Trade volume in the Marches

[Carlobrand]

(Prefix? What the heck's a prefix?)

Anyway, I'm playing around with figuring out trade volumes for the Marches. There's GURPS, but I'm not completely satisfied with that. Works for the most part but breaks down with extremes and some of the GURPS underlying assumptions are different from CT: for example, their ships can charge per parsec, which gives them a big advantage in calculating multi-parsec trade. And I'm not entirely convinced by that gravity model: sure, that 200-pop mining colony's GWP's going to be almost entirely trade, but even a small colony on a relatively earthlike world's going to be meeting a fair portion of its own needs from local resources, so the idea that they're importing everything from their big neighbor's a bit odd to me.

(Cargo shipping costs are about a third to a half what they are in CT, and passenger fares are about a third CT rates, but the example ships are a third to a half the CT rates as well, and per capita income's also down around a third to a half, so that part of it all seems to be averaging out.)

So I figured I'd go to Book 7 (Merchant Prince) and try to apply their trade system to the task. Their system's abstracted enough where you can figure out the average profit level on a trade between two planets. Sat there calculating that, ended up with a figure that ranged between about 0 and 10 (thousand credits per ton), then tried to apply it to population to figure volume - and realized I'd been wasting my time. The range of populations meant that the population code, not any specifics about tech level or trade code, was the major factor. Everything was falling in around 1 to 10 times the pop code.

So I sez to myself, "Self, ..."

('cause I'm strange that way)

"...what is it you really want to know?"

Well, what I want to know is how many ships are flying in and out of this or that starport, and how big they need to be. So I figure I can take the base population of the Marches, which I calculate at about 447.6 billion, throw out some reasonable figure for tonnage per person - which within certain broad limits can be pretty well whatever sounds reasonable - then have a good estimate about trade volume for the 447.6 billion people of the Marches. Then I can use that to figure rough trade volume for the individual worlds, applying some reasonable modifier for starport type.

I'm getting per capita tonnage figures of around 2 tons per person for the modern world and 4 to 5 tons per person for urbanized areas. I'm thinking of going with the latter, given that the bulk of the March population is in high-pop worlds. That means that Mora, for example, is shipping about 20-50 billion tons annually, while Regina ships 1.4 to 3.5 billion and little Ruby ships 40-100,000 tons. That is of course metric tons. The typical shipping container's roughly 2.5 by 2.5 by 6 meters and holds 30 tons, so I'm figuring roughly 10 metric tons per dTon ('cause it's a nice, easy round number, easier than 10.8). Means Mora needs 2-5 billion dTons of cargo space annually, about fifty to a hundred million a week, while Regina needs 3 to 7 million and Ruby needs 80-200 dTons a week. That's about 4-10 times what GURPS suggested for Mora, about 13-30 times what GURPS suggests for Regina, but about 1/50th to 1/120th what GURPS suggests for Ruby. Much wider range, which I think is what I would expect given the range of possible populations.

I can maybe argue increasing Ruby because it's basically a mining colony earning its keep through export, perhaps figuring trade at about Cr 5000 a ton and then dividing that into her GWP, which has me at best multiplying that 200dTon figure by 4 or 5, but the figure's putting me in the right ballpark, I think.

So, I'm thinking either going the tonnage route above, or sticking with GURPS for most things and going tonnage for the worlds of pop code 5 or less. Thoughts?

 

[rancke]

Anyway, I'm playing around with figuring out trade volumes for the Marches. There's GURPS, but I'm not completely satisfied with that. Works for the most part but breaks down with extremes

That was addressed. Does it still break down even with the adjustment? Also, does it break down in the upper extreme? Because breaking down in the lower extreme won't affect the overall trade volume and is best ignored or handled by hand.

...and some of the GURPS underlying assumptions are different from CT: for example, their ships can charge per parsec, which gives them a big advantage in calculating multi-parsec trade.

Assuming for purposes of argument that there are regulations that require shipping companies to charge per jump instead of per parsec[*], the result will simply be that the companies that sticks to cargo (i.e. don't charge anyone less than the cost of ferrying anything but buys, transports, and sells themselves) will outcompete the ones that carries freight and the end result is the same, since all ships pays whatever the true cost is, i.e. per parsec.

[*] Which there is at least one canonical example that shows is not, in fact, the case.​

And I'm not entirely convinced by that gravity model: sure, that 200-pop mining colony's GWP's going to be almost entirely trade, but even a small colony on a relatively earthlike world's going to be meeting a fair portion of its own needs from local resources, so the idea that they're importing everything from their big neighbor's a bit odd to me.

