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Origin-Based Trade for Mongoose Traveller

This article originally appeared in the September/October 2018 issue.

Introduction: The Two Trade Systems

The trade system in Classic Traveller Books 1-3, based on pricing specific trade goods (’Goods-Based Trade’, ‘GBT’ henceforth), had some advantages over the trade system introduced in Classic Traveller Book 7: Merchant Prince (which was based on characteristics of the origin world, henceforth ‘OBT’, for ‘Origin-Based Trade’) and carried into later versions of Traveller. Of the 36 possible Trade Goods specified, most were worth more than the trade goods available in OBT. On a ton for ton basis, fifteen were worth kCr100 or more and four of those four were worth MCr1 or more! Even someone in a Type S could make bank on those. On average the value of speculative goods were over eight times as great in GBT as in OBT.

In most respects I prefer OBT. I was instrumental in convincing Marc that if you are buying from a primary producer you can probably buy as much as you want to buy, which is why there were no quantity rolls in OBT; however, I missed some aspects of GBT. Trading in Traveller today has become a work-a-day job performed in a perfunctory fashion. You know before you arrive what you can get and how much you’ll pay for it. There is never a trading reason you’d need to stay in a starport beyond the six days allowed for your initial landing/docking fee.

The Mongoose system is basically an expansion of GBT. However, like the original GBT, not everything is covered. Can you imagine how many tables would be needed to cover all the possibilities? Even in generic groups the minutia would be staggering.

That’s one of the reason OBT was created. Using it, we don’t need to detail every possible trade good or even every trade category, and if new products are added, we don’t need new tables. However, it has no luck involved on the buying end and getting ahead in life requires a few lucky breaks.

The Origin-Based Trade System

For those who only have Mongoose, the OBT system is reproduced here (modified very slightly for Mongoose). The High Tech and Low Tech codes are omitted from these tables, as Tech Level is accounted for directly.

The factors that affect the price of goods, both for purchase and for sale, are the starport class, the tech level of the world, and the world’s trade codes. Any of these may influence the cost in either direction.

For our example worlds, we will use two TravellerMap worlds, Miidkhim (Fornast 0217, C899487-A Ni) and Kaskii (Core 3218, A300A98-F Hi In Na Va Cp). Note that, as presented, Kaskii’s status as a subsector capital (Cp) has not effect on trade.

Step 1: Determine the Cost of Goods

Starport and Trade Class Cost Modifiers
A -1 Ag -1 Hi -1 Ni 1
B 0 As -1 Ic 0 Po -1
C 1 De 1 In -1 Ri 1
D 2 Fl 1 Lo 1 Va 1
E 3 Ga -1 Na 0 Wa 0
X 5            

Goods are priced by the ton. Calculate the total cost modifier for goods purchased on the world by summing the values given for each of the world’s trade codes on the Starport and Trade Class Cost Modifiers table (this result is allowed to be negative). Add 4 to the result, and multiply by 1,000. This represents the trade-code cost of goods. It must be modified by the world’s tech level. Multiply the tech level by 100, and add the two results. This gives the final cost of goods.

For our example worlds, the purchase cost modifiers on Kaskii will be starport A (-1), Hi (-1), In (-1), Na (0), and Va (1) for a total of –2. Add 4 to this (= +2), and we find a base trade-code cost of Cr2,000 per ton. The tech level on Kaskii is F (15), so we add 15×100, or 1,500, to the base trade-code cost, and get a final purchase price of Cr3,500 per ton. Note this as A-F Hi In Na Va 3500, where A is the starport code, F is the tech level, Hi In Na Va are trade codes of the source planet, and 3500 is the cost per ton in credits.

For Miidkhim, the modifiers are starport C (1), Ni (1), for a total of 2, +4 for a trade-code cost of Cr6,000, and a TL of A (10) adds another Cr1,000 for a final cost of Cr7,000. Note this as C-A Ni 7000.

This step may be done in advance, if you are preparing a Commercial Atlas.

