This article possibly contains original research .(November 2021) |
Clinker-built (also known as lapstrake) [1] [2] is a method of boat building in which the edges of hull planks overlap each other. Where necessary in larger craft, shorter planks can be joined end to end, creating a longer strake or hull plank.
The technique originated in Scandinavia, and was employed by the Anglo-Saxons, Frisians, and Scandinavians. It was used in the vessels known as cogs, employed by the Hanseatic League. Carvel construction, where plank edges are butted smoothly, seam to seam, supplanted clinker construction in large vessels as the demand for capacity surpassed the limits of clinker construction, such as in the larger hulks. (See Comparison between clinker and carvel below.). [3]
Examples of clinker-built boats that are directly descended from those of the early medieval period are seen in the traditional round-bottomed Thames skiffs, and the larger (originally) cargo-carrying Norfolk wherries of England. [4]
From clinch, or clench, a common Germanic word, meaning “to fasten together”. [5]
The technique of clinker developed in the Nordic shipbuilding tradition as distinct from the Mediterranean mortise and tenon planking technique which was introduced to the provinces of the north in the wake of Roman expansion. Although overlapping seems to already appear in the 4th-century BC Hjortspring boats, [6] the oldest evidence for a clinker-built vessel, dendrochronologically dated to 190 AD, are boat fragments which were found in excavations at the site of the Nydam Boat. [7] The Nydam Boat itself, built c. 320 AD, is the oldest preserved clinker-built boat. [8] Clinker-built ships were a trademark of Northern European navigation throughout the Middle Ages, particularly of the longships of the Viking raiders and traders, as well as the trading cogs of the Hanseatic League. Clinker-built vessels were constructed as far South as the Basque country. [lower-alpha 1] [9]
In building a simple pulling boat, workers assemble and securely set up the keel, hog, stem, apron, deadwoods, sternpost and perhaps transom. [lower-alpha 2] In normal practice, this will be the same way up as they will be in use. From the hog, the garboard, bottom, bilge, topside and sheer strakes are planked up, held together along their ‘lands’ – the areas of overlap between neighbouring strakes – by copper rivets. At the stem and, in a double-ended boat, the sternpost, geralds 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. This allows the end of the strake to be screwed to the apron 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 laid up, 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 varies all along the land. Gripes are used to hold the new strake in position on the preceding one before the fastening is done.
Once the shell of planking is assembled, transverse battens of oak, ash, or elm, called timbers, are steam-bent to fit the internal, concave side. Elm species are not durable where the boat is used frequently in fresh water. As the timbers are bent in, they are copper-riveted to the shell, through the lands of the planking.
On many clinker-built craft, e.g. in Scandinavia and in Thames skiffs and larger working craft like the coble, sawn frames are used, assembled from floors and top timbers, joggled to fit the lands. Sometimes the timbers in larger archaic craft were also joggled before being steamed in.
With the timbers all fitted, longitudinal members are bent in. The ones that run on the underside of the thwarts are called risings. [10] : 211 They are fastened through the timbers. Bilge keels are often added to the outside of the land on which the boat would lie on a hard surface to stiffen it and protect it from wear. A stringer is usually fitted round the inside of each bilge to strengthen it. In a small boat, this is usually arranged to serve also as a means of retaining the bottom boards. These are removable assemblies, shaped to lie over the bottom timbers and be walked upon. They spread the stresses from the crew's weight across the bottom structure.
Inboard of the sheer strake the heavier gunwale is similarly bent in along the line of the sheer. This part of the work is finished by fitting the breast hook and quarter knees. Swivel or crutch chocks are fitted as appropriate to the gunwale, the thwarts fitted down onto the rising and held in position by knees up to the gunwale and perhaps down onto the stringer. The structure of gunwale, rising, thwart and thwart knees greatly stiffens and strengthens the shell and turns it into a boat. There are several ways of fixing the rubbing strake, but, in a clinker boat, it is applied to the outside of the sheer strake.
Finally, the fittings such as swivels or crutch plate, painter ring, stretchers, keel and stem band are fitted and fixed with screws. In a sailing dinghy, there would be more fittings, such as fairleads, horse, shroud plates, mast step, toe straps and so on.
At stages along the way, painters will have been called in to prime the timber, particularly immediately before the timbering is done. The boatbuilder will clean up the inside of the planking and the painter will prime it and probably more, partly because it is easier that way and partly so as to put some preservative on the planking behind the timbers. Similarly, it is best to have the varnishing done after the fittings are fitted but before they are shipped. Thus, the keel band will be shaped and drilled and the screw holes drilled in the wood of keel and stem then the band will be put aside while the varnishing is done.
The planks may be fastened together in several ways:
In the last few years of wooden boat construction, glue and screws took over, but until the 1950s, the keel, hog, stem, apron, deadwoods, sternpost, and perhaps transom would be fastened together by bolts set in white lead and grease. There are three kinds of bolt used:
Where suitable metal was not available, it was possible to use treenails (pronounced trennels). They were like clench bolts but made of wood, and instead of being clenched, they had a hardwood wedge knocked into each end to spread it. The surplus was then sawn off.
