.jpg)
Acog is a type ofship that was used during theMiddle Ages, mostly for trade and transport but also in war. It first appeared in the 10th century, and was widely used from around the 12th century onward. Cogs wereclinker-built, generally ofoak. Cogs were fitted with a singlemast and a singlesquare sail. They were used primarily for trade in north-west medieval Europe, especially by theHanseatic League. Typical seagoing cogs were from 15 to 25 meters (49 to 82 ft) long, 5 to 8 meters (16 to 26 ft) wide, and were of 30–200tons burthen. Cogs were rarely as large as 300 tons although a few were considerably larger, over 1,000 tons.
Although the name cog is recorded as early as the 9th century, the seagoing vessel of that name seems to have evolved on theFrisian coast during the 12th century. Cogs progressively replacedViking-type vessels such asknarrs in northern waters during the 13th century. Cogs could carry more cargo than knarrs of a similar size. Their flat bottoms allowed them to settle on a level in harbour, making them easier to load and unload. Their high sides made them more difficult to board in a sea fight, which made them safer from pirates.
Cogs were a type of round ship,[1] characterized by a flush-laid flat bottom at midships which gradually shifted to overlappedstrakes near the posts. They were propelled by a single, large, rectangular sail. Typical seagoing cogs ranged from about 15 to 25 meters (49 to 82 ft) in length with a beam of 5 to 8 meters (16 to 26 ft) and were 40–200tons burthen. Cogs were rarely as large as 300 tons, although a very small number were considerably larger, over 1,000 tons.[2][3][4][5] A rule of thumb forcrew size was that one sailor, exclusive of any dedicated fighting men, was required for every 10tons burthen of the cog, although this may generate a suggested crew size on the low side ofMedieval practice.[6] Crews of up to 45 for civilian cogs are recorded, and 60 for a 240-ton cog being used for military transportation.[7]
Cogs were typically constructed largely ofoak, and had fulllapstrake, or clinker, planking covering their sides, generally starting from the bilgestrakes, withdouble-clenchediron nails for plank fastenings. At thestem,chases are formed; that is, in each case, theland of the lower strake is tapered to a feather edge at the end of the strake where it meets the stem orstern-post. This allows the end of the strake to be fastened to theapron with the outside of the planking mutually flush at that point and flush with the stem. This means that the boat's passage through the water will not tend to lift the ends of the planking away from the stem. Before the next plank is fitted, the face of theland on the lower strake isbevelled to suit the angle at which the next strake will lie in relation with it. This varies all along the land. The new strake is held in position on the preceding one before the fastening is done.[8][9]
Thekeel, or keel-plank, was only slightly thicker than the adjacentgarboards and had norabbet. Both stem and stern-posts were straight and rather long, and connected to the keel-plank through intermediate pieces calledhooks. The lower plankhoods terminated inrabbets in the hooks and posts, but upper hoods were nailed to the exterior faces of the posts.Caulking was generallytarredmoss that was inserted into curved grooves, covered with woodenlaths, and secured by metalstaples calledsintels.[8] The cog-built structure would be completed with astern-mounted, hanging, centralrudder on a heavy stern-post, which was a uniquely northern development.[10] The single, thick,mast was set forward of amidships, stepped into the keel-plank and equipped with a single large, rectangular,square-riggedsail.[11][9] The masts of larger vessels would be of composite construction.[12] Complicated systems ofrigging were developed to support the mast and to operate the sail.[13]Cordage was usuallyhemp orflax[note 1] and the sail hemp-basedcanvas.[14] From the 13th century cogs would be decked and larger vessels would be fitted with astern castle, to afford more cargo space by keeping the crew and tiller up, out of the way; and to give thehelmsman a better view.[15]
.JPG)
A cog, compared with thecarvel-built vessels more traditional in the Mediterranean, was expensive and required specialistshipwrights. However, their simpler sail setup meant that cogs only required half the crew of similar-sized vessels equipped with lateen sails, as were common in the Mediterranean.[16] A structural benefit of clinker construction is that it produces a vessel that can safely twist and flex around its long axis (running from bow to stern), which is an advantage in North Atlanticrollers, provided the vessel has a small overalldisplacement. A limitation of cogs is that they lack points to mount additional masts: at least some fore-and-aft sails are desirable for maneuverability but clinker-built cogs were effectively limited to a single sail.[17][18] This made them unhandy, limiting their ability to tack in the harbour and making them very reliant on wind direction at the start of voyages.[17][19] The flat bottom permitted cogs to be readily beached and unloaded at low tide whenquays were not available; a useful trait when purpose-builtjetties were not common.[11] Cogs were expected to have a working life of approximately 40 years.[4][note 2]
