Clinker (boat building) in the context of "Cog (ship)"

Carvel built or carvel planking is a method of boat building in which hull planks are laid edge to edge and fastened to a robust frame, thereby forming a smooth surface. Traditionally the planks are neither attached to, nor slotted into, each other, having only a caulking sealant between the planks to keep water out. Modern carvel builders may attach the planks to each other with glues and fixings. It is a "frame first" method of hull construction, where the shape is determined by the framework onto which the planks are fixed. This is in contrast to "plank first" or "shell first" methods, where the outer skin of the hull is made and then reinforced by the insertion of timbers that are fitted to that shape. The most common modern "plank first" method is clinker construction; in the classical period "plank first" involved joining the edges of planks with mortise and tenon joints within the thickness of the timbers, superficially giving the smooth-hull appearance of carvel construction, but achieved by entirely different means.

Compared to clinker-built hulls, carvel construction allowed larger ships to be built. This is because the fastenings of a clinker hull took all the hogging and sagging forces imposed by the ship moving through large waves. In carvel construction, these forces are also taken by the edge-to-edge contact of the hull planks.

Viking ships were marine vessels of unique structure, used in Scandinavia throughout the Middle Ages. The boat-types were quite varied, depending on what the ship was intended for, but they were generally characterized as being slender and flexible boats, with symmetrical ends with true keel. They were clinker built, which is the overlapping of planks riveted together. Some might have had a dragon's head or other circular object protruding from the bow and stern for design, although this is only inferred from historical sources. Viking ships were used both for military purposes and for long-distance trade, exploration and colonization.

In the literature, Viking ships are usually seen divided into two broad categories: merchant ships and warships, the latter resembling narrow "war canoes" with less load capacity but higher speed. However, these categories are overlapping; some transport ships would also form part of war fleets. As a rule, ship lanes in Scandinavia followed coastal waters, hence a majority of vessels were of a lighter design, while a few types, such as the knarr, could navigate the open ocean. The ship's shallow draft allowed navigation in waters only one meter deep and permitted beach landings, while its light weight enabled it to be carried over portages. The Viking ships ranged from the Baltic Sea to far from the Scandinavian homelands, to Iceland, the Faroe Islands, Greenland, Newfoundland, the Mediterranean, the Black Sea and Africa.

A whaleboat is a type of open boat that was used for catching whales, or a boat of similar design that retained the name when used for a different purpose. Some whaleboats were used from whaling ships. Other whaleboats would operate from the shore. Later whaleboats usually could operate under sail or oar - American whaling crews in particular obtained better results by making their first approach to a whale under sail, then quickly unstepping the mast and using oars thereafter.

Most whaleboats have double-ended, clinker-built hulls of light construction. The hulls were narrow and with sharp ends to achieve the best possible speed for the length of waterline. Length was between 27 and 31 feet. Beam was just over a fifth of the length. Typically they were propelled by five oars when rowed, and stepped a single removable mast when under sail. A rudder was used when under sail and a steering oar when the boat was rowed. The latter provided the manoeuvrability needed when closing with a harpooned whale.

Knarr (Old Norse: knarr; Old English: cnearr, cnear; Old High German: gnarren) were the Norse merchant and cargo ships of the Viking Age, used by Vikings for long sea voyages and during the Viking expansion. While the name etymologically suggests that it was used as a warship at times, the types from the latter half of the Viking Age were built as work boats for handling cargo; the hull of a common knarr was wider, deeper and shorter than a longship, and could take more cargo and be operated by smaller crews.

The knarr was primarily used to transport trading goods like walrus ivory, wool, timber, wheat, furs and pelts, armour, slaves, honey, and weapons. It was also used to supply food, drink, weapons and armour to warriors and traders along their journeys across the Baltic, the Mediterranean and other seas. Knarrs routinely crossed the North Atlantic carrying livestock such as sheep and horses, and stores to Norse settlements in Iceland, Greenland and Vinland as well as trading goods to trading posts in the British Isles, Continental Europe and possibly the Middle East. The knarr was constructed using the same clinker-built method as longships, karves, and faerings.