Main Mount Weapons

At Muan Kwoyen, Albadawi used the bulk of his “new model” battleships—capable of jump-3 and carrying spinal-mount meson weapons—to surprise the Vilani. Suddenly the Imperials faced numbers far greater than they expected. Worse, the Terran battleships poured long-range meson fire into the Imperial line of battle. The Imperials had never developed meson weapons of their own, and knew of them only from fearful ancient legends. Now the Core Fleet faced the mythical “certain death weapon” in bitter reality, as its proudest ships were destroyed by internal explosions. —Interstellar Wars.

As games evolve over different editions, legacy elements shift, mutate, and occasionally break or disappear altogether. These might be due to game-mechanical changes or setting-background changes, and might be intentional or inadvertent. For example, a spell or firearm that was wickedly potent in edition X might get nerfed badly in edition X+1, only to be restored to some measure of glory in edition X+2. Or an alien species or fantasy race that was utterly villainous in an earlier edition gets retconned into one that is admirable or sympathetic in a later one.

Traveller has seen plenty of these changes over many editions as well as translations into new mechanical systems like GURPS or Hero. Designers generally ensure a basic level of continuity, but sometimes things get lost in the shuffle. And perhaps the one area in Traveller most susceptible to incompatibility is starship design: these subsystems are usually very fiddly and it is not uncommon to find a design that worked in a previous edition does not work in a newer one.

I ran into this problem as I converted some older system defense boats and monitors into Mongoose Traveller 2e High Guard. While most elements translated fairly well, spinal weapons often posed a problem. In the Third Imperium setting, spinals are the apex ship weapons in a hierarchy that begins with small 1-ton turrets, moves up through larger barbettes to even larger weapon bays that range from tens to hundreds of tons in size. Spinals are larger still: generally thousands of tons in size, so big that they run the entire length of the ship and so dangerous they can destroy enemy vessels with one shot.

The Cause Rampant, a 60,000-ton Azhanti High Lightning-class frontier cruiser, returned to service in 1086. Note the new meson gun spinal which replaced the old particle acclerator.

MgT has two types of energy weapon spinals: particle beam and meson guns. Both weapons have been in Traveller since the original High Guard (1980). In the Traveller setting, meson weapons are a transformative technology able to penetrate the most advanced ship armor. The ancient Terrans were said to have defeated the much more advanced Vilani Imperium in part because the Vilani had no defenses against the new and devastating Terran meson weapons.

In MgT, spinals cannot occupy more than half the tonnage of their starship. The smallest particle beam spinal is a TL14, 2,800-ton model; the smallest meson spinal is a TL15, 6,000-ton unit. This means the smallest vessel to mount a particle beam spinal is 6,600 tons, and the smallest to mount a meson spinal is 12,000 tons.

The MgT rule is perfectly sensible from a game balance perspective, likely intended to prevent tiny ships from mounting weapons of incredible power. But older editions of Traveller allowed smaller ships to mount spinal weapons. For example, the TNE supplement Gilded Lilly 3: Out of the Darkness features a 5,000 ton Castle-class heavy SDB with a meson gun spinal.

Another change: in previous editions, going all the way back to the CT High Guard, much less powerful meson guns could be mounted in weapon bays as small as 50 tons. However, as Marc Miller worked on Traveller⁵ he evidently decided that he wanted to remove meson weapon bays from the game, at least for Adventure Class Ships of 2,400 tons or smaller. If this is correct, the change helps keep meson weapons special and out of the reach of most PCs. But this shift also potentially invalidates some older ship designs as well as the battlefield meson accelerator, a 15-ton ground-based weapon system that originated in CT Striker (1981).

While meson gun bays are available in MgT High Guard, they are presented as a “high technology” option not normally available in the Third Imperium setting. (A couple of the larger example starships, such as the Skimkish-class or Antiama-class carriers, do feature mesons bays, but it is unclear if this was an error or an intentional exception.)

But there might be another way to get meson weapons on smaller spacecraft. A large weapons bay in MgT High Guard is 500 tons, and as noted above the smallest meson spinal is 6,000 tons. That leaves a pretty huge gap between these two different mounts, and leaves space for a missing weapon mount category. 

As it happens, Traveller⁵ has a mount that falls between the two: Main Weapons, which are “larger than Bay Weapons, but fall short of the immense power of Spines” (T5 Book 1, 152). By introducing Main Weapons into MgT, we can mount meson weapons on smaller spacecraft while keeping with the retcons introduced by Traveller⁵.