You're not the only one who doubts the gravity model, but I think it's better than having no model at all.

Well, what I want to know is how many ships are flying in and out of this or that starport, and how big they need to be. So I figure I can take the base population of the Marches, which I calculate at about 447.6 billion, throw out some reasonable figure for tonnage per person - which within certain broad limits can be pretty well whatever sounds reasonable - then have a good estimate about trade volume for the 447.6 billion people of the Marches. Then I can use that to figure rough trade volume for the individual worlds, applying some reasonable modifier for starport type.

You're ignoring one important factor: Trade between two worlds two jumps apart require twice the shipping tonnage for the same volume of trade as trade between two worlds one jump apart.

I'm getting per capita tonnage figures of around 2 tons per person for the modern world and 4 to 5 tons per person for urbanized areas. I'm thinking of going with the latter, given that the bulk of the March population is in high-pop worlds.

But modern world figures can't tell us what percentage of trade is with other systems. Most of the trade you calculate would be domestic trade and wouldn't contribute to the number of ships in the starport.

That's about 4-10 times what GURPS suggested for Mora, about 13-30 times what GURPS suggests for Regina, but about 1/50th to 1/120th what GURPS suggests for Ruby. Much wider range, which I think is what I would expect given the range of possible populations.

Have you really calculated all of Mora's and Regina's trade? I've been working with figuring out Regina's trade with just the other worlds in the duchy, and that alone is a daunting task.

I can maybe argue increasing Ruby because it's basically a mining colony earning its keep through export, perhaps figuring trade at about Cr 5000 a ton and then dividing that into her GWP, which has me at best multiplying that 200dTon figure by 4 or 5, but the figure's putting me in the right ballpark, I think.

Out of curiosity, how much trade does FT suggest for Ruby and how did you calculate that figure?


Hans

 

[HG_B]

Works for the most part but breaks down with extremes and some of the GURPS underlying assumptions are different from CT: for example, their ships can charge per parsec,

Scratch CT. If the Imperium forbade charging by parsec there would be almost no trade. Just toss the insanity and move forward.

 

[Timerover51]

Well, what I want to know is how many ships are flying in and out of this or that starport, and how big they need to be. So I figure I can take the base population of the Marches, which I calculate at about 447.6 billion, throw out some reasonable figure for tonnage per person - which within certain broad limits can be pretty well whatever sounds reasonable - then have a good estimate about trade volume for the 447.6 billion people of the Marches. Then I can use that to figure rough trade volume for the individual worlds, applying some reasonable modifier for starport type.

I'm getting per capita tonnage figures of around 2 tons per person for the modern world and 4 to 5 tons per person for urbanized areas. I'm thinking of going with the latter, given that the bulk of the March population is in high-pop worlds. That means that Mora, for example, is shipping about 20-50 billion tons annually, while Regina ships 1.4 to 3.5 billion and little Ruby ships 40-100,000 tons. That is of course metric tons. The typical shipping container's roughly 2.5 by 2.5 by 6 meters and holds 30 tons, so I'm figuring roughly 10 metric tons per dTon ('cause it's a nice, easy round number, easier than 10.8). Means Mora needs 2-5 billion dTons of cargo space annually, about fifty to a hundred million a week, while Regina needs 3 to 7 million and Ruby needs 80-200 dTons a week. That's about 4-10 times what GURPS suggested for Mora, about 13-30 times what GURPS suggests for Regina, but about 1/50th to 1/120th what GURPS suggests for Ruby. Much wider range, which I think is what I would expect given the range of possible populations.

I can maybe argue increasing Ruby because it's basically a mining colony earning its keep through export, perhaps figuring trade at about Cr 5000 a ton and then dividing that into her GWP, which has me at best multiplying that 200dTon figure by 4 or 5, but the figure's putting me in the right ballpark, I think.

So, I'm thinking either going the tonnage route above, or sticking with GURPS for most things and going tonnage for the worlds of pop code 5 or less. Thoughts?

Ten metric tons mass per displacement ton is about twice as high as it should be, given real world shipping standard. Five metric tons mass per displacement ton is what I am using.

How many millions of shipping containers are you expecting your port to handle per week? That passes the ridiculous and borders on fantasy.

