Merchant Ship Design (and some economic ramblings)

[Vormaerin]

Guess today is my day to post wall of text posts. There's been a lot of threads roaming over various aspects of ships and the Third Imperium setting that have prompted me to want to put down my thoughts more centrally, where they are the actual topic of the thread and not derailment So this thread will have a bit of setting speculation, then I'll actually get to the point about how I think merchant ships would actually be built, unlike the adventurer specials that are generally published. Of course, adventurer specials are what we need as gamers. No one is suggesting the PCs play literal space truckers who live normal lives.

The merchant ships in the core rules and high guard are generally designed for player characters and free roaming sketchy tramp traders in general. They are sort of jack of all trades ships with additional capabilities and lack of specialization that commercial ships would likely avoid. Commercial businesses are quite focused on cost efficiency. They aren’t going to pay for civilian grade sensors instead of basic sensors unless required by law or minimum safety. They aren’t going to have weapons unless they pay for themselves in quantifiable reduction in lost revenue. And so on.

The problem for ship designers is that there are a lot of unexplored elements of the status quo, which means a lot of how ships are designed will be determined by the assumptions each particular table makes about how the setting works.

For instance, how common is piracy and how does it work? Do pirates attack ships often enough to be a concern? And, if so, do they do so in ships that a merchant could reasonably fight off if armed? When they do attack, are they just stealing cargo if the merchant surrenders? Or are they stealing the entire ship and/or killing the crew and passengers? If they just steal cargo, merchants aren’t going to bother going armed. They’ll just have insurance and surrender as soon as it becomes apparent that escape isn’t possible. If they steal the ship, is it ransomable for less than the cost of effectively arming the entire fleet? If they are murdering people, is it even worth going to that area at all?

 

[Vormaerin]

Another question is how common is commercial space travel. We live in a world with enormous amounts of commercial travel. But space travel in Traveller is extremely slow. If you want to take a week long vacation or business trip from America to Europe, it's maybe a day of travel each way, plus your stay. In Traveller, if you are on Planet America and need to spend a week on Planet Europe, it’s probably 22 days or so you will be away. It is also very expensive, though we don’t have enough information to say just how expensive. A high passage is a month and a half to two months wages for a ship’s pilot. A first class airfare to Europe is like a week’s wages for a commercial airline pilot (ignoring that they’d probably get courtesy flights). But we don’t really know how much normal folks make to judge.

If space travel is common, it will mostly be handled by dedicated starliners. If it is pretty rare, you’ll probably have some portion of cargo ships that take passengers similar to how free and fat traders are designed, even though most will be pure cargo vessels.

Further question which doesn’t affect ship design that much, but does change how things work overall is where is the highport? Which is going to be determined by how you do jump travel. Are incoming tradeships arriving anywhere along the 100d sphere around the mainworld? Or do all the ships from Planet A arrive in roughly the same area? If there is a pretty clear “this is where ships arrive from jump”, you may well have the high port, or at least fueling stations, out near that point. But if ships could be anywhere around the planet, those things will be located in orbit so they are centralized.

 

[Vormaerin]

Do you have a lot of destinations in any given system that will need regular trade? Does it make more sense for your commercial ship to be a big jump tender hauling a lot of smaller non jump ships that can be quickly swapped out at each stop, so the actual jump ship is making more jumps with less time ‘in system’? Or do you think the interstellar ships would all go to a central spot and shift their cargo onto local shipping, which is more space efficient but less time efficient.

These (and other things) are factors that will affect commercial ship design that ultimately are going to be different for each group. But there are some considerations that are consistent. And there are some things that are later introductions that would change assumptions built into older ships.

 

[Vormaerin]

Hull Selection

Unless you have some specific design constraint (say, cylindrical ships plug into standard space docks the best), commercial shippers are going to go with the most cost effective hull design. And that is “CLOSE”. Cargo freighters don’t need to maneuver in the atmosphere. They just need to be able to land at places that don’t have high ports. They aren’t going to skim fuel because that is super cost inefficient. It is dangerous, it takes time, and it tends to put your ship nowhere near the port. Which increases piracy risk and time in the system as you have to travel to the port in normal space.