Main Mount Weapons for MgT

Main mount weapons, sometimes called baby spinals or lances, are the largest mounts available to ships under 5,000 tons and resemble spinal weapons in several important ways, though they are not nearly as destructive as spinals.

The crew requirements for main mount weapons are 1 gunner per 100 tons of main mount weaponry. All main mount weapons suffer DM-2 when attacking targets of 5,000 tons or less, DM-4 when attacking targets of 1,000 tons or less, and DM-8 when attacking targets of less than 500 tons.

Main mount weapons use a number of Hardpoints equal to their tonnage divided by 100, rounding up. A ship can only mount a single main weapon, and cannot mount both a main and a spinal. A main mount weapon mount cannot exceed a tonnage equal to half that of the ship carrying it.

Main mount weapons are classed as Destructive, but multiply Damage by 50 rather than 10 as with other Destructive weapons.

As with spinals, main mount weapons can be of variable size. The Main Mount Weapons table shows the effectiveness of a main mount weapon at its Base Size (this is also its minimum size). For every multiple of the Base Size, the main mount increases its Damage, Power consumption, and cost by the amount shown.

Main Mount Weapons

Weapon	TL	Range	Base Size	Power	Damage	Cost	Max Size	Traits
Meson	13	Long	500 tons	+150	+2DD	+MCr250	5,000 tons	AP ∞, Radiation
Particle Beam	12	Long	300 tons	+150	+1DD	+MCr150	3,000 tons	Radiation

Meson main mounts ignore all armor.

Main mounts do not become smaller as technology advances, but instead reduce their Power consumption. Each TL improvement decreases Power consumption by -10% and increases the Cost by +10%, to a maximum of three increases or TL15, whichever is lower.

Postscript

Many thanks to the posters over at Citizens of the Imperium and the Mongoose Traveller forums for help with thinking through main mount weapons, in particular AnotherDilbert for offering his ship-design expertise.

Copyright Information

The Traveller game in all forms is owned by Far Future Enterprises. Copyright © 1977 – 2021 Far Future Enterprises. Traveller is a registered trademark of Far Future Enterprises. Far Future permits web sites and fanzines for this game, provided it contains this notice, that Far Future is notified, and subject to a withdrawal of permission on 90 days notice. The contents of this site are for personal, non-commercial use only. Any use of Far Future Enterprises’s copyrighted material or trademarks anywhere on this web site and its files should not be viewed as a challenge to those copyrights or trademarks. In addition, any program/articles/file on this site cannot be republished or distributed without the consent of the author who contributed it.

Materials produced by Digest Group Publications (DGP) are copyright © Roger Sanger. Any use of Digest Group Publications’ copyrighted material or trademarks anywhere on this Web site and its files should not be viewed as a challenge to those copyrights. Usage is intended to follow the guidelines announced by Roger Sanger on the Traveller Mailing List for preserving the overall Traveller milieu.

Flying Purple People Eaters

A couple of years ago I bemoaned the surprising lack of color illustrations of beholders from the AD&D period. After scouring my collection I found some support for a purple paint scheme.

Recently James Maliszewski called attention to a 1981 Dungeons and Dragons cartoon advertisiment illustrated by the great Bill Willingham, one of my favorite TSR artists from this period. And wouldn’t you know, we have yet another data point from this era supporting purple-hued beholders.

The old D&D comic ads are remembered fondly by many fans like myself. I am blown away that Jeff Dee and Willingham had pitched an official D&D comic to Gary Gygax himself, only to get shot down by “the Dragon magazine person, who just hated comics and everything about them and who said he looked into it and it’s not viable.” (Given the timing, this was probably Tim Kask or Jake Jaquet.)

In any case, given that Willingham would go on to originate some outstanding comics, such as Elementals and Fables, this seems like a colossal lost opportunity—and sadly, one of many from TSR in those years.

I will close with one of my favorite Willingham pieces, from the Monsters and Treasures Assortment (1980). Here’s a treasure worth risking your character’s life for:

Local Defense Forces and System Defense Boats

I was posted to the Sig-Delt-885 for a couple of years. Good little pig boat, an old Sentry class that we called the Salli Dell. And a good crew of spacers, though we mostly pulled duty in the outer system. Caught a couple of smugglers, chased off a few pirates. Even got fired on once by a twitchy Aslan trader. But mostly just got really, really good at Dingir Hold’em.

