lz8: I opened the trading post when the town was no more than 5 years old (can't remember the exact year). From the beginning I have had a lot of different things for trade, starting with onions, berries, roots, venison ... and adding other things (leather, logs ...) as I've gotten excess.
The town is now 43 years old, and I still haven't seen even ONE boat with any stone, iron or coal. I've dismissed boats for not having anything I want, which happens a fair amount. At least 2 boats came that were selling cattle. Same with something else. I've dismissed them without buying (no need).
Am I missing something? When a boat comes that has something I want to purchase, will it be obvious? Do you get a message saying what you purchased?
You probably already know some of this, but I'll cover what I know in case it fills any gaps.
-I think each trading post has its own timer and merchants that come, so more trading posts means more merchants. You have more posts that have to be stocked, though.
-You can see a merchant coming down the river from the time it enters the map. The kind of merchant is only decided when it actually docks at a trading post though, so if you're willing to save scum, then you can save just before they dock and reload until you see the type you want.
-There are a number of different kinds of merchant, and each one buys and sells different kinds of goods. Some merchants just won't buy certain kinds of goods (ex. food), while another merchant buy it.
-While a merchant is present, you can ask that they bring certain goods on their next trip (which is whenever they happen to be chosen by the RNG when the boat pulls up). The next time that kind of merchant appears, they'll have some amount of whatever you requested, though they will charge you more for it. This can still be a good deal if you need only certain things and don't want them wasting space on other things (for example, you want coal but don't need coats, then requesting coal should make sure the merchant has coal and not coats even if the coal is a little more expensive than if you hadn't made a special request). Be aware that if you request a whole lot of things, the merchant might not bring them all (for example, requesting everything the General Goods merchant could bring is probably going to result in his boat not having the space to bring it all).
-The various options for placing orders and such are specific to each merchant. Placing an order for coal with the Resource Merchant doesn't mean anything for the General Good merchant.
-It is entirely possible to have a string of merchants show up bringing things you don't care about. For example, you might get several boats in a row that row Seed merchant, Livestock merchant, or Food merchant, none of which are eligible to carry coal.
If you want iron, stone, or coal, then you probably want the Resource Merchant or General Goods merchant. I don't think the Resource Merchant accepts food in trade. Firewood is actually one of the best trade goods, and in my experience a couple of well placed Forester buildings can keep you well supplied with logs to run through your Woodcutters.
