Looking for feedback: ocean trading

I've been quietly plugging away at Jar of Dirt, my own selection of rules for a pirate wavecrawl. It's my favorite bits and pieces from the GLOGosphere, collected in one document for ease of use. I'll be posting it in a couple of weeks. Right now I'm looking for feedback on a subsystem for ocean trading that I wrote up myself. Gotta stock those boats!

Like it, hate it, want to tinker with it? Hit me with your thoughts in the comment section.

This, ad infinitum. (from)

QUESTIONS I NEED ANSWERED DURING PLAY

At some point, PCs with their own ship are going to capture cargo and try to sell it. So what's that ship carrying in the first place, what's it worth and where is the best place to sell it? This system should quickly answer questions as they pop up duing play. It also contains enough under-the-hood logic that I can use it to generate stories during session prep. You'll get the underlying tables first, the table-ready tables are at the bottom of the post.

Player questions:

• We've boarded a fat merchant ship, what are they carrying?
• We're in a crazy new port, what do they sell here?
• Where do we get the best price for this liberated equipment?
• Where do we buy stuff at the lowest price?

DM questions:

• Where's this ship coming from, what's it carrying and what's that worth?
• What are the big trade routes on the world map and on the regional maps?
• What's the local demand for the cargo?
• What do the locals really want and what do they have to offer?
• (How many more rounds until the Kraken attacks?)

Cross-section of a Spanish galleon, Stephen Biesty (from)

MY APPROACH: STEAL FROM THE BEST, DETAIL THE REST

Expand Skerples' ship ship system. Ships have a limited number of inventory slots for cargo, you can go over that limit in return for harsher travel events, and you can roll to see what's in a passing ship. I'll keep his ship types (adding a couple) but will rework the cargo types and values to match my restocking tweak.

How to determine cargo values? I started from Yoon-Suin's system, but wanted something both more granular (in terms of what each region offers/wants) and more general (in terms of prices per individual item). Yoon-Suin offers a nice source/demand framework. I end up assigning goods to general cargo categories, each with a fixed low and high base price. Rum and tobacco are both low value vices with the same price; opium and red honey are three times as valuable, and so on.

Keep the cargo lists as short as I can. I've resisted the completist/simulationist temptation to include nine kinds of timber or fifteen different spices, each priced differently. If this system becomes unwieldy, I'll just end up not using it at the table. Collapse those trade goods into general categories and shine a spotlight on the weird and exciting. 

Detail a supply and demand table. Every region on my world map gets a list of goods it Sources (base price), Desires (premium price) and is uninterested in (buy at low price, don't sell). All other cargo will be Traded at a price between Source and Desire. I decide against doing this for every individual port in each region. Can work out differences from the baseline during play if it comes up.

Update: to clarify, this is what a wealthy trader in the area would be willing to pay for the cargo. If no such trader exists because the party moored their ship in a tiny fishing hamlet, offer less or don't go for the deal at all. I'm not going to write down purchasing power per port (P^4); just too much hastle for something I'd much rather improv off this general system.

Alternative option: I could just have set the buying price for a cargo type in each port only depend on its base price x months of travel from the nearest source. But then I'd end up with the low-tech Isle of Dread being quite interested in books or porcelain, where I think rum and firearms make more sense. What's more, every time I want to find out the going price for an item, I'd need to pull up the world map and count travel times. Too much hassle.

Write up encounter tables for types of ships. The big supply/demand table I've got going is nice, but a pain to lay out and use quickly at the table. I decide to write up stocking tables for different kinds of ship missions. One spice trader might be hauling different things than the next, especially depending on whether they're outbound or incoming, but both will carry very different cargo than a local trader or a colony supply ship. This encounter table can quickly generate cargo types and still has enough variety to it.

Cloves. Steal a cargo hold full of this and you are 1) rich 2) hunted.

ENOUGH WAFFLING! SHOW US, MAN!

Update: Ancalagon_tb points out in the comments that it'd be good to have costs as wells as rewards for shipping. I'm leaning for a cost to outfit for a 2 month journey equal to 50 gp x (masts + cargo units). Masts run 0-3 per ship, cargo units run 1-6. Short trips can earn money off of lower value cargo; but if you're hauling merchandise from Yoon-Suin all the way to the Old World, you had better be hauling spices.