In Traveller, most worlds with a Population Level of 6+ and a Technology Level of 7+ will have some sort of local naval force for the defense of the system, as well as a base to support such forces. At the lower end of the tech levels these forces will be capable of interplanetary but not interstellar flight.

Determining Local Defense Forces

The GDW designers of the Fifth Frontier War boardgame (1981) used a simple matrix of Population and TL to determine the number of system defense craft protecting different systems. This matrix was reverse-engineered by different Traveller fans and eventually published in the T4 supplement Imperial Squadrons (1997) as a table of “SDB Squadrons.”

Chris Thrash developed a handy analysis of “Military Forces and Spending in Classic Traveller,” in which he suggests that the median Imperial system defense craft is about 2,000 tons in size, but might range from as small as a 100-ton small system defense boat (SDB) all the way up to a 50,000-ton monitor.

Thrash’s analysis also suggests that we could introduce some variability to the Imperial Squadrons table. Instead of determining a number of system defense squadrons, we can generate a total tonnage for the local defense force, which can then be assigned as desired by the referee.

First, roll Flux (1D - 1D) and consult the following table to determine the base tonnage of system defense craft. Then multiply this base tonnage by the appropriate system defense factor to get a total tonnage of defense forces.

Base Tonnages

Flux	Tonnage
-5	400
-4	700
-3	1,000
-2	1,400
-1	1,700
0	2,000
1	3,600
2	5,200
3	6,800
4	8,400
5	10,000

System Defense Factors

TL	Population
	6	7	8	9	A
7	1/10	1	5	50	500
8	1/10	1	5	50	500
9	1/10	1	10	100	1,000
A	1/10	1	10	100	1,000
B	1/10	1	12	120	1,200
C	1/10	1	12	120	1,200
D	1/10	1	15	150	1,500
E	1/10	1	15	150	1,500
F	1/5	2	20	200	2,000

For example, Wicker (Magyar 2728 A541843-C) has a system defense factor of 12. Rolling a Flux of 3 generates a base tonnage of 6,800. Multiplied by 12 produces a total defense tonnage of 81,600. This might represent 200 400-ton Guardian-class SDBs, possibly divided into four wings. The leftover 1,600 tons might be spent on squadron of 32 50-ton heavy fighters. Or perhaps Wicker could use some portion of this tonnage on a couple of light monitors with spinal weapons.

In my campaign the Wicker system also has a notable secondary world, Marston (F4346AB-9), which has just enough of a population base to support its own local naval forces. Rolling a Flux of 5 generates a base tonnage of 10,000, which multiplied by a system defense factor of 1/10 produces a total tonnage of 1,000. This might represent a single squadron of twenty 50-ton heavy fighters.

Wicker is a subsector capital on the edge of Confederation space and therefore a priority target for the Solomani. The primary challenge for defense planners is that the Wicker system has too many places it needs to protect: in addition to the mainworld and Marston, there are four gas giants. Although GURPS Traveller: Starships suggests that “it usually takes fewer than 20–30 SDBs to fully cover a single gas giant” (109), that’s a lot of real estate for 82,600 tons of system defense craft, which suggests the Imperial Navy probably maintains a guardship if not a full squadron on station in the system. Given that Wicker is the subsector headquarters for the Unified Army of Fugue, an Imperial squadron would probably be an AssaultRon.

Bases

It’s important to note that the defense forces generated above are under the control of the local system and not the Imperial Navy (Imperial Encyclopedia 32). And as Thrash notes, “All worlds with local planetary and colonial naval forces have their own bases to support them (Supp. 3, p. 40). These are not depicted on the standard subsector maps.”

If an Imperial Naval Base is present, it will command its own defense forces. Based on GURPS Traveller: Starports (2000), we can also develop tonnage estimates for the Imperial Navy bases that do appear on subsector maps:

Imperial Navy Base Defenses

Flux	Typical Base	Subsector Fleet HQ	Sector Fleet HQ
-5	4,000	20,000	200,000
-4	4,000	22,000	220,000
-3	4,500	24,000	240,000
-2	5,000	26,000	260,000
-1	5,500	28,000	280,000
0	6,000	30,000	300,000
1	6,500	32,000	320,000
2	7,000	34,000	340,000
3	7,500	36,000	360,000
4	8,000	38,000	380,000
5	8,000	40,000	400,000

The resulting tonnages may be a bit low for particularly important or strategic systems such as subsector capitals or depots. (A few monitors eat up a lot of tonnage!) I might consider multiplying the tonnage by up to the mainworld”s Importance rating. These system defense craft will generally be TL14 and 15 heavy vessels and will likely include multiple monitors with spinal weapon systems. An additional 1/8th of this tonnage will be available in fighter support.