The earliest origins of the cog are believed to belogboats from around northern Germany. These developed into larger craft built in the same basic shape, but with planking instead of hollowed-out logs. Another development was intoKahnen,flat-bottomed boats, with pointed ends for and aft that were constructed by splitting a hollowed-out log and widening the bottom with planks that were nailed to knee-shapedribs attached to the sides. The pointed ends (calledBlock locally) of the log would be cut off and attached separately to the widened hull which resulted in so-calledBlockkahnen, variants of which are still in use. The earliest evidence of a cog-like craft is a clay model found inLeese on the middleWeser from the grave of an adult male who died around 200 BC. Fragments of similar clay models have been found in nearby regions.[20]
Trade fromGermania in Roman times was mostly carried on Mediterranean-style sailing vessels and controlled by Roman merchants. After Roman power collapsed in the middle of the first millennium AD, transports on the large river estuaries and the sheltered waters of theWadden Sea was taken over byFrisians who used vessels based on indigenous, flat-bottomed designs that were precursors of later medieval cogs. These had much lower sides than later cogs and would have been very similar to contemporary Scandinavian craft, such asknarrs. The oldest depiction of a vessel identified by contemporary sources as a cog is theLübeck city seal from 1223. The early cogs were fitted with a side-mountedrudder oar that also functioned as aleeboard and was rigged with a single broad square sail that functioned similar to alug sail.[21]
Around 1200, the side rudder began to be replaced with a centerline rudder attached to asternpost and developed in the typical medieval cog. Cogs could carry more cargo than knarrs; the rudder made steering easier than did the steering oar of the knarr, especially for larger vessels; and cogs were cheaper to build. The latter was due to the cog's use ofsawn rather thansplit planks which was less wasteful.[15] Fore and stern castles would later be added for defense againstpirates, or to enable the use of these vessels as warships.[22] The stern castle also afforded more cargo space below by keeping the crew and tiller up, out of the way.
Current archaeological evidence points to theFrisian coast or WesternJutland as the possible birthplace of this type of vessel. The transformation of the cog into a true seagoing trader came not only during the time of the intense trade between West and East but also as a direct answer to the closure of the western entrance to theLimfjord. For centuries, the Limfjord in northern Jutland offered a fairly protected passage between theNorth Sea and the Baltic. Due to its unusual geographical conditions and strong currents, the passage was constantly filling with sand and was completely blocked by the early 12th century. This change produced new challenges. The larger ships, which could not be pulled across the sand bars, had to sail around the Jutland peninsula and circumnavigate the dangerous CapeSkagen to get to the Baltic.[23] This resulted in major modifications to old ship structures, which can be observed by analyzing the evolution of the earliest cog finds of Kollerup, Skagen, and Kolding. This caused a boom in the number of small cogs, and the need for spacious and seaworthy ships led to the development of the cog as the workhorse of theHanseatic League.[23] It soon became the main cargo carrier in Atlantic and Baltic waters.[18][24]
Eventually, around the 14th century, the cog reached its structural limits, and larger or more seaworthy vessels needed to be of a different type. This was thehulk, which already existed but was much less common than the cog. There is no evidence that hulks descended from cogs, but it is clear that a lot of technological ideas were adapted between the two types.[10] The transition from cogs to hulks was not linear, according to some interpretations, both vessels coexisted for many centuries but followed diverse lines of evolution.[25]
The first archaeological find that was identified as a cog, was a ship wreck discovered in 1944 by P. J. R. Modderman in theNoordoostpolder nearEmmeloord (plot NM 107). The wreck was reburied in situ and a 2008 re-excavation confirmed the interpretation as a cog. It was around 16 m long and its wood dated from 1339. The discovery by Modderman was however not well known in the literature.[26]
The most famous cog in existence today is theBremen cog. The artifact originates from the 1380s and was discovered in 1962. Prior to this discovery, the existence of cogs was primarily documented in medieval texts and seals. In 1990 the well-preserved remains of a Hanseatic cog were discovered in the estuary sediment of thePärnu River inEstonia which has been dated to 1300.[27] In 2012, a cog dating from the early 15th century was discovered preserved from the keel up to the decks in the silt of the RiverIJssel in the city ofKampen,Netherlands.[28] During its excavation and recovery an intact brick dome oven and glazed tiles were found in the galley as well as a number of other artifacts.[29][30]
In April 2022, a 13th-century cog was found in Tallinn, Estonia during highway construction. It is believed to be better preserved than the Bremen cog and adendrochronology test on the wood has dated the wreck to 1298. The ship is 24 meters long and nine meters wide. The boards are intact up to three meters from the bottom of the ship.[31]