Exactly what are all this imports and exports supposed to consist of? Not some abstract number on paper dreamed up by someone who has not the foggiest idea of real world trade, as it appears GURPS does not, and I already knew that Merchant Prince did not.

 

[Carlobrand]

That was addressed. Does it still break down even with the adjustment? Also, does it break down in the upper extreme? Because breaking down in the lower extreme won't affect the overall trade volume and is best ignored or handled by hand.

I recall that but don't remember the detail. I finally got my hands on a GURPS Free Trader, and there's a bit in there that says BTN can't exceed the smaller WTN plus 5. Not sure if that's in place on those trade maps, I'll check. Is that what you're talking about?

Assuming for purposes of argument that there are regulations that require shipping companies to charge per jump instead of per parsec[*], the result will simply be that the companies that sticks to cargo (i.e. don't charge anyone less than the cost of ferrying anything but buys, transports, and sells themselves) will outcompete the ones that carries freight and the end result is the same, since all ships pays whatever the true cost is, i.e. per parsec.

[*] Which there is at least one canonical example that shows is not, in fact, the case.​

Yuppers, and as HG notes,

Scratch CT. If the Imperium forbade charging by parsec there would be almost no trade. Just toss the insanity and move forward.

which also makes it a bit easier to use the GURPS model, since they then both work from the same base assumption. So, that's one tiny bit of canon that I'm inclined, with regret, to ignore.

You're not the only one who doubts the gravity model, but I think it's better than having no model at all.

Too true. I am, sadly, quite weak on economic theory. Also on high energy physics, but that's neither here nor there.

You're ignoring one important factor: Trade between two worlds two jumps apart require twice the shipping tonnage for the same volume of trade as trade between two worlds one jump apart.

In fairness, I can't be said to be ignoring a factor that I'm ignorant of, and I'm not averse to admitting when I'm ignorant. I'm not sure I understand what you're saying. A jump-2 ship loses volume to increased fuel tonnage and drive space, but I didn't think it was a twice thing. A jump-1 ship running the same route takes twice as long, with the result that it takes twice as many ships to run the same weekly cargo volume - is that what you're referring to?

But modern world figures can't tell us what percentage of trade is with other systems. Most of the trade you calculate would be domestic trade and wouldn't contribute to the number of ships in the starport.

Agreed. ALL of modern trade is "domestic" in terms of being confined to the planet. Gods alone know how much of that would go outsystem if we could get it off-planet without spending a fortune and had a trade partner a week away in Proxima. Perhaps that 2 to 5 bit is overly optimistic.

Have you really calculated all of Mora's and Regina's trade? I've been working with figuring out Regina's trade with just the other worlds in the duchy, and that alone is a daunting task.

Really? Not by a longshot. Just with the biggest nearby prospects. I figure that gets me in the ballpark.

Out of curiosity, how much trade does FT suggest for Ruby and how did you calculate that figure?

Ruby: B400445-B, nonindustrial, vacuum world. From that Spinward Marches sector trade map in TravellerRPG, it runs a feeder route to Jewell and minor routes to Mongo, Emerald and Chwistyoch. Average 13000 dTons cargo per week.

Now let's test that.
Ruby: Pop code/2 + TL mod, UWTN = 3. Starport B, so WTN = 3.5.

Ooh, that's already interesting, 'cause the trade map claims a WTN of 7.

Jewell: A777999-C, UWTN = 5.5, WTN = 5.5.

Trade map says they're a B. I wonder why it's doubled. My book's 3rd edition, wonder if that's it.

Anyway, BTN = WTN1 + WTN 2 + a mod for trade classifications - a distance mod, 3.5+5.5+0.5 for a nonindustrial world trading with an industrial world - 0 for range = 9.5, which translates to 10 - 50,000 dTons weekly on the table, which is kind of a lot for 20,000 hardworking souls. The other worlds aren't the elephant Jewell is, so I won't bother with them for the moment, though I'm trying to come up with an Excel spreadsheet that can handle it.

Ten metric tons mass per displacement ton is about twice as high as it should be, given real world shipping standard. Five metric tons mass per displacement ton is what I am using.

The typical modern 2.5 by 2.5 by 6 is coming in ad 30 metric tons loaded. That's awkward for Traveller, since we're using the base 1.5 meter block, but it comes to 30 metric tons for 37.5 cubic meters. That's pretty close to 10 metric tons per dTon, and it makes my math a lot easier - all I need to do is move a decimal place. My own TU uses 3-by-3-by-6'ers, actually a little bit less for overhead room and such, but 40 tons mass for 4 dTons volume.