Close hulls are able to land on planets and are less expensive than “standard” hulls. Merchant ships aren’t going to be armored, so the downside of close hulls isn’t a factor. They aren't that popular in ship design because PCs need to do crazy stuff in atmosphere as part of their adventures. But I think they'd be a lot more popular in non adventurer themed ships.


Power

A commercial ship does not want to pay for more power than it needs. It’ll have enough to run its ship’s systems + its maneuver drive at the same time. It’ll turn off the maneuver drive during jump drive engagement. If the jump drive rating is higher than the maneuver drive rating, then if it is a cargo ship, it’ll use “jump dimming” and get the extra power from running the ship’s systems on minimum during jump. For passenger liners, it depends on whether you think the ship’s paying passengers will tolerate jump dimming or consider it a relic of a low tech past. Power for any weapons the ship has will definitely come from dimming the main power.

If you think your passengers would be pissed off about dimming, you might just use batteries for that temporary boost of power. They are quite cost effective compared to a larger engine that may result in more crew being needed.

 

[Vormaerin]

Drives
An interstellar ship is probably jumping from 100d to 100d and just going to and from the port. So they are not likely to pay for more than 1 or 2G. It doesn’t make that much difference in the run from the 100d to starport and back. If you are designing an in system, not jump capable freighter, then you would want higher maneuver drives to cut those longer distances down below where it makes sense to micro jump.

Jump drives are also likely to be either rating 1 or rating 2, depending on intended usage. Ratings higher than 2 are very likely only on specialist ships as it starts to become quite uneconomical unless it allows you to jump straight from one high pop, high tech planet to another high pop, high tech planet without visiting the low grade stops in between. You'd need pretty high value cargo to justify the reduced cargo space on that kind of route.

Fuel
This is where new innovations would change old designs alot, imho. Fuel/Cargo containers are absolute game changers. IMHO, every ship would be built with Jump 1 fuel and all additional fuel in Fuel/Cargo containers unless it was custom designed for a specific route. This allows the ship to make jump 2 transitions when useful, but carry additional cargo when only making a jump 1 or micro jump. It does cost a bit of cargo space on Jump 2 transitions, but more than makes up for it in additional space on Jump 1s.

A 1000 ton cargo liner needs 100 tons of fuel per rating of jump. It only costs 5 tons of space to make your 2nd 100 tons of cargo into a fuel/cargo container. So instead of 500 tons of cargo at jump 2, you have 495. But you have 595 tons of cargo when making Jump 1. That's a trade off that would pay for itself very fast.

 

[Vormaerin]

Weapons
How much a merchant would invest in weapons depends on how dangerous you think the environment is. But if you don't need to spend a lot of time away from port and the worlds have even basic anti piracy patrols, you probably don't need a much if anything in the way of weapons. If you do, it is going to be defensive weapons that help keep you alive while you try to escape. Namely beam lasers. Blowing a pirate to smithereens is a job for a Q-ship, not a regular freighter. If piracy is bad in your setting, you'd also have to look at whether it is better to have an escort for your 1000+ ton freighters than trying to make them able to fight back effectively.

 

[Condottiere]

1.

2. How much energy does a light emitting diode strip consume?

3. Outside of attributed default hull cost overhead, fuel tanks are free.

4. As are cargo holds.

5. Spacecraft (components) have a higher potential value than most cargo, and are self motivating.

6. If in a hurry, rip out the jump capacitors.

7. Washing machines appear to have an intrinsic value; that of toilets appear to be vague.

8. If corsairs have an acceleration of factor four, send in heavy fighters to run them down.

9. Speaking of ticket prices, businesses can write off travelling expenses in their taxes, tourists can't.

 

[Vormaerin]

Fuel tanks and cargo holds are free, but they aren't interchangeable. Making them interchangeable is not free, but very, very cost effective.