For example, the naval base at Asorret (Magyar 2923 B403866-B ) is the headquarters of the Imperial 96th Fleet. Rolling a Flux of 4 indicates base defense forces of 36,000 tons. This might consist of five 6,000-ton light monitors, 30 200-ton Serpent-class SDBs, and 90 Rampart-class heavy fighters. And with an Importance rating of 2, these defenses might be as much as double these figures.

System Defense Boats

A 400-ton, TL15 SDB, typically used by the Imperial Navy for defense of sensitive facilities.

SDBs are one of the most common types of ships encountered by Travellers. In Classic Traveller, the iconic, TL12 400-ton Guardian-class SDB is detailed in Traders and Gunboats (1980) with additional information in Journal of the Travellers’ Aid Society #9 (1981). As both sources note, “A wide variety of system defense boats exist, ranging in tonnage from 100 to 1,000 tons, and in tech level from 8 to 15 and above.” The MT Imperial Encyclopedia (1987) increases this range from 100 to 5,000 tons.

This variation is certainly borne out by a quick survey of Traveller editions. In general, there are two archetypes that recur again and again: a boxy, 400-ton SDB similar to the Guardian-class, and a torpedo-shaped 200-ton SDB exemplified in CT Fighting Ships (1981); this is designated the Viper-class by Power Projection: Fleet.

We have canonical examples of the 400-ton SDB at every tech level from 11 to 15. Different editions assign different class names to these vessels. And given that these boats are notable for being readily modified with different armaments and configurations, the situation is probably confusing to inhabitants of the Third Imperium: in addition to Guardian, we have Sentry (TNE) and Dragon (GURPS and Hero). TNE also has a Shugukan-class, which I think is supposed to be Vilani for “Dragon.”

The TL11 Sentry is presumably a predecessor of the TL12 Guardian, and the Dragon (which might be TL13) is described as a “slight improvement on the earlier Guardian” (GT:Deck Plans 6). Further, we know that as of 1116 or so that Dragons “are still found in the Imperial Navy, but they have largely been replaced by more modern craft” (GURPS Traveller, 2nd edition). This might be the TL15 SDB statted out in the MegaTraveller Imperial Encyclopedia, which the MT Starship Operator’s Manual names Dragon (sigh) in the “Relative Size Chart” (58).

In any case, Mongoose Traveller 2e High Guard (2017) has designs for the two SDB archetypes: a TL15, 200-ton and a TL13, 400-ton boat. Because Magyar sector has a generally depressed tech level (no world exceeds TL14) and was once part of the Solomani Confederation, it seems more likely to harbor more examples of older, Solomani-influenced SDB designs.

Three canonical designs seem likely candidates: (1) the Solomani 300-ton “standard” SDB from Fighting Ships of the Solomani (2009), (2) the 400-ton Sentry-class from Assignment: Vigilante (1992), and (3) the 800-ton Farnez-class from T20 Fighting Ships (2003). All three are likely to be found on both sides of the Imperial/Confederation border in Magyar.

Standard Solomani SDB (SD-CS60). 300 tons (streamlined hull), 6g, no jump capability, TL-13, Model 7/fib. 9 tons fuel. 13 crew. 3 hardpoints. 0 tons cargo. MCr196.

Sentry-class SDB (SD-DS50). 400 tons (streamlined hull), 5g, no jump capability, TL-11, Model 5/fib. 16 tons fuel. 17 crew. 4 hardpoints. 74 tons cargo. MCr199.

Farnez-class SDB (SD-HS40). 800 tons (streamlined hull), 4g, no jump capability, TL-11, Model 5/fib. 24 tons fuel. 28 crew. 8 hardpoints. 57 tons cargo. MCr341.

Mongoose Traveller Designs

Since I have been playing with 2e High Guard, I wanted to try my hand at converting these three SDBs. Probably the most notable thing I discovered was that, without having to include a Jump drive and the attendant fuel tanks, you can end up with a lot of dead space—even after maxing out the armor and maneuver drives. (Most of the canonical examples had relatively low accelerations compared to what I ended up with in MgT.) Further, the number of hard points limits the number of weapons you can add: in many cases, I used small bays or barbettes instead of turrets in order to use up excess tonnage.

