#Pictures of cogs full#

Ĭross-section of hull note the lower mast stepped and bracedĪ cog, compared with the carvel-built vessels more traditional in the Mediterranean, was expensive and required specialist shipwrights.

From the 13th century cogs would be decked and larger vessels would be fitted with a stern castle, to afford more cargo space by keeping the crew and tiller up, out of the way and to give the helmsman a better view. Cordage was usually hemp or flax and the sail hemp-based canvas. Complicated systems of rigging were developed to support the mast and to operate the sail. The masts of larger vessels would be of composite construction. The single, thick, mast was set forward of amidships, stepped into the keelplank and equipped with a single large, rectangular, square-rigged sail. The cog-built structure would be completed with a stern-mounted, hanging, central rudder on a heavy stern-post, which was a uniquely northern development.

Caulking was generally tarred moss that was inserted into curved grooves, covered with wooden laths, and secured by metal staples called sintels. The lower plank hoods terminated in rabbets in the hooks and posts, but upper hoods were nailed to the exterior faces of the posts. Both stem and stern-posts were straight and rather long, and connected to the keelplank through intermediate pieces called hooks. The keel, or keelplank, was only slightly thicker than the adjacent garboards and had no rabbet. The new strake is held in position on the preceding one before the fastening is done.

Before the next plank is fitted, the face of the land on the lower strake is bevelled to suit the angle at which the next strake will lie in relation with it. This means that the boat's passage through the water will not tend to lift the ends of the planking away from the stem. This allows the end of the strake to be fastened to the apron with the outside of the planking mutually flush at that point and flush with the stem. At the stem, chases are formed that is, in each case, the land of the lower strake is tapered to a feather edge at the end of the strake where it meets the stem or stern-post.

#Pictures of cogs full#

Their high sides made them more difficult to board in a sea fight, which may have made them safer from pirates.Ĭogs were typically constructed largely of oak, and had full lapstrake, or clinker, planking covering their sides, generally starting from the bilge strakes, with double-clenched iron nails for plank fastenings. Their flat bottoms allowed them to settle on a level in harbour, making them easier to load and unload. Why this was the case is uncertain, but cogs could carry more cargo than knarr of a similar size. Cogs progressively replaced Viking-type ships in northern waters during the 13th century. Cogs were rarely as large as 300 tons although a few were considerably larger, over 1,000 tons.Īlthough the name cog is recorded as early as the 9th century, the seagoing vessel of that name seems to have evolved on the Frisian coast during the 12th century. 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 30–200 tons burthen. They were mostly associated with seagoing trade in north-west medieval Europe, especially the Hanseatic League. These vessels were fitted with a single mast and a square-rigged single sail. Cogs were clinker-built, generally of oak. A replica of the Bremen cog: note the stern deck, partially enclosing the hold, and the crow's nestĪ cog is a type of ship that first appeared in the 10th century, and was widely used from around the 12th century on.