants more points, he must accept that his ship is bigger in size, making it more vulnerable to larger weapons, and increasing crew requirements and thus running costs (even if he doesn't have to pay for the purchase price of the (relatively larger) ship). Purchased Hangar means the ship has hangar space of some sort for another ship to dock in, perhaps another player ship that didn't buy any FTL performance. If this other ship doesn't have to purchase FTL performance then it has more points to spend on other things. Maybe it's faster STL, or it has very keen sensors, or a lot of stealth?

Ship performance upgrades are then in the form of extra points, bought with GURPS $ earned while playing, and having to decide what the extra points are spent on when you spend the money (you don't just buy a point that you then keep around until you decide, right out in the middle of nowhere, what you want to do with it. Not unless there's severe nanotech in the setting, anyway). The only problem here is, you'd have to make your system quite fine-grained so that upgrades can be done with reasonable frequency; mine isn't, so if I ran a campaigns and each PC got to upgrade his ship with 1 point every half year, the PC party would soon be able to pwn the entire galaxy.

Such a system can become very flexible, for instance you can offer special Modular capability at a very high cost, into which any ability can be "plugged in", or more Deducated Modular Slots that can only accept a subset of possible abilities, e.g. Any Weapon, or Any Sensor Or Stealth. Like GURPS' Modular Abilities, either in full form, or with some Limitations.

You just won't get the tie-in with real world units that you find in GURPS Spaceships or GURPS Vehicles (remember my comparison with BESM2), and putting in extra creation mechanics to thwart single-minded hyper-optimizaton makes the entire thing more complicated.

I built most of it, but then got stalled on how to price the ability to carry Riders, auxillary bay-carried vehicles larger than Fighters, such as the System Defence Boats of the Traveller universe (or the muchynbigger Battle Riders in C.J. Cherryh's science fiction setting). I didn't want it to be possible for a tiny Corvette, no matter how high-tech, to be able to carry multiple huge Battleships in "rider bays", but could not find a sufficiently simple way to price that and to limit unrealistic combinations. I eventually lost some interest in the project, and never got around to backing it up onto DropBox before my desktop computer crashed.


Another point-based option is to use GURPS. 4th Edition has the infrastructure to do everything needed for this, I'm sure. It'll also be reasnably balance from the get-go, unlike any point-based system you or I could make, which would require playtesting to balance it out.

Plus you have a wider selection of disadvantages to choose from. My PB Ships system only has a very few, like "Big" or "Bigger", or "Is High Tech" or "Is Ver High Tech", and then "Is Crew Intensive" which is what tends to set military ships apart from civilian ones. Lots of crew and thus higher salary/running costs, relative to other ships of the same size. I could add a few more disads to my system, but the structure is not supportive of that concept.

The point-scale is also finer-graded. Often to the point where if you have $ enough to purchase 1 CP worth of upgrade, you won't be able to find anything you want, so you save up your $ until you can afford what you want. Even if your players earn/loot/score enough $ to buy 1 CP worth of upgrade every month, their ships still won't become so awesome that they'll be able to pwn the entire galaxy after a few years.

The problem is, you get some the same issues as with BESM2 or with my (presently lost) system. GURPS point-based spaceships will "tie in" with real world performance units, speed, cargo volume, trip endurance, but it's very possible to hyperspecialize a ship for one thing, with no built-in game mechanical infrastructure to discourage that (the GM has to actively decide to set thresholds which it requires a ship UB to exceed, and it looks much better if he does that in advance, instead of doing it reactively to player choices).

But it can be done, and the system is there. I don't really have an idea how one would go about building a spaceship with the GURPS character creation rules, but there are others that can help you with that. One thing I do recall is that GURPs Bio-Tech for 4E has a writeup of a living ship or two, so if you're at a loss and can't get help here (which would be highly unlikely) you can look at the Bio-Tech writeup to see how GURPS does it.