Types of merchant ships and basic sailing conditions

Ships played a crucial part in the early dissemination of the Black Death. Their construction, size, sailing rates, the sea lanes, and network of supporting seaports and local harbours were central conditions. In those times, there were no weather forecasts and lighthouses were exquisitely rare. Although many ships, such as the ones built by the Vikings, were suitable for medium-distance blue water navigation, ships sailed coastwise when possible for obvious safety reasons. In the absence of lighthouses, ships moving coastwise would anchor for the night at suitable places and wait for daylight. This greatly extended the time of voyages. It also exposed ships to pirates and military predatory action by local powers, so merchant ships usually sailed in convoys.

There were two main types of commercial ships – galleys that mainly were propelled by rowers, and sailing ships. Sailing ships were also of two main types – the commercial long-distance bulk carriers, generally called roundships (nefs), such as cogs, and smaller sailing ships or boats carrying commodities in a more local pattern of trade. In the first phase of spread of plague, Italian galleys played the main role and established primary epicentres of spread, from where commercial sailing ships and local skippers and tradesmen (unwittingly) took over the spread of plague with transportation of contaminated goods or provisions. Also fishing boats have been shown to play a part.

The crucial role of Italian long-distance trade with galleys in the early spread of the Black Death

Galleys were unique ships. They were mainly propelled not by sail and wind but by oarsmen, usually about 150 of them, and had total crews of up to 200 men. They enjoyed additional moving power from two (triangular) lateen sails, which could be used with favourable tail winds, but human strength was by far the primary method of propulsion. Galleys were slender ships built for speed and high manoeuvrability. The freeboard (the height of the railing to the surface of water) had to be low to allow the rowers to work efficiently but reduced seaworthiness in relation to blue water sailing, which was quite generally avoided.