Step 2: Determine the Base Sale Price

Sale Price Modifiers
  Market Code
Ag As De Fl Ga Hi In Lo Na Ni Po Ri Va Wa
Ag +1 +1 +1 +1 +1 +1 +1 +1 +1
As +1 +1 +1 +1 +1
Ba +1 +1 +1
De +1 +1
Fl +1 +1
Ga +1 +1 +1 +1 +1 +1 +1 +1 +1
Hi +1 +1 +1
Ic +1
In +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
Lo +1 +1
Na +1 +1 +1
Ni +1 −1
Po −1
Ri +1 +1 +1 +1 +1 +1 +1
Va +1 +1 +1
Wa +1 +1 +1

Sale prices are also set by the ton. Calculate the price modifier for the goods by summing up the modifiers for each combination of trade codes from source and market world on the Sale Price Modifiers table. For each trade code from the source world, find the modifier under each trade code for the destination world. Values of “—” are treated as 0. This sum is also permitted to be negative. Add 5 to the result. This is the trade-code price factor. As a separate calculation, subtract the tech level of the market world from that of the source world. This result is also allowed to be negative. Multiply this number by the trade code price factor. This result is the tech factor. To determine the base selling price of the cargo, multiply the trade-code price factor by 1,000, and the tech factor by 100, and add the two results.

For our example worlds, if we are selling goods from Kaskii on Miidkhim, we look for the values at the intersections of Kaskii’s trade codes of Hi, In, Na, and Va (in the leftmost column of the table) with Miidkhim’s trade code of Ni (in the top row of the table). That gives us Hi/Ni (0), In/Ni (+1), Na/Ni (0), and Va/Ni (0), for a total of +1, to which we add 5, for a trade-code price factor of 6. For the tech factor, we subtract Miidkhim’s tech level of A (10) from Kaskii’s F (15), giving 5, which we multiply by the trade-code factor of 6, giving a tech factor of 30. Our base selling price is given as 6×1000, plus 30×100, or Cr9,000 per ton. This is not necessarily the price you will actually sell for; it is the starting point for determining the actual price.

If we are selling goods from Miidkhim on Kaskii, the process is similar, but we look for Miidkhim’s trade code of Ni in the leftmost column on the table, and take the values from Kaskii’s trade codes of Hi (0), In (+1), Na (0), and Va(0), for a total of 1, plus 5 is a trade-code factor of 6. The tech factor is A (10) - F (15), yielding –5, multiplied by 6, for a tech factor of –30. The base selling price is 6×1000 + (-30)×100, or Cr6,000 - Cr3,000 or Cr3,000.

This step may also be done in advance, if you are preparing a Commercial Atlas.

Step 3: Determine the Final Sale Price

Final Sale Price
2D Price Multiplier 2D Price Multiplier
2 40% 9 120%
3 50% 10 130%
4 70% 11 150%
5 80% 12 170%
6 90% 13 200%
7 100% 14 300%
8 110% 15 400%

Once you have determined the base selling price, roll on the Final Sale Price table to determine what kind of a deal you can actually make to sell your goods. You may hire a broker to assist; the broker’s skill gives you a DM +1 for each level, but you must pay him 5% of the final purchase price for each skill level as a fee. This fee also applies if you act as your own broker; the fee goes into your personal wealth, not the trading accounts. You may also resort to bribery; each two levels of bribery skill gives you a DM +1. The people you bribe receive a kickback of a flat 7% of the final sale price, regardless of DM.

This step can only be done at the time of sale.

Variant Rules

Refusing Sales

You may decide that a trader is not required to sell at an unsatisfactory offering price. Under this variant, the trader may wait a week and try again, incurring a cumulative DM of -1 per prior attempt (that is, the second attempt is at -1, the third is at -3, the fourth at -6, and so on).

Value Multiples

Just by reading though the available equipment and supplies lists it is obvious that most things you could buy as speculative trade items will not be worth the prices calculated using OBT. Some would be worth less and others worth more, sometimes much more. Some things would be worth over GCr1/ton. Of course those would be extremely rare.

With GBT it was possible to make payments on a Free Trader on speculative trade and carrying paid passengers and freight was just a sideline to your main business of trading in speculative goods.

So, how do we modify OBT to allow it as well? Simple, introduce a price multiple and/or change the wording from price per ton to price per unit and have variable unit sizes. For example, the unit size for most pharmaceuticals would not normally be a ton (not that you couldn’t buy pharmaceuticals by the ton, but that they would be worth a whole lot more than a few kCr per ton).

In GBT there were cargos that weren’t worth your time to carry so you might actually wait in port a week to see what else might be available. This OBT system, as written, doesn’t allow for that; adding a random factor on purchase could do so.

