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Cog (ship)
Encyclopedia
A cog is a type of ship that first appeared in the 10th century, and was widely used from around the 12th century on. Cogs were generally built of oak
, which was an abundant timber in the Baltic
region of Prussia
. This vessel was fitted with a single mast
and a square-rigged single sail. These vessels were mostly associated with seagoing trade in medieval Europe
, especially the Hanseatic League
, particularly in the Baltic Sea
region.
Cogs were characterized by a flush-laid flat bottom at midships but gradually shifted to overlapped strake
s near the posts. They had full lapstrake
planking covering the sides, generally starting from the bilge strakes, and double-clenched iron
nails for plank fastenings. The keel
, or keelplank, was only slightly thicker than the adjacent garboards and had no rabbet
. Both stem and stern posts
were straight and rather long, and connected to the keelplank through intermediate pieces called hooks. The lower plank hoods terminated in rabbets in the hooks and posts, but upper hoods were nailed to the exterior faces of the posts. Caulking
was generally tarred moss that was inserted into curved grooves, covered with wooden laths, and secured by metal staples called sintels. Finally, the cog-built structure could not be completed without a stern-mounted hanging central rudder, which was a unique northern development. Cogs used to have open hulls and could be rowed short distances. In the 13th century they received decks. The most famous is the Bremen cog.
near Amsterdam. These early cogs were influenced by the Norse Knarr
, which was the main trade vessel in northern Europe at the time, and probably used a steering oar, as there is nothing to suggest a stern rudder in northern Europe until about 1240.
Current archaeological evidence points to the Frisia
n coast, Western Jutland
, 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 the Limfjord
. For centuries, Limfjord in northern Jutland offered fairly protected passage between the North Sea
and the Baltic. Due to unusual geographical conditions and strong currents, the passage was constantly filling with sand and was completely blocked by the 12th century. This change produced new challenges. Bigger ships that could not be pulled across the sand bars had to sail around the Jutland peninsula and circumnavigate the dangerous Cape Skagen
to get to the Baltic. This resulted in major modifications to old ship structures, which can be observed by analyzing evolution of the earliest cog finds of Kollerup, Skagen, and Kolding.
The need for spacious and relatively inexpensive ships led to the development of the first workhorse of the Hanseatic League
, the cog. The new and improved cog was no longer a simple Frisian coaster but a sturdy seagoing trader, which could cross even the most dangerous passages. Fore and stern castles would be added for defense against pirates, or to enable use of these vessels as warships, such as used at the Battle of Sluys
.
Eventually, around the 14th century, the cog reached its structural limits, resulting in the desperate need for a quick replacement. The replacement, the hulk
, already existed but awaited reconditioning. Although there is no evidence that hulks descended from the cogs, it is clear that a lot of technological ideas were adapted from one to the other and vice versa. 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.
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, which was an abundant timber in the Baltic
Baltic region
The terms Baltic region, Baltic Rim countries, and Baltic Rim refer to slightly different combinations of countries in the general area surrounding the Baltic Sea.- Etymology :...
region of Prussia
Prussia (region)
Prussia is a historical region in Central Europe extending from the south-eastern coast of the Baltic Sea to the Masurian Lake District. It is now divided between Poland, Russia, and Lithuania...
. This vessel was fitted with a single mast
Mast (sailing)
The mast of a sailing vessel is a tall, vertical, or near vertical, spar, or arrangement of spars, which supports the sails. Large ships have several masts, with the size and configuration depending on the style of ship...
and a square-rigged single sail. These vessels were mostly associated with seagoing trade in medieval Europe
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...
, especially the Hanseatic League
Hanseatic League
The Hanseatic League was an economic alliance of trading cities and their merchant guilds that dominated trade along the coast of Northern Europe...
, particularly in the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
region.
Design
Strake
A strake is part of the shell of the hull of a boat or ship which, in conjunction with the other strakes, keeps the sea out and the vessel afloat...
s near the posts. They had full lapstrake
Clinker (boat building)
Clinker building is a method of constructing hulls of boats and ships by fixing wooden planks and, in the early nineteenth century, iron plates to each other so that the planks overlap along their edges. The overlapping joint is called a land. In any but a very small boat, the individual planks...
planking covering the sides, generally starting from the bilge strakes, and double-clenched iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
nails for plank fastenings. The keel
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
, or keelplank, was only slightly thicker than the adjacent garboards and had no rabbet
Rabbet
A rabbet is a recess or groove cut into the edge of a piece of machineable material, usually wood. When viewed in cross-section, a rabbet is two-sided and open to the edge or end of the surface into which it is cut....