How many millions of shipping containers are you expecting your port to handle per week? That passes the ridiculous and borders on fantasy.

Well, it is a planet, after all. Lots of space up there in orbit. On a world like Mora, my customs and offloading occurs in orbit, and then the shipments go directly to the destination cities - and in some cases directly to the companies' planetside loading docks - by GTO grav truck. Theres more than one orbital port, and they're each the size of a small city. The downports - again more than one - handle customs for outbound traffic before it goes to orbit.

Exactly what are all this imports and exports supposed to consist of? Not some abstract number on paper dreamed up by someone who has not the foggiest idea of real world trade, as it appears GURPS does not, and I already knew that Merchant Prince did not.

Computers? Rubber duckies? Silk Kimonos? We trade anything and everything nowadays, don't see why they wouldn't do the same in the future. A thousand credits shipping for ten metric tons of plastic pellets could make it cheaper to import plastic pellets for plastics production rather than produce plastic locally on a world with meager petroleum deposits.

As Rancke points out, there's no real framework for extrapolating. I think my use of modern international trade values was a mistake, so it's probably no surprise that my guesses for Mora and Regina were much higher than GURPS might have said - which is why I do a post like this: I need to test my basic assumptions. At any rate, we're pretty free to set whatever parameters suit our preferred view of the milieu, whether it's GURPS' view of hundred-thousand ton megafreighters or a small-ship universe in which most worlds are pretty independent and only a tiny fraction of trade makes it into orbit.

Me, I like megafreighters, they lend a certain grandeur - but I can't see places like Ruby pulling off the volume that GURPS suggests, so I'm trying to work out an alternative for those smaller worlds.

 

[Timerover51]

I think that I have said as much as I safely can. Any more is going to get me into trouble.

 

[rancke]

I recall that but don't remember the detail. I finally got my hands on a GURPS Free Trader, and there's a bit in there that says BTN can't exceed the smaller WTN plus 5. Not sure if that's in place on those trade maps, I'll check. Is that what you're talking about?

Yes.

In fairness, I can't be said to be ignoring a factor that I'm ignorant of, and I'm not averse to admitting when I'm ignorant.

Overlooking then.

I'm not sure I understand what you're saying. A jump-2 ship loses volume to increased fuel tonnage and drive space, but I didn't think it was a twice thing. A jump-1 ship running the same route takes twice as long, with the result that it takes twice as many ships to run the same weekly cargo volume - is that what you're referring to?

No, I'm assuming the most efficient jumps (which is jump-1 for one parsec and a combination of jump-2 and jump-3 for most other distances, although astrography can make jump-4 more efficient in certain places). What I'm talking about is multiple jumps. For example, if you need X jump-3 ships to ship a given tonnage from Regina to Roup, you'll need 2X ships to ship the same tonnage the six parsecs from Regina to Efate. Shipping from Regina to Jewell takes 2X jump-3 ships from Regina to Efate, some jump-1 ships to get from Efate to Louzy, X more jump-3 ships from Louzy to Nakege, and some jump-2 ships from Nakege to Jewell[*].

[*] I'm not sure, but I think the 4-parsec route from Efate to Lysen may be an example of the cases where jump-4 ships are cheaper.​

Ruby: B400445-B, nonindustrial, vacuum world. From that Spinward Marches sector trade map in TravellerRPG, it runs a feeder route to Jewell and minor routes to Mongo, Emerald and Chwistyoch. Average 13000 dTons cargo per week.

Now let's test that.
Ruby: Pop code/2 + TL mod, UWTN = 3. Starport B, so WTN = 3.5.

Ooh, that's already interesting, 'cause the trade map claims a WTN of 7.

Jewell: A777999-C, UWTN = 5.5, WTN = 5.5.

Trade map says they're a B. I wonder why it's doubled. My book's 3rd edition, wonder if that's it.

Anyway, BTN = WTN1 + WTN 2 + a mod for trade classifications - a distance mod, 3.5+5.5+0.5 for a nonindustrial world trading with an industrial world - 0 for range = 9.5, which translates to 10 - 50,000 dTons weekly on the table, which is kind of a lot for 20,000 hardworking souls.