Standard Solomani System Defense Boat

The standard Solomani system defense boat is the 300-ton “standard” boat, a design that reaches back to before the Solomani Rim War. The standard boat is still built throughout the Confederation, with many examples in Magyar on both sides of the border.

Hull Points 132

Crew Captain, Pilot x3, Engineer, Maintenance, Medic, Gunner x6

Maintenance Cost MCr0.0163 per month

Purchase Cost MCr196

Standard Solomani SDB

TL13		Tons	Costs (MCr)
Hull	300 tons, Streamlined	-	18
	Reinforced	-	9
Armor	Crystaliron, Armor:13	49	18
	Radiation Shielding	-	7.5
M-Drive	Thrust 6	18	36
Power Plant	Fusion (TL12), Power 360	24	24
Fuel Tanks	12 weeks operation	9	-
Bridge		20	1.5
Computer	Core 25/fib	-	15
Sensors	Improved (Extended Arrays)	9	12.9
	Countermeasures Suite	2	4
	Enhanced Signal Processing	2	8
Weapons	Small Bays (fusion) x2	100	16
	Barbette (missile) x1	5	4
Ammunition	Missile Storage (60 missiles)	5	-
Armored Bulkheads	Power Plant	2.4	0.48
	Maneuver Drive	1.8	0.36
	Fuel	0.9	0.18
	Bridge	2	0.4
Systems	Fuel Processor (10 tons/day)	1	0.05
	Medical Bay x1	4	2
Staterooms	Standard x9	36	4.5
Software	Maneuver/0	-	-
	Intellect	-	1
	Evade/3	-	3
	Fire Control/5	-	10
	Library	-	-
Common Areas		8	1
Cargo		0	-

Sentry-class System Defense Boat

The Sentry-class SDBs were first built by a technical consortium on Dingir, prior to its reabsorption into the Third Imperium. The particle beam weapons package reflects an emphasis on reduced logistical requirements; missile resupply problems cannot affect the Sentry’s offensive punch. An official IDP (Imperial data package) design since 434, vessels of this class may be found in planetary navies of this tech level throughout the Imperium and beyond.

Hull Points 176

Crew Captain, Officer, Pilot x3, Engineer x2, Maintenance, Medic, Gunner x8

Maintenance Cost MCr.0166 per month

Purchase Cost MCr199

Sentry SDB

TL11		Tons	Costs (MCr)
Hull	400 tons, Streamlined	-	24
	Reinforced	-	12
Armor	Crystaliron, Armor:11	55	20
	Radiation Shielding	-	10
M-Drive	Thrust 5	20	40
Power Plant	Fusion (TL8), Power 350	35	18
Fuel Tanks	16 weeks operation	16	-
Bridge		20	2
Computer	Core 15/fib	-	3
Sensors	Military Grade	2	4.1
	Improved Signal Processing	1	4
Weapons	Small Bays (particle beam) x2	100	40
	Triple Turret (sandcaster) x2	2	3.5
Ammunition	Sandcaster Barrels (120 barrels)	6	-
Armored Bulkheads	Power Plant	3.5	0.72
	Maneuver Drive	2	0.4
	Fuel	1.6	0.32
	Bridge	2	0.4
Systems	Fuel Processor (20 tons/day)	1	0.05
	Medical Bay	4	2
Staterooms	Standard x11	44	5.5
Software	Maneuver/0	-	-
	Intellect	-	1
	Evade/2	-	2
	Fire Control/3	-	6
	Library	-	-
Common Areas		11	1.1
Cargo		74	-

Farnez-class System Defense Boat

The Farnez class of SDB is typical of the lower technology end of system defense. The design predates the Solomani Rim War, when it was still being produced by the Imperial Navy and many lower tech worlds throughout the Imperium. At 800 displacement tons the Farnez is larger than many standard SDBs yet is still effective at system defense, and continues to see use in the planetary navies of Magyar sector.

