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Travel times of a laden medieval merchant ship, no coconut

Jackob

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Okay, a rough estimate, how far could a late medieval (typical fantasy setting) merchant ship travel in 2 weeks, if laden with goods, given good but not ideal wind and current conditions, travelling over the open sea?

I have plans for a game where I want the PCs to have a two-week journey, so I need to figure out how far they'll go. :p
 

seneschal

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I can't find it right off, but ICE's old Pirates! supplement listed average travel speeds in knots per type of 17th century sailing vessels. We'd be looking for slower merchant types like brigs or caravels. Per wikipedia, a brig (two masted, square-sailed vessel) could achieve 11 knots (20 mph) under best conditions, which means average travel times were much slower.

Of course, medieval cogs and carracks would be slower and less efficient
 

silburnl

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I'd say something like 50-70 miles per day would be plausible for 'good but not ideal' conditions, so 700-1000 miles for a two week voyage. That would be something like a carrack plotting a course that is mostly on a good-to-decent point of sail in open seas. A caravel would be a bit faster (say 65-85 miles/day) and a cog a bit slower (say 40-60 miles/day), mostly due to those ship types having greater or lesser ability to handle contrary winds.

Note that 'good but not ideal' over a fortnight could well include one or more days when virtually no progress is made (or even that they go backwards), but also some days when wind, tide and course all come together and they log 150+ miles between sun-shots.

Note also the open seas proviso; things get a *lot* trickier (and thus more random) when you have to worry about a lee shore or are restricted to certain bearings because of the distribution of various landmasses along your course.

Regards
Luke
 

Jesse_Lowe

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They go as far as you want them to. :D Unless they're in charge of the ship, presumably the captain has a destination in mind where he (or the ship owners) are going to make a profit. If that destination seems unusually far for a two-week voyage, well on this trip the ship has fortunate following winds; if close, lots of poor sailing conditions.
 

Hackhamster

Retired User
I can't find it right off, but ICE's old Pirates! supplement listed average travel speeds in knots per type of 17th century sailing vessels. We'd be looking for slower merchant types like brigs or caravels. Per wikipedia, a brig (two masted, square-sailed vessel) could achieve 11 knots (20 mph) under best conditions, which means average travel times were much slower.

Of course, medieval cogs and carracks would be slower and less efficient
not to be too picky, but 1 knot = 1.15 mph, so 11 knots=12.65 mph. Most medieval ships that weren't oar-powered were pretty slow (silburnl makes some good points about why), so I'd make an estimate of 5-8 knots on the average. Voyages could be delayed by weather either driving you off course or into port when you didn't want to be there, or by becalming you in an area of no wind, or trapping you in an area you couldn't get out of. For instance, the Bay of Biscay was a place that could take days or weeks to get out of if the wind was at the right quarter, and that happened to square-rigged ships during the Napoleonic era.

A good rule of thumb is that no medieval sailing ship could exceed its hull speed, which is 1.34 times the square root of the waterline in feet. Or, in other words, smaller ships sail more slowly. Since the hull speed is in essence a maximum value taking into account optimum sailing conditions, and medieval ships were not rigged in the best way to take advantage of winds that were either in the face or from the sides of the ship, you can pretty much derive a reasonable average speed by dividing the hull speed by 2.

So, a 50' cog's hull speed is 9.4 knots, for an average speed of around 5 knots.
A 75' cog's hull speed is 11.6 knots, or an average speed around 6 knots. A 100' cog's hull speed is 13.4 knots, or around 7 knots average.

So, if your intrepid adventurers decide to take a 2 week trip on a 75' vessel, they can travel 7 * 24 * 14 = 2352 nautical miles, or 2704 statute miles. Sounds great! The problem is, as silburnl brought up, this distance is the amount of distance covered by the hull meeting the water, not straight line distance, so another fudge factor of .4 to .5 times the derived distance (and here is where you can factor in captain, crew quality, and weather) can give you a more accurate distance. In this case, the crew is average and the weather is ok, so .4 * 2704 gives you 1081 miles in a straight line (from port to port).

Of course, subtract from this number if the ship puts into port or anchors at night, follows the coast, encounters sea monsters, gets lost in the fog, captain gets drunk and heads the wrong way, currents and/or winds are working against you, sails get shredded by storms, etc...
 

