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jbennet February 18th, 2018 07:02 AM

400 dTon Subsidized Merchant Conversion
OK, I've started banging around with GURPS Traveller again and I started work on converting some of the older vessels to the ISW system. I know Spaceships is the hotness, I playtested it and liked it. But the ISW system actually feels like Traveller. Spaceships feels different. Anyway, here's a link to a spreadsheet I created which has the GURPS ISW Stats. Also, this spreadsheet has much (not all) of the GURPS ISW ship design for ships up to roughly 1000 dTons automated. Here are the things that aren't set up:

Crew: The directions in the book consistently produce higher crew numbers for me than the examples provided. That tells me their either only meant as guidelines or I'm doing it wrong. In either case, it's something I shouldn't automate (someone else who understands it could automate it, but I shouldn't).

Weapons: Turret/Fixed Mount only. Oh, and I still need to link the formulas into the bottom two turret slots. Still a lot of work to do on that tab, much of it requiring some pretty impressive Google Sheets skills. I've got them when I have the time to crawl through the formula documentation, but I don't have that much time at the moment (an ironic statement from someone planning to convert all the ships with GT3E stats he can find to GT4E, lol). Once I get to something with more than 1 turret with weapons on it, I'll fix it.

DESIGN NOTES: This is not a 1:1 conversion, though I did my best. I kept all stats as close to the original as possible except for cargo, which is where all the slop ended up. Specific changes include:
Engineering was converted as a workshop.
There are 2 sickbays, one for each medic.
This version currently has two armed turrets. That was largely to test that my code worked.
The mass of the launch is it's lMass, not eMass.
The cargo bay is a full 100 dTons bigger. I'd appreciate someone looking over what I've done and making sure I didn't make any gigantic mistakes.

400 dTon Akkigish Subsidized Merchant

Brandon C February 18th, 2018 08:27 PM

After cargo space and fuel, the components that take up the most space on ships under 1000 tons are staterooms and small craft. GT bridges are also smaller than CT bridges.

Does GT:ISW reduce available space if streamlined? Normal GT did.

jbennet February 19th, 2018 07:42 AM

Well, as far as I can tell from the rulebook, no it does not. There's an increase in hull area (and corresponding increase in hull weight, armor weight, and armor cost), but no space penalty. I've matched staterooms and small craft exactly. I guess it just picks up an extra 100 tons of cargo space.

Brandon C February 19th, 2018 12:33 PM

Yeah, the streamlining penalty generally offset the lack of powerplant fuel, bridge volume and computer volume.

IIRC, GT:ISW was a 4e book, which is why I passed on it. So I'm not certain what is in it.

jbennet February 19th, 2018 07:36 PM

After doing a bit more digging, I believe I have found the major design assumption that changed. Under the ISW rules, M-Drives all deliver 200 stons of thrust for 20 MW of power. Under 3E rules found in GT:Starships, M-Drives deliver differing amounts of thrust based on TL. Streamlining was 20% of hull mass (so 80 dtons), but I was still missing another 20 or so dtons of extra cargo space. If I use 3E stats for the M-Drive (40 stons of thrust for 4 MW of power), I get 212 dtons of cargo, minus the 80 tons for streamlining makes 132 dtons vs. 146 dtons. That's much closer to the 3E stats. Since I like the idea of M-Drive thrust varying by TL (it only makes sense to me that as the tech advanced, one of the stats would move: cheaper, more powerful, more efficient. M-Drive tech did none of those things in ISW), I'll probably port over the 3E chart. I will include a note in the spreadsheet indicating which drive to select for ISW stats.

Brandon C February 20th, 2018 06:40 AM

Do any of the other classic Traveller designs appear in GT:ISW? If so, see what difference they have. This could help on further conversions.

jbennet February 24th, 2018 04:50 AM


Originally Posted by Brandon C (Post 583024)
Do any of the other classic Traveller designs appear in GT:ISW? If so, see what difference they have. This could help on further conversions.

They've got a 200 ton free trader. It's the Beowulf with Jump-2. It has better sAccel, Jump-2, and 18 tons of extra storage. Though it does have 6 fewer Low Berths though.

BRJN August 25th, 2019 10:34 PM


Originally Posted by Brandon C (Post 583024)
Do any of the other classic Traveller designs appear in ISW?

No. ISW spends its space on designs common in its historical era.
Some of them can be seen as 'backdated' versions of the common ships.
Besides the J-2 Beowulf, there is a 100 ton Vilani ship that could become the Type-S scout/courier. Two potential Patrol Cruiser replacements (400 tons; the Vilani ship is a police cruiser, the Terran is a raider) are described. A long-enduration exploration ship could be the 'forefather' of the Lab Ship.

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