Hull Points 352

Crew Captain, Officer x2, Pilot x3, Engineer x2, Maintenance x2, Medic, Gunner x16, Administrator

Maintenance Cost MCr.0284 per month

Purchase Cost MCr341

Farnez SDB

TL11		Tons	Costs (MCr)
Hull	800 tons, Streamlined	-	48
	Reinforced	-	24
Armor	Crystaliron, Armor:11	110	40
	Radiation Shielding	-	20
M-Drive	Thrust 4	32	64
Power Plant	Fusion (TL8), Power 540	54	27
Fuel Tanks	16 weeks operation	24	-
Bridge		20	4
Computer	Core 15/fib	-	3
Sensors	Military Grade	2	4.1
	Improved Signal Processing	1	4
Weapons	Small Bays (missile) x6	300	72
	Triple Turret (beam laser) x2	2	5
Ammunition	Missile Storage (960 missiles)	80	-
Armored Bulkheads	Power Plant	5.4	1.1
	Maneuver Drive	3.2	0.64
	Fuel	2.4	0.48
	Bridge	2	0.4
Systems	Medical Bay x1	4	2
Staterooms	Standard x15	60	7.5
	High x3	18	2.4
Software	Maneuver/0	-	-
	Intellect	-	1
	Evade/2	-	2
	Fire Control/3	-	6
	Library	-	-
Common Areas		23.3	2.3
Cargo		57	-

Copyright Information

The Traveller game in all forms is owned by Far Future Enterprises. Copyright © 1977 – 2021 Far Future Enterprises. Traveller is a registered trademark of Far Future Enterprises. Far Future permits web sites and fanzines for this game, provided it contains this notice, that Far Future is notified, and subject to a withdrawal of permission on 90 days notice. The contents of this site are for personal, non-commercial use only. Any use of Far Future Enterprises’s copyrighted material or trademarks anywhere on this web site and its files should not be viewed as a challenge to those copyrights or trademarks. In addition, any program/articles/file on this site cannot be republished or distributed without the consent of the author who contributed it.

Materials produced by Digest Group Publications (DGP) are copyright © Roger Sanger. Any use of Digest Group Publications’ copyrighted material or trademarks anywhere on this Web site and its files should not be viewed as a challenge to those copyrights. Usage is intended to follow the guidelines announced by Roger Sanger on the Traveller Mailing List for preserving the overall Traveller milieu.

Freighters of the Third Imperium

A Type MK freighter.

So I graduated from LSP Commercial in ‘92 with an Engineering-3 rating, which got me on the Alderamin Bulker, a big thirty-grand superfreighter out of Shululsish. I thought I had it made: the pay was sweet, even though it was LingScrip. But nobody tells you how they cram the crew into those big ships. Or how damned boring eight years on the same route gets. We averaged twenty-two jumps a year, over and over and over again. If I never set foot on another freighter it’ll be too soon.

Shortly after I published my last post on “Semi-Essential Ships of the Third Imperium,” I realized that I had missed a few more canonical examples of large freighters. The CT supplement Alien Realms (1986) had deckplans for the 3,000-ton Tukera Type AT freighter. Power Projection: Fleet (2007) had brief details on the 50,000-ton Kobe-class bulk carrier. And Mongoose Traveller had a 30,000-ton Galoof-class megafreighter in Pirates of Drinax (2017). (I continue to be amazed by just how much goodness is packed into that campaign setting.)

After looking at the Galoof I wanted to revisit my freighter descriptions, in particular the ones derived from GURPS Traveller. I haven’t done much ship design for any edition, but CT, MT, MgT, and Traveller⁵ ship designs all seem relatively compatible. Some differences in game mechanics between these editions might result in subtle differences to layouts or configurations, but in general a ship designed in one of these editions can be readily dropped into another one.

But I really wasn’t sure about how similar GURPS Traveller ships would be to ones created in other editions. At a glance, the Galoof specifications seemed more-or-less in line with the 20,000-ton Bulk Freighter from Far Trader in terms of size, cargo capacity, and jump capability. 

Curious, I decided to break out my copy of Mongoose Traveller High Guard and build a series of freighters at different tonnages. My goal wasn’t to recreate a specific design but rather to develop representative freighters that would be broadly compatible with four canonical sources: The Traveller Adventure, The Spinward Marches Campaign, Far Trader, and Pirates of Drinax.

So what minimum specifications should apply to large commercial ships? The few canonical examples vary quite a bit in terms of tech level (ranging from TL10 to TL15) as well as jump capability (ranging from J-1 to J-4).

The good old Traveller Wiki has trade route maps for most if not all of the official sectors in Charted Space. Thomas Jones-Low created these using the formulas from Far Trader, which estimates trade volume between worlds using a model that draws from real-world economics:

The gravity model is so named because it is based on a decreasing function of the distance between two “masses,” just like gravity. In this case, “mass” indicates the size of an economy. The variables used in real-world gravity models are economic size, average wealth, distance and measures of the economies’ comparative advantage (20).