 

[Arkathan]

My Leyland Buffalo and Knarr Class merchants on the first page of the Custom Ships thread are my contribution to freighter design.

 

[Geir]

I think the equation on page 163 of the 2022 core book is wrong. It should be

time = sqrt(2 X distance / acceleration).

Which means the whole table is wrong !

That's not a lot of time to get pirated.

Can someone double check the math please?

Remember that the time is based on acceleration to midpoint, turnaround, and deceleration, so it's sqrt(4 x distance/acceleration) which is the same as 2 x sqrt(d/a)

 

[Vormaerin]

I'm assuming there's a deleted post that the quote came from? Anyway, you *could* have merchants sprinting to the 100d limit and jumping with momentum. And therefore arriving with starting momentum. I think that would be considered reckless and dangerous, because you don't know what's going to be in your path when you come out of jump. And you probably can't jump with enough precision that you'd be sure that starting vector is more likely to help than hinder.

 

[Geir]

(yes that post disappeared - probably after he read the left half of that page)
The whole jump at zero velocity relative to your start point and emerge at the same is just a way to ignore all the factors you'd need to consider in actually conserving energy: like planetary orbital motion and relative star velocities. Just like we normally ignore that for any star dimmer than about a G6 V, the middle of the habitable zone will be within 100D of the star - and a multi-star system would be full of 'dead zones' or paths that wouldn't allow a jump to various systems at various times of the local year... too much math.

So just assume it's like the speed limit signs in a harbour area. Keep your speed below 5 mph (or the kph equivalent), not because you aren't capable of going faster, but because it's the speed limit.

 

[Vormaerin]

I just figure it is common sense because you can't see what's going to be in front of you when you emerge. Who says there isn't a 10k freighter a few thousand km straight ahead when you arrive at maximum thrust?

 

[AnotherDilbert]

Drives
An interstellar ship is probably jumping from 100d to 100d and just going to and from the port. So they are not likely to pay for more than 1 or 2G. It doesn’t make that much difference in the run from the 100d to starport and back. If you are designing an in system, not jump capable freighter, then you would want higher maneuver drives to cut those longer distances down below where it makes sense to micro jump.

Agreed.

Jump drives are also likely to be either rating 1 or rating 2, depending on intended usage. Ratings higher than 2 are very likely only on specialist ships as it starts to become quite uneconomical unless it allows you to jump straight from one high pop, high tech planet to another high pop, high tech planet without visiting the low grade stops in between. You'd need pretty high value cargo to justify the reduced cargo space on that kind of route.

Generally, the cheapest way to transport stuff long distances is with J-3 or J-4, as in what does it costs the shipping company to transport a Dt cargo from Rhylanor to Mora, regardless of shipping rates, according to my calculations.

According to Gurps FT most trade is between the large HiPop worlds, and it is massive amounts. As an example Mora would see something like 500 MDt cargo and 250 Mpassangers, with about 250 MDt to Fornice, 25 MDt to Trin, and 140 MDt outside the sector.

I guess we would see large mid jump ships on major trade routes, and smaller low jump ships feeding to a nearby hub? Perhaps with high jump ships using drop tanks for passengers?

 

[Vormaerin]

Ultimately, the problem is that we don't know enough about the Traveller economy. GURPS Far Trader is a pretty cool resource, but it makes certain assumptions about how trade works that I am not sure would hold up.

In particular, I don't know that the passenger levels would be that high. Space travel is dramatically slower and more expensive than air travel. But we don't actually know how much people make. Is starship pilot a good paying job the way airline pilot is? You would expect it to be. But if it is, then space travel is simply unaffordable for most people. And that's before you consider how slow it is. Having to spend 15+ days just getting to and from your destination before you actually get to do anything at your destination is pretty harsh. But maybe the prices we have are for last minute trips and cheaper tickets are available on pre-scheduled liners? Or maybe starship pilot on a free trader is a crappy paying job where you are expected to make up the rest of your wages with crew shares of speculative trade?