I finally decided to leave the wording the same and introduce a value multiple. When PCs land/dock the brokers and other representatives of local business concerns will be there waiting. The PCs post to the desired cargo boards and will be approached by various representatives to sell what they have. They can always accept a standard offer or leave the port and look for something better.

Search Time
2D Days
5– 3
6,7 4
8,9 5
10+ 6

Arranging for a standard purchase will take a day or less, but searching for something better will take 3–6 days and cost the same as a ton of standard cargo. Roll on the Search Time table to find the time. DM: -1/level of broker.

Value Multiplier Table
3D* Value Multiple DM
12– 1 NA
13-18 d9 +1
19-24 d9×10 +2
25-28 d9×100 +3
29,30 d9×1,000 +4
31-33 d9×10,000 +5
34-42 d9×100,000 +6
43+ 1,000,000 +8

At the end of the search, roll 3D* on the Value Multiplier table with a DM of +1/level of broker and -1/previous search period. The * in 3D* means “open ended”, sometimes called “exploding sixes”. To make an “open ended” roll, take the sum from the initial roll, reroll any 6s, and add the new rolls to the total. If any of the rerolled dice come up 6, reroll them as well (after adding them to the total). Continue adding and rerolling 6s until no 6s are rolled or you reach whatever level you want (probably 43+). If the final roll is 12– no better cargo is available. One can always take a regular cargo and move on, or search for another week and try again. The cost for each extra week is the same as the first try.

D66 to D9 Conversion
D66 D9
11-14 1
15-22 2
23-26 3
31-34 4
35-42 5
43-46 6
51-54 7
55-62 8
63-66 9

Assuming that you’ve found a better cargo (that is, your 3D* roll was 13+), you now must determine the value multiple. This is written as ‘d9 × «power-of-10»’, and is read from the same row as your 3D* roll. The d9 indicates a range of 1 to 9, in a linear distribution (that is, equal probability of any result). Since there is no such thing as a nine-sided die, you’ll need to improvise. The two simplest ways are (1) roll a d10, rerolling any 0s or 10s (whichever your die is marked with), or (2) roll D66 on the D66-to-D9 Conversion table to find the needed multiple.

Now that you know what the value multiple is you need to find the minimum purchase (or lot size) in tons to make the deal. If the value multiple is 1 then the lot size is 1 ton; otherwise, roll 2D on the Lot Size table (DM +1 per level of broker skill, plus the value from the DM column on the row of your 3D* roll on the Value Multiplier table), then roll D9 as above, to determine the lot size. The amount you buy must be a whole number (no fractions or decimals) multiple of the lot size, but need not be a whole number of tons.

Lot Size
2D Minimum
4– d9
5-8 d9/10
9-12 d9/100
13-17 d9/1,000
18+ d9/10,000

If we decide to search for a better deal than standard on Kaskii (A-F Hi In Na Va 3500) and find it during the first week, we would pay Cr3500 for the search, and then start rolling dice. Our 3D* roll is 23, which gives us a Value Multiplier of d9×10, and a DM of +2. We now roll a D9 for 4, meaning our value multiplier is 40. Our per-ton cost for this cargo is Cr3500×40, or Cr140,000 per ton. We note this cargo as C-A Ni 3500×40. We roll 2D+2 on the Lot Size table for 8 (lot size D9/10 tons), and another D9 for 5, meaning that we can buy lots of 5/10 tons, at Cr70,000 per lot.

When we get it to Miidkhim (C-A Ni 7000), the value multiplier and lot size still apply, but to Miidkhim’s base price as determined earlier (Cr9,000), or Cr9,000×40 or Cr360,000 per ton (or Cr180,000 per lot). Even a lousy roll would provide a nice profit. Of course not all markets are as advantageous as this, and good traders watch these things.

If you allow this variant, you should also probably allow players to keep track of good buys they’ve found and to check back with those suppliers to see if they have more of the same. The better the find, the less likely they’ll have a surplus at any given time. However, contacts are part of what the trading game is all about.

On the Value Multiple table a roll of 43+ is a once in a century deal, the ultimate strike. 34+ is a once a decade deal. You’ll get 31+ every five years or so. 29+ is about every other year. 25+ you should find annually. 19+ comes around every quarter. 13+ with a 2+ on the d9 will show up every other cargo or so.

If you hit a 43+, let’s hope you have enough capital or good relations with your banker!