Example trade
The pirate sloop Jonas captures a cargo unit each of citrus and rice off the Spice Islands (to be published). The Spice Islands are a Source of both, so selling them here would net only (5+15) x 0.5 = 10 gp.

Sailing on to the Maelstrom Islands, the Jonas finds the locals uninterested in rice (sell for 5 gp) and willing to Trade for citrus (sell for 3x 15gp = 45 gp). They dump the rice and sail on.

In the Mehabara, citrus is actually Desired, for 10x 15 = 150 gp. The Jonas could trade it for rum (70 gp) and still earn 80 gp.



Cargo types and base prices
This is in cargo units (1-6 depending on ship type). No matter the type of cargo, a cargo unit always takes up the same amount of space/weight/hassle/careful packing/feed&care.

Update: cargo units are not any one specific mass or size - intentionally so. I’d hate to have to figure out the relative mass and space that a couple of horses, boxes of muskets or bales of spice take up! Even more so when you consider extra food or careful packing. Still, it’s odd (as Ancalagon_tb points out) that a merchant ship has only 6x the cargo capacity of a tiny row boat. Quick solution: drop the cargo hold in the row boat. That shifts up the abstract size of a cargo unit for all other ships. Lazy way out? Hell yes! Recall that I want something simple and functional, not a complete and proper trade simulator.

I know that there's people in this table of cargo. Paying passengers as well as slaves. The slave trade was a horrific chapter of our history - I'm not editing it out. I will treat the sensitively during play. Not going into explicit details but will soberly state that conditions are horrific.

Animal	farm (15 gp)	5 cattle, 100 chickens, 5 horses, 15 sheep
	exotic (45 gp)	10 feathered snakes, 5 flying monkeys, 5 sea turtles, titan lizard
Food	basic (5 gp)	grain, rice, salt
	luxury (15 gp)	citrus, mango, sugar
Goods	basic (50 gp)	tools, household items, worked cloth
	luxury (150 gp)	medicine, porcelain, specialist tools (including books)
Materials	basic (10 gp)	cotton, timber, wool
	metals (30 gp)	copper, iron, tin
People	(100 gp)	5 dignitaries, 10 travelers or marines, 30 slaves
Spices	valuable (350 gp)	cinnamon, cloves, cocoa, ginger, ginseng, nutmeg, pepper
	treasured (1000 gp)	cardamom, vanilla
Vices	simple (70 gp)	coffee, rum, tea, tobacco
	exotic (200 gp)	opium, red honey
Wealth	precious (100 gp)	jade, obsidian, pearls
	treasure (300 gp)	gemstones, gold and silver, indigo, silk
Weaponry	personal (40 gp)	50 firearms, 150 melee, gunpowder
	naval (120 gp)	cannon (18lbs)

Market demand

Offload a captured cargo of citrus in the Maelstrom islands or sail on to the Mehabara? Each region prefers different goods and sets their prices accordingly. 

Merchants will offer Trade prices for any goods except those noted under Source, Desire or uninterested. Goods may also be swapped with only the remaining value being paid in coin.

• "Buy for" gives you the price to buy a good off a local merchant.
• "Sell at" is the price you'll get after selling something here. The difference is a matter of taxes, fees for go-betweens, bribes to ignore stolen goods, a fence willing to take hot goods for a reduced price, etc. It all ends up at 1/2 x the buying price.

	buy for	sell at
Source	1x cost	½x cost
Trade	6x cost	3x cost
Desire	20x cost	10x cost
uninterested	N/A	1x cost

Ape Archipelago

Source: Animals (exotic except titan lizard), firearms, cannons

Desire: Animals (basic, titan lizard), medicine, rum, red honey, gunpowder

uninterested: specialist tools, Materials (metals), Wealth

Chult

Source: Animals (exotic except f. snakes), mango, salt, Goods (basic), copper, iron, timber, slaves, coffee, Wealth (treasure except silk), melee weapons

Desire: Animals (basic), Weaponry (except melee), grain, Goods (luxury), Vices (opium, red honey, rum, tobacco), silk

