Celebrim
Legend
I believe your typical 100 ton square-rigged 2nd Century Roman merchant ship has a crew of around 5 hands
I'd love to see your sources, because in 5000 pages of reading on age of sail ships, I never could find numbers for the crew of Hellenistic sailing ships and had to ball park them based on typical great age of sail numbers.
I'll just say that there is a big difference between the crew you need to sail 4 hours across a bay or strait, and the crew you need to keep a boat operating 24 hours a day for days at a time. I'm not at all convinced that the simplicity of the rigging on a Cog or Hulk made them require less crew than a later sloop or schooner. For one thing, changing the sail often meant taking the yard arm down, setting the sail, and then hauling the arm back up again. This is not an undertaking for small number of crew.
Truthfully our modern notions of trade and economics are very foreign to pre-modern times. A REALISTIC medieval town of say 1100 AD wouldn't even have shops where you could spend coin at all. Virtually all production was handled by people bound up in various types of labor and trade obligations and there simply was no such thing as retail sales. The best you would do would be itinerant traders who distributed the few outside goods consumed by rural settlements. In a village the notion of purchasing some sort of good would have been ridiculous, everything made there or brought there was accounted for and needed by someone.
I pretty much disagree with all of that in detail. First, as I noted, the PC's are aboard a ship rigged Corvette, so even the assumption that the economics mimic high medieval economics is one that probably should be put on hold.
But in relation to your view of trade in the middle ages, I'll just put what my own medieval history professor wrote in red ink on one of papers, "Perhaps we should read more widely than just Charles Oman."
While medieval economics were largely local, and largely manorial, and largely based on simple barter, to claim that in 1100AD even a medieval town doesn't have shops is simply boggling. I'm not sure that I'd go so far as to suggests the towns of Northern Europe in the 8th century were so primitive, though the very lack of sources might make it impossible to answer the question definitively. At the very least, the defining aspect of a town by 1100AD was that they had a right to hold a Fair, where one could find a market, and goods were freely traded both by townsfolk and people from the surrounding area. In addition to shops, this would have meant any number of impromptu stalls and carts filled with local homemade goods. A typical town would also have at the least a cobbler (or two, probably the most common non-agrarian profession), a miller, a blacksmith, and probably a brewer (and with it a public house). Larger towns would probably have had at the least tailor, butcher, tanner, barber and baker as well with a whole host of other industries based on the locality - glass blowers, potters, brick makers, fullers, chandlers, felters, haberdashers, joiners, turners, whitesmiths, brownsmiths, jewelers, dyers, painters, furriers, stave cutters, thatchers, coopers, cartwrights, and the almost innumerable host of highly specialized medieval trades that made up the cogs in medieval industry. Many or most goods would have been made on commission - the cobbler probably wouldn't have had rows of shoes in your size waiting to be bought - because that required to much invested capital, but there would likely have been at least some finished goods available. Yes, these craftsman's shops would have doubled as their homes, but they were still places of business where you could buy things.
Even the smallest medieval village was supporting remote trade in some form. Granted, it might just be wheat that would end up in the town 16 miles away after passing through the apparatus of feudal government, to become the Lord's tax, then the Baron's tax, and then sold to merchant in town for coin so that the Baron could buy goods like mail and horses from other merchants. But a close observation of the medieval economy shows it was highly international. What it wasn't was centralized, but that doesn't mean that it was actually localized. Medieval villages were largely self-sufficient, but no one village could manufacture everything it needed. Even serfs needed and could buy cooper and iron tools forged in remote locations (and thus, local smiths to repair these valuable goods). People bought and sold and always have. Trade on an transcendental scale existed even in stone age America, with Michigan copper turning up in Colorado and Colorado obsidian turning up in Michigan. And Europe's trade networks were far more advanced than that during the same period. Remember, in 1100, population and trade in Northern Europe had reached the point that Northern Europe was able to organize and mount a successful invasion of the ancient heartland of human civilization - and it did so ostensibly because it was frustrated by the barriers to trade and traffic that recent regimes in the Middle East had raised.
Let's put it this way: trade in Europe in the middle ages was so highly developed, that in the course of a single year, pilgrims to one particularly famous Cathedral hoping to see its array of relics bought 200,000 souvenir lead pins made by local casters so that they could take them home and display their piety to their neighbors. Disneyland has nothing on that sort of commercialization. It would be wrong to see the medieval world as just being a different version of the modern world. But it would be equally wrong to see it as being utterly and radically different in every way. People are people.