Hi there! I am currently writing my honours thesis about Venetian history around the 12th-13th centuries and in all the sources I've read so far, stopping for winter or wintering at a port city is everywhere yet never elaborated on. Although not relevant to my topic, I keep reading about it and I am curious as to why this happened. Perhaps I am being completely ignorant and the simple answer was that it was too cold to travel, but what is the reason for the ceasing of travel across the Mediterranean? For example, during the Fourth Crusade Enrico Dandolo supposedly had planned to winter at Zara/Zadar and the city was subsequently sacked as a deal to help pay the crusader's debts.
I've added some example quotes from Donald M. Nicol's 'Byzantium and Venice: A Study in Diplomatic and Cultural Relations' - for reference the first quote has a date attached ~1218 and the second quote is supposedly discussing around the collapse of the Latin Empire in 1261.
Page 268: The sailing seasons where known as 'mude' and the term was used to describe the convoys or caravans. Sailing time from Venice to Constantinople was usually about eight weeks. Caravans set out from Venice to trade in Romania twice a year, one in spring, the other in August. The first 'muda' would come back in the autumn. The second would winter in Romania and return the following Easter or even later. Many of the ships would would load or unload wares on the mainland or island ports of the Aegean on their way to and from Constantinople. But they would try to avoid sailing in the winter months.
The text never goes into detail as to why they would stop sailing during winter which puzzles me (and this has been a reoccurring thing in all the books that I have looked at for my thesis), because on the next page it talks about how the invention of the compass and new developments of sailing techniques resulted in ships being capable of sailing the seas all year round. Is the answer to my question rather that the methods of sailing by stars or following the coastline being obstructed by bad weather conditions?
Page 267: It came at a time, however, when new developments in sailing technique were beginning to have their effect. The invention of the compass soon after the middle of the thirteenth and fourteenth century and improvements in the steering mechanism of ships revolutionised the art and scope of navigation... Navigation by compass made it possible for ships to sail in cloudy or overcast weather, without being afraid of losing sight of land. Convoys from Venice could set out in the winter months, in January or February. The earlier pattern of 'mude' leaving twice a year was changed. The second convoy could leave in the summer and come back at the beginning of winter without having to winter abroad as had formerly been the rule.
It then goes on to say:
The introduction of the stern-post rudder meant that bigger ships could be built and held on course when at sea. The invention of compass bearings led to improvements in map-making. Charts or portolans could be drawn showing the position of the main harbours and islands of the Mediterranean and Aegean Seas. The earliest were drawn on vellum in Venice and Genoa. Such portolan charts, or compass charts, were a great advance on the earlier portolani, or guides for sailors, since they gave much more accurate and reliable information on the coastlines and staging posts. These improvements, though they took many years to perfect, lowered the cost of long-distance transport and made sailing a full-time profession.
Is it simply a combination of earlier sailing techniques relying on favourable visibility conditions that would be impeded during the winter months rather than say, my initial answer of it being too cold to sail or the seas being too rough to safely sail on? Apologies if this answer is a bit obvious, I have very little knowledge on sailing and maritime history. Thank you in advance!
Is it simply a combination of earlier sailing techniques relying on favourable visibility conditions that would be impeded during the winter months rather than say, my initial answer of it being too cold to sail or the seas being too rough to safely sail on?
This is the key distinction to make, and one increasingly stressed in scholarship: the idea of human ecology. That is, "nature" (climate, weather, geography, hydrology) is not inherently deterministic of human actions and history. Rather, historians focus on the human experience of these natural phenomena, which is also shaped by changing technology, spirituality, political situations, and so forth.
In this case, the underlying climatological conditions of the winter Mediterranean are handsomely attested in sources going back well into antiquity: namely, unfavorable and capricious winds, especially for trying to travel from east to west (harder even in the summer); and storms more frequent and generally more violent than in the summer. 4th century military author Vegetius, whose De re militari would become THE military handbook bestseller of the Middle Ages, wrote:
The violence and roughness of the sea do not permit navigation all year round, but some months are very suitable, some are doubtful, and the rest are impossible for fleets by law of nature...[long astrologically-based discussion of various "sets of storms" within a winter from mid-September to mid-May)]...The minimal daylight and long nights, dense cloud cover, foggy air, and violence of the winds doubled by rain and snow not only keep fleets from the sea but also traffic from making journeys by land.
But despite crediting the "law of nature" for this absolute, star-ruled situation, Vegetius goes on to say:
...not that the activities of merchants cease, but greater caution should be shown when an army takes to the sea in warships than when the enterprising are in a hurry for their private profit.
In other words, neither merchants nor navies stop in winter--it's just rarer and harder. That is to say, people experienced not just "winter" but "winter through their ways of dealing with it/avoiding it."
The distinction between merchants and navies also points to one of the first and most important ways of "dealing with it": bigger, heavier ships. Vessels for war in the late antique and medieval world generally prioritized speed, and were very often galleys--that is to say rowed, not sailed. Rowing was insufficient power up against Mediterranean winter storms, and lighter weight ships did not fare so well in wind and waves. In the early Middle Ages, it seems, Byzantine merchant ships continued to model themselves after ships for war, staying relatively lightweight; and sure enough, Christian authors bemoan the Arabs' penchant for popping up in hostile territory in winter as they adopted heavier hulls and more effective types of sail.
The parallel with land travel suggests another reason sea travel decreased in winter. Medieval ship crews did not generally head out across open sea if possible--they much preferred to more or less hug the coastline (obviously at a safe distance). A big reason for this was the ability to row ashore frequently to resupply. That would of course be more difficult and much more expensive in winter, if it were even possible. Relatedly, although I've not read this specifically, I suspect it was riskier to sail closer to the coastline in winter for fear of being wrecked on the shore/coastal islands, especially with low visibility.
Considering history through a prism of human ecology, too, helps explain why technological innovations rarely have one immediate massive impact, as with the introduction of various types of heavier ship, more effective sails, better navigational methods. There are a lot of factors in play and a lot of habits to change--adapting to one piece of the puzzle does not necessarily mean an adequate response to all of them.
You might find Pryor's Geography, Technology, and War useful (it's about medieval Mediterranean ships and shipping), if you're interested in pursuing this topic or similar ones further. But there's also a good amount on this topic available on academia.edu--I Googled "medieval mediterranean winter sailing" for the heck of it and turned up plenty of information about weather conditions for sea travel. (This one's focused on antiquity, but has the full Vegetius passage I excerpted above if you're curious))
Good luck with your thesis!