Jiawen

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From Gillian Hutchinson's Medieval Ships and Shipping (p. 169):
Ellmers (197: 250) has compiled a table of documented voyages with their distances and the length of time they took. From this it seems that an average 'speed made good' of three to six knots was to be expected. The difference between a sailing ship's actual speed through the water and 'speed made good' is brought about by three factors. The first is the impossibility of sailing directly into the wind. It is necessary to sail a zig-zag course ('tacking') to windward. The second is leeway. On all points of sailing, except when a vessel is running directly before the wind, there is a tendency for it to make leeway -- to be pushed sideways by the wind. The degree of leeway may be estimated by the angle of the wake that the vessel trails behind and the amount varies from ship to ship. The third factor results from the effects of tidal stream and currents, which means that the sea around Britain resembles a network of conveyor belts rather than a road.
The book is almost solely concerned with cogs, so those speeds are not necessarily applicable to caravels or other types of ship.
 

Ravenswing

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What Jiawen said. There's a huge It Depends over the whole question.

First off, anything much before the 16th century is surprisingly conjectural: the only way we know what the ships looked like are from old coins and paintings ... and you can well imagine how accurate that is. The earliest surviving architectural drawings of any European sailing ship date from the 1660s.

Secondly, popular opinion and the media give people the impression that medieval seafaring = Age of Sail technology, which was not close to the case. A good bit of the development and popularity of the caravel was that cogs were genuine beasts sailing into the wind, for instance. Square-rigged medieval merchantmen needed a great deal of sailing room for tacking or wearing if they had to do so, which greatly increased travel times.

Thirdly - and I presume you're talking a normally laden merchantman - the major factors in your scenario are not only hull type as crew size. The incredible speeds achieved by the extreme clippers also had to do with them being heavily crewed.

Fourthly, you should factor in that merely getting out of port was often a struggle; if the winds were unfavorable, ships could be trapped for weeks.

So ... let's assume a caravel, normally crewed, in good repair (the average lifespan of a medieval merchantman was only 20-25 years) decent weather, open sea (far different from the Med, for one), laden with a cargo that's not unduly heavy, with good navigational technology, without any fantasy superstitions - such as that traveling at night The Monsters Will Get You - and at a good point of sailing.

1200-1400 miles.
 

Jiawen

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First off, anything much before the 16th century is surprisingly conjectural: the only way we know what the ships looked like are from old coins and paintings ... and you can well imagine how accurate that is. The earliest surviving architectural drawings of any European sailing ship date from the 1660s.
Actually, that's not true. The Bremen cog is a mostly-complete vessel from about 1380 that has given naval historians a lot of really useful data, and given me a reason to visit Bremerhaven.

Then, there's the Mary Rose from 1510 or so. But that's after the period I'm interested in, so I don't know much about it. (I've been doing a fair amount of research about medieval ships for the game I'm writing, Blade & Crown, but even 1380 is out of the range the game's concerned with.) There may even be more examples between the Mary Rose and the 1660s; I don't actually know.

The thing I can't get data on is how often ships went in to shallower waters for the night. It seems likely that smaller vessels would've done this, wanting to avoid nasty waters when seeing wasn't good, but anything truly ocean-going (including cogs, caravels, etc.) would've stayed in deep waters pretty much as long as possible between ports. I haven't found anything that breaks down what kinds of vessels were truly ocean-going or not, though, so that makes it hard to know.
 

Ravenswing

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I'm not nearly as sold on the Bremen cog as many others are; less than 30% of the hull was intact, and the reconstructionists made a number of guesses. They're certainly as good a set of guesses as can be had, and it isn't as if there are alternatives, but that doesn't equate to proven fact. The Mary Rose is, of course, out of the medieval period and into the 16th century.

As far as how often medieval ships went inshore, probably a good bit. For one thing they weren't hugely deep-seaworthy; for another, navigation was chancy enough to make leaving land behind a dangerous thing; for a third, it isn't as if the vast majority of traffic wasn't coastal anyway; and finally, the odds of being run ashore in the dark was too great. Today sailors seek searoom, but then again there's searoom to have; in the Med or the Baltic, without lights or navigational aids, there isn't.

There are some texts which have a bearing on this. Medieval Trade In The Mediterranean World (Lopez/Raymond) has a 1250 chartering contract for a nef heading to Acre and Tripoli from Genoa, and includes the equipment with which the nef is to be fitted out: 22 anchors, with 25 anchors included for the return journey. Certainly if they expected to need replacements for their entire complement of anchors losing them was routine, and that would be so only if they anchored a lot.
 

simontmn

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For a typical laden merchantman or similar I find that 50 miles/day gives something reasonable for long term travel, or 700 miles in this case. For a faster ship 80-100 miles. Anything between 50-100 miles a day is reasonable enough. You might go to 120 miles/day or so for a good ship in good conditions - that's an average 5 mph in the intended direction, which is about the highest plausible number pre-Age of Sail. A slow ship might make 30 miles/day.

Of course plenty of factors may make travel on any particular day 0 miles, -20 miles, +150 miles, etc.
 
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