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Old 02-01-2022, 03:28 PM   #1
DaltonS
 
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Default [Spaceships] Translating CT ship stats to GURPS 4e

I'm looking for advice on converting old Traveller ship design stats to the new GURPS Spaceships format. Jason "RPK" Devine's MyGURPS rules for using GURPS Spaceships with GURPS Traveller were helpful but are mainly focused on creating new ships. I know a direct translation is impossible but some of the old components should be convertible into Habitat modules or smaller size systems. My current interest is in converting the Deep Space Station used in the Empty Quarter Sector so I can use it for my Bifrost Project set in the Sword Worlds subsector. Any help here would be gratefully accepted.
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Old 02-01-2022, 06:46 PM   #2
Anthony
 
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Default Re: [Spaceships] Translating CT ship stats to GURPS 4e

Honestly, I would ignore GURPS Spaceships and convert directly: hit points = (some constant)*(ship size)^1/3, DR = (some other constant)*(high guard armor factor)*(ship size)^1/3.
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Old 02-02-2022, 01:07 PM   #3
Anaraxes
 
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Default Re: [Spaceships] Translating CT ship stats to GURPS 4e

Which is more important to you: using the Spaceships rules, or having the ships match the CT stats (tons of cargo, number of passengers, fuel as range and percentage of hull, etc)?

If it's preserving CT abilities, then just design a ship that has the right stats -- write down the specs you've already got from CT in Spaceships format. If there's a system or two left over, fine. Just leave it empty. Not quite enough cargo space? Just make it bigger to match. (The CT rules themselves allowed a 10% margin of error in deck plans on top of using a convention for the size of squares that itself was off by about 4%. Absolute precision of conversion isn't really required, as the source data isn't all that rigorously precise to start with. Meanwhile, the Spaceship rules are all about scaling its 1-3-10 progression, not hardcore reality -- especially since the exotic armor materials and weapons don't actually exist.) Beware of just matching the names of weapons. In this option you've got to think about how they play out in the SS combat rules. Is a "laser turret" really a "laser turret"? Is a "major weapon battery" firing missiles a "50-ton bay", or does that erase targets too quickly or slowly?

If the goal is converting to use the Spaceships rules, you can design ships to fit the concept ("small freighter carrying both passengers and freight", "patrol missile corvette", "monstrously huge battleship with a BFG spinal mount") using Spaceships without detailed reference to the CT stats. But of course those ships might vary a bit, and so they won't all have exactly the same relationship and provide the same feel as the CT versions.

Third option is to use the CT rules for ships, and GURPS for the characters. You don't usually have PCs shooting at ships or vice versa, so you don't really need GURPS stats for ship weapons. (Ship weapons hit human? They die. Human shoots a weapon intended for use on humans at a CT ship? It bounces off; the "unarmored" hull starts at DR 60.) The question in this option becomes mapping GURPS skills the PCs have to CT skills, so you know how to "make a Piloting / Navigation / Engineering / whatever" roll called for by CT rules. But most of those are easy to do just with the names of the skills.

Here's PK (Jason Levine)'s notes on using Spaceships for Traveller.

Last edited by Anaraxes; 02-02-2022 at 01:11 PM.
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Old 02-03-2022, 07:38 AM   #4
DaltonS
 
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Default Re: [Spaceships] Translating CT ship stats to GURPS 4e

One thing that would be helpful would be GURPS Spaceships stats for the most common common Traveller ships so I could properly load the hangar bays and vehicle docks of vessels that would carry them. GURPS Spaceships is mostly mass oriented while Traveller ships are defined by volume so using the standard tonnages is out. Converting standard Starport Berths into hangar tonnage is tricky.
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Old 02-03-2022, 08:20 AM   #5
Fred Brackin
 
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Default Re: [Spaceships] Translating CT ship stats to GURPS 4e

Quote:
Originally Posted by DaltonS View Post
GURPS Spaceships is mostly mass oriented
Spaceships is entirely mass oriented. The use of SM (originally a linear measurement) to label what are completely mass-based ship size categories is unfortunate.

One answer is to use GT stats because GT tracks both mass and volume.

I believe the other one is to rebuild original Traveller ships from the ground up in Spaceships. The way I'd do it is to make the "fuel rule" be 2 Spaceships modules per J-number. So what was 10% of a Free trader in CT remains 10% of a Free Trader. This is simpler to me than other suggestions and I believe gives greater versimilitude compared to other more literal translation schemes.
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Old 02-04-2022, 06:53 AM   #6
Anaraxes
 
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Default Re: [Spaceships] Translating CT ship stats to GURPS 4e

I'd agree that Traveller fuel is best thought of as a percentage. Ships are mostly LHyd. I can't remember players ever caring about the actual mass of a ship, loaded or unloaded.

(You might have a scenario where they're trying to land on an ice crust or some such -- but that's a plot point, so whatever the weight of the ship in that gravity, the crust will inevitably happen to be of a convenient thickness for the material so as to barely support the ship, demanding extra safety measures -- or whatever the plot is demanding. The story's got nothing to do with meticulously calculating the mass of the ship and the shear force for a randomly-determined thickness of sea water ice to find out the ship and its crew break through and turn their ship into a submarine. Or die horribly, or whatever the consequence for being too heavy. The GM did know what that consequence was going to be if it did happen, right?)
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