. Both stem and stern posts
Sternpost
A sternpost is the upright structural member or post at the stern of a ship or a boat, to which are attached the transoms and the rearmost left corner part of the stern...
were straight and rather long, and connected to the keelplank through intermediate pieces called hooks. The lower plank hoods terminated in rabbets in the hooks and posts, but upper hoods were nailed to the exterior faces of the posts. Caulking
Caulking
Caulking is one of several different processes to seal joints or seams in various structures and certain types of piping. The oldest form of caulking is used to make the seams in wooden boats or ships watertight, by driving fibrous materials into the wedge-shaped seams between planks...
was generally tarred moss that was inserted into curved grooves, covered with wooden laths, and secured by metal staples called sintels. Finally, the cog-built structure could not be completed without a stern-mounted hanging central rudder, which was a unique northern development. Cogs used to have open hulls and could be rowed short distances. In the 13th century they received decks. The most famous is the Bremen cog.
History
Cogs are first mentioned in 948 AD, in MuidenMuiden
Muiden is a municipality and a town in the Netherlands, in the province of North Holland. It lies at the mouth of the Vecht and is in an area called the Vechtstreek.-Population centres :...
near Amsterdam. These early cogs were influenced by the Norse Knarr
Knarr
The Knarr is a Bermuda rigged, long keeled, sailing yacht designed in 1943 by Norwegian Erling L. Kristofersen. Knarrer were traditionally built in wood, with the hull upside down on a fixed frame, then attaching the iron keel after the hull was completed. The hull planks were manufactured with...
, which was the main trade vessel in northern Europe at the time, and probably used a steering oar, as there is nothing to suggest a stern rudder in northern Europe until about 1240.
Frisia
Frisia is a coastal region along the southeastern corner of the North Sea, i.e. the German Bight. Frisia is the traditional homeland of the Frisians, a Germanic people who speak Frisian, a language group closely related to the English language...
n coast, Western Jutland
Jutland
Jutland , historically also called Cimbria, is the name of the peninsula that juts out in Northern Europe toward the rest of Scandinavia, forming the mainland part of Denmark. It has the North Sea to its west, Kattegat and Skagerrak to its north, the Baltic Sea to its east, and the Danish–German...
, 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 the Limfjord
Limfjord
The Limfjord is a shallow sound in Denmark that separates the island of Vendsyssel-Thy from the rest of the Jutland Peninsula. It extends from Thyborøn Channel on the North Sea to Hals on the Kattegat. It is approximately 180 kilometres long and of an irregular shape with several bays, narrowings,...
. For centuries, Limfjord in northern Jutland offered fairly protected passage between the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
and the Baltic. Due to unusual geographical conditions and strong currents, the passage was constantly filling with sand and was completely blocked by the 12th century. This change produced new challenges. Bigger ships that could not be pulled across the sand bars had to sail around the Jutland peninsula and circumnavigate the dangerous Cape Skagen
Skagen
Skagen is a projection of land and a town, with a population of 8,515 , in Region Nordjylland on the northernmost tip of Vendsyssel-Thy, a part of the Jutland peninsula in northern Denmark...
to get to the Baltic. This resulted in major modifications to old ship structures, which can be observed by analyzing evolution of the earliest cog finds of Kollerup, Skagen, and Kolding.
The need for spacious and relatively inexpensive ships led to the development of the first workhorse of the Hanseatic League
Hanseatic League
The Hanseatic League was an economic alliance of trading cities and their merchant guilds that dominated trade along the coast of Northern Europe...
, the cog. The new and improved cog was no longer a simple Frisian coaster but a sturdy seagoing trader, which could cross even the most dangerous passages. Fore and stern castles would be added for defense against pirates, or to enable use of these vessels as warships, such as used at the Battle of Sluys
Battle of Sluys
The decisive naval Battle of Sluys , also called Battle of l'Ecluse was fought on 24 June 1340 as one of the opening conflicts of the Hundred Years' War...
.
Eventually, around the 14th century, the cog reached its structural limits, resulting in the desperate need for a quick replacement. The replacement, the hulk
Hulk (medieval ship type)
A hulk was a type of medieval sea craft, a technological predecessor of the carrack and caravel. The hulk appears to have remained a relatively minor type of ship apparently peculiar to the low countries of Europe where it was probably used primarily as a river or canal boat, with limited...
, already existed but awaited reconditioning. Although there is no evidence that hulks descended from the cogs, it is clear that a lot of technological ideas were adapted from one to the other and vice versa. 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.