A review of the Jones-Low maps for the rimward sectors of the Imperium demonstrates that the highest traffic routes—the ones most likely to be plied by large freighters—are generally jump-3 in distance. I found only one jump-4 link in the entire Solomani Rim. This suggests that the biggest freighters working major trade routes would only need to be built to a jump-3 specification, though small freighters working less-trafficked or frontier routes might need jump-4.

I was initially surprised by this finding: I had expected that the biggest ships, funded by the megacorporations, would be built to the highest tech level and would have higher jump capacity, maybe jump-4 or even jump-5. However, this makes perfect sense when we consider the nature of the gravity model: as you increase the distance between two worlds you decrease the strength of trade connections. Jump-3 seems to be in the sweet spot where worlds have plenty of choices of trading partners that are close enough to form main trade routes. Going with a lower jump number reduces costs but more importantly frees up a great deal of cargo space by reducing the needs for fuel storage.

Using MgT High Guard, I designed nine different freighters. Borrowing from terminology used in GURPS Traveller, I assigned these designs to one of three different classifications: Freighters (1,000+ tons), Superfreighters (10,000+ tons), and Megafreighters (100,0000+ tons).

Creating a single spreadsheet for all nine designs certainly sped things along and helped me spot errors. Although my 30,000-ton superfreighter departs from the Galoof in several ways, it was extremely helpful to have an example to calibrate against as I worked through the designs.

I spotted a few notable things in the Galoof that I adopted for my own designs: for example, the ship’s power plant is just large enough to simultaneously power both the basic ship systems and the jump drive.

The Galoof contains a full complement of crew, and does not utilize the “reduce by two thirds” rule for Large Ships (High Guard 20). I’ve followed this practice, though reducing crew size would significantly reduce operating expenses while freeing up stateroom space for additional cargo.

Along similar lines, the Galoof design assumes that the captain, flight crew, and officers all have their own staterooms and everyone else bunks in a double occupancy cabin (High Guard 21). I was a little surprised that the Galoof had no low berths for replacement crew, but this would be an easy modification.

The CT rules (and I think just about every other edition) require one medic per 120 passengers, or on any starship 200 tons or more. The Mongoose Traveller rules, however, only require one medic per 120 crew and passengers. I just flat-out think this is a mistake: having an able spacer develop acute appendicitis two days into a jump would make for an incredibly bad time. And looking at the designs in High Guard, all ships 200 tons or larger seem to have a medic. So, in lieu of errata I’ll follow the CT rule in my own designs.

The Galoof has common space equal to about 90% of the stateroom space. This is considerably higher than the suggested 25% (High Guard 21). For my own freighters I used the 25% guideline instead.

Most freighters passing through sketchy systems are likely accompanied by patrol corvettes or destroyer escorts either owned or hired by the parent corporation. While the Galoof sports neither armor nor armament, here I followed the examples from Far Trader and CT in assuming that most freighters utilize at least a small number of their hardpoints. The most common armament appears to be a triple turret with beam laser, missile racks, and sandcaster. This is almost certainly for show: the sheer size of the larger freighters, and their enormous number of hull points, is probably deterrent enough. In any case, adding armaments creates the need for gunners, who I assumed would double as shipboard security.

In general, I found the High Guard design sequence fun to work with and probably a bit easier than the MgT 1e sequence. I noticed that in general, there’s not a lot of advantage within the MgT rules to build freighters at TL15 instead of TL12 or 13, even though that higher tech level should be easily within the reach of a megacorporation. TL15 reduces your power plant by about 25% and gives you a better computer, but I’m not sure the extra cost is justified. 

Nevertheless, most of the CT and GT examples of freighters appear to be built at TL15, so I designed a few of my examples to that standard along with TL12 and TL13.

Finally, a couple of notes on secondary craft. Although many Mongoose Traveller designs explicitly do not include the cost of secondary craft in their ship prices, I have done so for the examples below. I have also not included the cargo space available on secondary craft in the ship cargo totals, even though The Traveller Adventure takes pains to point out that secondary craft can be carried with their own cargo bays filled, and that extra space really adds up on a giant starship. For a 100,000 ton megafreighter with ten 95-ton shuttles, this could add another 722 tons of cargo: more than carried by a 1,000 ton freighter!

And with that, here are some representative freighter designs. Based on The Traveller Adventure, different commercial lines appear to utilize their own, proprietary ship classes. So while smaller ships often have standardized designs that are used across Charted Space, freighters probably exhibit significant variation in specifications depending on region and carrier.