It caps at 8.5 -- 5 more than the smallest of the two WTN. Between 50,000 and 100,000 dT per year. However, that's still seems too much. The credit value is supposedly 500-1000 MCr per year, or at least 25,000 credits per man -- on a world with a per capita income of 2342!

Perhaps a cap of twice the lowest WTN would be better?


Hans

 

[aramis]

(Prefix? What the heck's a prefix?)

Prefixes show up in the thread listings in alternate color. They are optional in most areas of the board. (Certain areas open to Moot members have mandatory prefixes.)

On the other hand, if someone is talking "OTU only" and someone decides to start off with "IMTU..." they will get a warning.

 

[Carlobrand]

...Overlooking then.

That works. Or missed, or forgot, or neglected, as for example this next part, where I just got through talking about that "5 more" bit and then completely forgot to apply it.

...
It caps at 8.5 -- 5 more than the smallest of the two WTN. Between 50,000 and 100,000 dT per year. ...

...

Perhaps a cap of twice the lowest WTN would be better?

I'm thinking 4 more works better than 5 more, but I'll have to play with it a bit to be sure.

 

[mike wightman]

Actually I think timerover is right on the button.

You have to start with one world.

Decide what the exports and imports are likely for a given world's trade classification using the trade goods table in CT, and then look at which adjacent planets can supply the needed imports or provide markets for the likely exports.

Next use relative population numbers, presence of bases and starport type to decide on the volume of trade required, this is the step that may take a common sense. Not much point shipping 6 ATVs to a population 1 world, unless they are all millionaires and want one in each colour.

Then move onto the next world.

It's going to take a very long time to detail a subsector like this...

 

[HG_B]

Actually I think timerover is right on the button.

You have to start with one world.

Decide what the exports and imports are likely for a given world's trade classification using

Nope. Macro econ doesn't work out that way. That would only be true if those 2 planets JUST discovered each other...

 

[Dragoner]

Then once the calcs for the sector are done, don't forget to refigure them quarterly for about a thousand years; then you will need forecasts as well. It should be done for the entire Imperium, only about 44,000 iterations and then the adjustments and recalc's, it probably won't take more than 10 years. :devil:

 

[HG_B]

Then once the calcs for the sector are done, don't forget to refigure them quarterly

Umm, no. Restudy your Econ books.

 

[Dragoner]

Umm, no. Restudy your Econ books.

I was being nice, but go ahead, do it by the minute for a thousand years if you want to.

 

[HG_B]

I was being nice, but go ahead, do it by the minute for a thousand years if you want to.

 

[Dragoner]

Hint: Business really cares about the quarter because of a word with a big T and little x, and I ain't talkin' Texas! :rofl:

 

[Carlobrand]

Prefixes show up in the thread listings in alternate color. They are optional in most areas of the board. (Certain areas open to Moot members have mandatory prefixes.)

On the other hand, if someone is talking "OTU only" and someone decides to start off with "IMTU..." they will get a warning.

Thank you. Nice to see improvements, but occasionally they catch me off-guard.

Actually I think timerover is right on the button.

You have to start with one world.

Decide what the exports and imports are likely for a given world's trade classification using the trade goods table in CT, and then look at which adjacent planets can supply the needed imports or provide markets for the likely exports.

Next use relative population numbers, presence of bases and starport type to decide on the volume of trade required, this is the step that may take a common sense. Not much point shipping 6 ATVs to a population 1 world, unless they are all millionaires and want one in each colour.

Then move onto the next world.

It's going to take a very long time to detail a subsector like this...

That's what technology is for. I'm trying to see if I can make Excel dance to this tune.

Then once the calcs for the sector are done, don't forget to refigure them quarterly for about a thousand years; then you will need forecasts as well. It should be done for the entire Imperium, only about 44,000 iterations and then the adjustments and recalc's, it probably won't take more than 10 years. :devil:

Actually, I think subsector will work just fine, so long as I include three or so parsecs of each neighboring subsector. Not perfect, but close enough for game purposes. I really don't need to know what percentage of Mora's trade finds its way to Jewell.

Hint: Business really cares about the quarter because of a word with a big T and little x, and I ain't talkin' Texas! :rofl:

Toxicology?

Seriously though, the hard part of business taxes isn't the demographic projections - it's the business of figuring out what the myriad laws actually require and finding a way to minimize your exposure without breaking one of those laws. What businesses REALLY want the model for is to plan business decisions around it: how many widgets can we expect to sell at Efate, and is our current production capacity adequate or should we plan to hire more workers and expand?