Isle of Dread

Source: feathered snakes, titan lizards, mango, slaves, copper, cocoa, vanilla, Wealth (except indigo, silk)

Desire: Goods (basic, medicine), rum, Weapons

uninterested: flying monkeys, Goods (luxury except medicine), cotton, iron, timber, tin, Vices (except rum), silk, indigo

Maelstrom Islands

Source: grain, salt, worked cloth, wool, red honey

Desire: Goods (except worked cloth, porcelain), iron, tin, slaves, rum, tobacco, Weaponry

uninterested: Animals (exotic), mango, rice, Wealth (except gold and silver,  pearls)

Mehabara

Source: sea turtles, sugar, cotton, timber, rum, tobacco

Desire: Food (basic, citrus), exc. worked cloth, porcelain, iron, wool, slaves, coffee, Weaponry

uninterested: titan lizards

Old World

Source: Animals (basic), grain, salt, Goods (except porcelain), wool, Weaponry

Desire: Animals (exotic), Food (rice, luxury, rice), porcelain, Metals, Spices, Vices, Wealth

uninterested: slaves

Spice Islands

Source: timber, slaves, cardamom, cinnamon, cloves, nutmeg, pepper, pearls

Desire: Animals (exotic), Food, basic tools, medicine, worked cloth, jade, silk, Weaponry

uninterested: titan lizard, copper, cotton

Yoon-Suin

Source: rice, salt, Goods (basic, porcelain), slaves, tin, ginger, ginseng, opium, tea, Wealth (treasure except gold and silver), Weapons (melee)

Desire: Animals (exotic), medicine, specialist tools, iron, red honey, gold and silver, indigo, Weaponry (except melee)

uninterested: grain, sugar, wool, coffee, tobacco

Cornelis Verbeeck, a Naval Encounter between Dutch and Spanish Warships (wiki)

Stocking a passing ship

Ships carry two types of cargo: roll d12 to pick the type of ship and 2d10 to determine its cargo (multiplying results x 1/2 number of cargo space), or hand-pick from the list above.

Example

A caravel with 4 cargo units of hold space could be [d12]=11: heading out on the spice run, carrying [2d10]=1&6: 2x10 marines and two cargo units of medicine. Maybe they're reinforcing an Old World colony on the way to Yoon-Suin, or maybe they're preparing to defend a rich return cargo.

d12 d10	1-2 Colony supplies	3-5 Colony production	6-7 Local trader	8 Limited route
1	Animals - farm	Animals - exotic	Animals - farm	Animals - exotic
2	Goods - basic	Animals - exotic	Food - basic	Salt, rice
3	Materials - basic	Food - exotic	Food - exotic	Tropical fruits
4	Materials - metal	Food - exotic	Goods - basic	Household items, tools
5	5 dignitaries	Materials - basic	Materials - basic	Porcelain
6	10 colonists	Materials - metal	Materials - metal	Cotton, Wool
7	30 slaves	5 dignitaries	10 travelers	Copper, iron, tin
8	30 slaves	Vices - basic	Vices - basic	30 slaves
9	Weaponry - personal	Wealth- precious	Wealth- precious	Coffee, rum, tobacco
10	Weaponry - naval	Wealth - treasure	Spices - valuable	Jade, pearls, silk

d12 d10	9 Explorer - outbound	10 Explorer - returning	11 Spice run - outbound	12 Spice run - returning
1	Animals - farm	Animals - exotic	10 marines	Porcelain
2	Food - basic	Food - exotic	5 dignitaries	Worked cloth
3	Goods - basic	Goods - basic	Tropical fruits	Citrus
4	Materials - basic	Materials - metal	Goods - basic	10 travelers
5	10 marines	nothing	Medicine	Vices - basic
6	5 scholars	nothing	Medicine	Vices - exotic
7	Rum	Vices - basic	Specialist tools	Spices - valuable
8	Rum	Wealth- precious	Specialist tools	Spices - valuable
9	150 melee weapons	Wealth - treasure	Wealth - gold, silver	Spices - valuable
10	50 firearms	Spices - valuable	Wealth - indigo	Spices - priceless