Freighters

Freighters are commercial vessel of 1,000 to 9,999 tons used by interface, subsector- and sector-wide transport lines to provide scheduled freight service. Freighters are uncommon on Feeder Routes but are reasonably common on the Main Trade Routes that support tens of thousands to millions of tons of cargo per week.

Merchant lines able to afford such large ships often employ robotic cargo handlers such as the JP-3, Stevedore III, or Longshoreman models—all manufactured and sold by Naasirka.

1,000-ton Freighter. 1,000 tons (standard hull), Thrust-1, Jump-3, TL-12, Computer-20/bis. 14 crew. 304 tons fuel. 10 hardpoints. One 30-ton slow boat. 471 tons cargo. MCr264.83.

2,000-ton Freighter. 2,000 tons (standard hull), Thrust-2, Jump-3, TL-12, Computer-20/bis. 19 crew. 607 tons fuel. 20 hardpoints. One 40-ton slow pinnace. 983 tons cargo. MCr532.59.

3,000-ton Freighter. 3,000 tons (standard hull), Thrust-1, Jump-4, TL-13, Computer-25/bis. 30 crew. 1,212 tons fuel. 30 hardpoints. Two 40-ton slow pinnaces. 1,090 tons cargo. MCr875.26.

5,000-ton Freighter. 5,000 tons (standard hull), Thrust-2, Jump-4, TL-15, Computer-25/bis. 48 crew. 2,015 tons fuel. 50 hardpoints. Three 40-ton slow pinnaces. 1,888 tons cargo. MCr1,637.90.

Superfreighters

Superfreighters generally include commercial vessels in the 10,000 to 99,999 ton range. Superfreighters are too large to profit from incidental trade; their routes are carefully planned, sometimes years in advance. These large starships are rare on Main Trade Routes and uncommon on Major Routes, which support anywhere from up to a million tons of cargo and tens of thousands of passengers per week. Superfreighters are relatively common along the even larger Mega-Routes.

In addition to the Imperial megacorporations, several large mercantile lines operate superfreighters in Magyar. These include the Solomani-controlled Transstar, Solomani Shipping, and Solar Shipping. Most of the principal corporations of the Wuan Technology Association utilize superfreighters, as well as several Aslan companies engaged in trading in the sector: Faiekhas, Oakhowus, Reastirlao, and Tlasayerlahel.

10,000-ton Superfreighter. 10,000 tons (standard hull), Thrust-1, Jump-4, TL-13, Computer-25/bis. 70 crew. 4,040 tons fuel. 100 hardpoints. One 95-ton shuttle. 3,970 tons cargo. MCr2,794.10.

20,000-ton Superfreighter. 20,000 tons (standard hull), Thrust-2, Jump-3, TL-12, Computer-20/bis. 121 crew. 6,067 tons fuel. 200 hardpoints. Two 95-ton shuttles. 10,437 tons cargo. MCr5,138.06.

30,000-ton Superfreighter. 30,000 tons (standard hull), Thrust-1, Jump-3, TL-12, Computer-20/bis. 173 crew. 9,100 tons fuel. 300 hardpoints. Three 95-ton shuttles. 15,901 tons cargo. MCr7,200.40.

50,000-ton Superfreighter. 50,000 tons (standard hull), Thrust-2, Jump-3, TL-15, Computer-20/bis. 296 crew. 15,125 tons fuel. 500 hardpoints. Five 95-ton shuttles. 26,240 tons cargo. MCr14,075.20.

Megafreighter

Megafreighters, the largest commercial ships at 100,000 tons or more, are rare even on the Major Trade Routes. A few dozen magafreighters may ply the high-traffic Mega-Routes, which support several million tons of cargo and hundreds of thousands of passengers per week. Only one such route exists in Magyar sector, connecting Daibei and the Solomani Rim, running through Stansifer (3109), Nosret (2807), Guenivier (2505), Nahn (2403), and Seloo (2102).

In Magyar, megafreighters are generally operated only by a handful of the great Imperial megacorporations: Kreuta (the sector subsidiary of Tukera), Ling-Standard Products, Makhidkarun, and Naasirka.

Megafreighter. 100,000 tons (standard hull), Thrust-1, Jump-3, TL-15, Computer-20/bis. 606 crew. 30,250 tons fuel. 1,000 hardpoints. Ten 95-ton shuttles. 51,981 tons cargo. MCr27,673.87.

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