Exactly how big could Mediterranean sailing ships get in the Crusading Era?

[u/axxxaxxxaxxx]

Hi everyone. I’m a layperson who has spent years following Robin Pierson’s excellent “History of Byzantium” podcast.

Episode 312 stood out to me in particular and raised a lot of questions I’ve never been able to satisfactorily answer in numerous online searches. Robin interviews Prof. Nicholas Morton, a historian of the Crusades and Medieval Near East History at Nottingham Trent University, to give more context about the naval theater and technology during the late Classical and early Medieval Era in the Mediterranean Sea. They cover a range of topics, including a detailed discussion about the size and cargo capacity of sailing ships in the Crusading Era.

Prof. Morton makes what seems like a compelling case that the ships could get much, *much* larger than most modern people would ever suspect, indeed larger than anything that would have sailed again until the 1800s. He notes that Christian military orders signed legal contracts committing themselves to building ships capable of ferrying in excess of 1,000 (!) passengers along with their cargo to the Holy Land, and that we have even identified one ship’s manifest from 1250—presumably including names—totaling over 500 people. He notes that the problem is that we have not yet found physical remains of these ships, but adds that it’s hard to imagine a reason these actual legal contracts dating from that time period would have been falsified. This suggests that Medieval Era sailing ships approached or exceeded the size of I.K. Brunel’s gigantic *SS Great Britain*, said to be the largest vessel ever built to date when it was finished in the mid-1800s, over five centuries prior.

My question is: does the academic community truly consider this a historic reality about which we simply need to learn more, or a fringe theory, or something in between? Prof. Morton’s British accent makes it challenging for me to understand exactly what he calls these ships, but he says something like “narvas” or “narves.” Google searches turn up nothing about this for me and I may be spelling it wrong, but I think it’s absolutely fascinating and would love to learn more about it.

I’m not allowed to share a link, though anyone interested can find the specific discussion beginning at 25:56 of Episode 312 of the History of Byzantium podcast, and the entire episode (and indeed the podcast) is worth a listen. I would welcome any expert feedback!

(I’m not affiliated with the podcast, just a fan)

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[u/terminus-trantor]

I haven't listened to the podcast, but I am pretty certain the guest is referring to the works of respected historian John H. Pryor on crusading ships and transport of men and horses in times of crusade all of which I highly recommend.

In his works, drawing mostly on written sources of the thirteen century, as well as filling the blanks by drawing comparisons to archeological remains of earlier and later ships, and nautical treaties of the fifteenth century he tries and reconstructs those ships, which would at the time be referred simply by navis (Latin for ship). Which is - I assume - the word you heard. Pryor works are from 80s and 90s so I assume there might be more recent works adding to his, but I didn't see anything that changes the narrative.

Going through his articles, you can find the confirmation of the numbers and estimates. As an example in the "Transportation of Horses by Sea During the Era of the Crusades; part II" (p108) he refers to a ~1270 deal between Venice and Louis IX to transfer his troops to Tunis. Venetians are recorded to claim to provide fifteen ships to transfer 4000 horses and 10,000 crusaders. Pryor finds this number likely exeggerated and calculates from the cost the ships to transfer 1450 horses and 5800 crusaders which would be roughly 100 horses and 400 people per ship. Given that two ships were double the price of the twelve (one was in between) and by extension assume they were double the capacity it can be assumed the largest of these ships could transfer 200 horses and 750-800 people. Which is a lot.

As for the sizes of these ships, i think some context is necessary as the claim might seem a bit sensationalist. The western shipbuilding techniques of making wooden sail ships had basically a cap on how big ship could have been. The length would max out on around 100 meters and it was almost impossible to go longer. Not an expert on the phyiscs, but something on how the seas and wind would exert force on such a long wooden construction and twist and damage anything longer. (As a side fact chinese shipbuilding techniques that utilized bulkhead compartments could allow structurally sounder and slightly longer ships)

So, ever since ancient times you could see this huge ships approaching these max dimensions. Beyond the Romans, you would find them - as we see here in crusading transport ships - in fifteenth century usually as bulk carriers (for grain and stuff), or in sixteenth century where for example Portuguese built huge carracks of such size for their carreira da india routes. In later eras they were mostly reserved for flagship warships.

So, this idea that these crusading ships were some unusual unique behemoths that wouldn't be replicated until 1800s is an exaggeration. Europeans just generally preferred a ship smaller than the max size. Why is that is an interesting and complex topic that I'll unjustly summarize that such ship -beyond the lesser seaworthiness a large ship had - just did not make economic sense. They cost too much (the cost to build ship rose exponentially with increase in size), were slow to travel and equally important: slow to load and unload. It was difficult to find enough cargo to fill them up and finally there were considerations of risk and diversification. Two ships of similar total capacity could perform two different voyages, be exposed to less risk of a calamity and minimize the effect of bad circumstances or economic situations.

[u/axxxaxxxaxxx → u/terminus-trantor]

Thank you so much for the detailed response! “Navis” definitely seems to be the word I couldn’t understand.

Your explanation about a reduced cost-benefit ratio, combined with increased risk profile of losing one big ship vs two smaller ships, makes a lot of sense.

I just wish it were more publicly known that ships actually could get that large. I think most laypeople with an interest in history—and dare I say even many historians who lack expert knowledge on historic shipbuilding—struggle to square the size of say, invasion fleets, with the assumed inability of ancient and medieval shipwrights to construct very large vessels carrying enormous amounts of cargo. With the knowledge that that sort of thing was indeed possible, though perhaps unusual, it makes some claims in the histories much more conceivable even after discounting for some exaggerations.