Same thing with freight. We only have the prices and costs for how marginal tramp trade works. (And those are designed around making PC free traders need to adventure to make a living) The economics of major cargo liners are likely not the same. On Earth, shipping long distances by water is much cheaper than any alternative. The trade off for shippers is that sailing slowly uses the least fuel per trip, but results in more trips than sailing faster. This is true in Traveller also, but the cost of speed (high jump) in cargo capacity are much harsher. Crew on container ships doesn't really get much larger with bigger ships (which is not really true in traveller) and the biggest bottleneck for trade is slots at the port, also favoring larger ships. Which is presumably still true in space, but without the luxury of taking your supermax ship just from Shanghai to Rotterdam.

But I assume we want a lot of space trade. So we need to apply ample doses of handwavium to the commercial shipping industry by assuming economies of scale not in evidence in the rules. And fully utilized the ship design rules to maximize efficiency. Virtual Crew, Robots, etc to keep crew sizes under control. Fuel/Cargo containers to let the ship flex capacity over distance, which makes higher jump ships more feasible. Consider whether a LASH style jump frame carrying lighters makes sense. It may make sense in space where it doesn't IRL if a fast tanker & lighter swap let's the big jump ship move faster (ie jump more often) and be able to flex between different types of lighters (cargo, passenger, gunship, fuel) depending on the upcoming leg of the run. But that depends on how much use the lighters can get in system and how efficient you can make the exchange process, given that you can't schedule very tightly with how jump drive works.

Jump 3 traders out of Rhylanor absolutely would happen. The ability to get to Equus and Gitosy would be enormously useful. But I am trying to figure out why anyone lets Somem languish with a class C starport? Jump 3 from Rhylanor and Jump 2 from Magash would totally be funnelling through there on the way to Mora. But Traveller sector design doesn't factor in trade at all. So you either say things like "Well, the Imperial Port that is open to regular travellers is C, but the commercial shippers have a private B port" or you adjust ship design to accept that crucial trade links just don't have refined fuel and maybe not even a high port for large ships. Or you run a lower trade, space travel is dangerous Imperium and don't assume that such a route would be used.

 

[Nelphine]

Yup, I ran into the same problem. Any world with a pop 9+ should completely overturn all the trade in the nearby vicinity, and redo all the starport codes leading to the next large population.

 

[NOLATrav]

Is starship pilot a good paying job the way airline pilot is?

We know from the Equipment chapter in Core 2022 that a “Good” standard of living (SOC 7) costs Cr1,500 per month, Cr18,000 per year. Starship pilots make Cr6,000 per month, Cr48,000 per year which equates to a “Very High” standard of living (SOC 10). Gunners and Stewards, both at Cr24,000 per year, can maintain a “High” standard of living (SOC 8). This presumes no time off but traditionally (in CT) a ship’s annual maintenance provided two weeks paid time off per year.

 

[Condottiere]

Plus board and lodging.

 

[Arkathan]

But I am trying to figure out why anyone lets Somem languish with a class C starport? Jump 3 from Rhylanor and Jump 2 from Magash would totally be funnelling through there on the way to Mora. But Traveller sector design doesn't factor in trade at all. So you either say things like "Well, the Imperial Port that is open to regular travellers is C, but the commercial shippers have a private B port" or you adjust ship design to accept that crucial trade links just don't have refined fuel and maybe not even a high port for large ships. Or you run a lower trade, space travel is dangerous Imperium and don't assume that such a route would be used.

Several factors apply in rating a starport per High Guard pg 69.
Sensors, Docking, Fuel availability, Commercial space, Residential space and Shipyard capacity.
You have to look at the single character profile as an aggregate.
Somem is logically a refueling stopover, so docking and fuel could be A rated, while having poor sensors, limited residential areas or rudimentary shipyard capabilities. It is up to the GM to determine whether the rating is an average or the least common denominator among ratings.

 

[Nelphine]

Right, the problem is, if you have 100000 tons of shipping coming through per day, it's always going to turn into an A starport. There's simply too much traffic to justify a low rating in any starport category, except a recent catastrophic event.