The Vikings used the clinker form of construction to build their longships from split wood planks. Clinker is the most common English term for this construction in both British and American English, though in American English the method is sometimes also known as lapstrake; lapboard was used especially before the 20th century to side buildings, where the right angles of the structure lend themselves to quick assembly.
The smoother surface of a carvel boat gives the impression at first sight that it is hydrodynamically more efficient. The lands of the planking are not there to disturb the stream line. This distribution of relative efficiency between the two forms of construction is an illusion because for given hull strength, the clinker boat is lighter.
Additionally, the clinker building method as used by the Vikings created a vessel which could twist and flex relative to the line extending length of the vessel, bow to stern. This gave it an advantage in North Atlantic rollers so long as the vessel was small in overall displacement. Increasing the beam, due to the light nature of the method, did not commensurately increase the vessel's survivability under the torsional forces of rolling waves, and greater beam widths may have made the resultant vessels more vulnerable.[ citation needed ]
There is an upper limit to the size of clinker-built vessels, which could be and was exceeded by several orders of magnitude in later large sailing vessels incorporating carvel-built construction. Clinker building requires relatively wide planking stock compared to carvel, as carvel can employ stealers to reduce plank widths amidships, where their girth is greatest, while clinker planks, needing sufficient lap to accept their clench fastenings, must be wider in proportion to their thickness. In all other areas of construction, including framing, deck, etc., clinker is as capable as carvel. Clinker construction remains to this day a valuable method of construction for small wooden vessels.
The Nordic clinker boat tradition was inscribed to the UNESCO List of the Intangible Cultural Heritage on December 14, 2021, as the first joint Nordic application to the list. [12]
Longships were a type of specialised Scandinavian warships that have a long history in Scandinavia, with their existence being archaeologically proven and documented from at least the fourth century BC. Originally invented and used by the Norsemen for commerce, exploration, and warfare during the Viking Age, many of the longship's characteristics were adopted by other cultures, like Anglo-Saxons, and continued to influence shipbuilding for centuries.
The koch was a special type of small one- or two-mast wooden sailing ships designed and used in Russia for transpolar voyages in ice conditions of the Arctic seas, popular among the Pomors.
A cog was a type of ship that was used during the Middle 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 were clinker-built, generally of oak. Cogs were fitted with a single mast and a single square sail. They were used primarily for trade in north-west medieval Europe, especially by the Hanseatic League. Typical seagoing cogs were from 15 to 25 meters long, 5 to 8 meters wide, and were of 30–200 tons burthen. Cogs were rarely as large as 300 tons although a few were considerably larger, over 1,000 tons.
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.
Boat building is the design and construction of boats — and their on-board systems. This includes at minimum the construction of a hull, with any necessary propulsion, mechanical, navigation, safety and other service systems as the craft requires.
Strip-built, or "strip-plank epoxy", is a method of boat building. Also known as cold molding, the strip-built method is commonly used for canoes and kayaks, but also suitable for larger boats. The process involves securing narrow, flexible strips of wood edge-to-edge around temporary formers. The temporary formers are usually created via a process called "lofting" whereby a set of tables is used to generate the shapes of the formers. The strips are glued edge-to-edge with epoxy. It is effectively a modern form of carvel which needs no caulking and which is both stiffer and more watertight. In a small boat, there will be just one layer of strip-planking, but larger vessels may have two or three layers which,, forms a light, strong, and torsionally stiff monococque.
The Gokstad ship is a 9th-century Viking ship found in a burial mound at Gokstad in Sandar, Sandefjord, Vestfold, Norway. It is displayed at the Viking Ship Museum in Oslo, Norway. It is the largest preserved Viking ship in Norway.
On a vessel's hull, a strake is a longitudinal course of planking or plating which runs from the boat's stempost to the sternpost or transom. The garboard strakes are the two immediately adjacent to the keel on each side.
The Hjortspring boat is a vessel designed as a large canoe, from the Scandinavian Pre-Roman Iron Age. It was built circa 400–300 BC. The hull and remains were rediscovered and excavated in 1921–1922 from the bog of Hjortspring Mose on the island of Als in Sønderjylland, southern Denmark. The boat is the oldest find of a wooden plank ship in Scandinavia and it closely resembles the thousands of petroglyph images of Nordic Bronze Age ships found throughout Scandinavia. The vessel is a clinker-built wooden boat of more than 19 metres length overall, 13.6 metres long inside, and 2 metres wide. Ten thwarts that could have served as seats, span the boat with room for two persons each; this suggests space for a crew of at least 20 who propelled the boat with paddles. The boat would have weighed an estimated 530 kilograms, making it easily portable by its crew.
The Fifie is a design of sailing boat developed on the east coast of Scotland. It was a traditional fishing boat used by Scottish fishermen from the 1850s until well into the 20th century. These boats were mainly used to fish for herring using drift nets, and along with other designs of boat were known as herring drifters.
The Bevaix boat is a 1st-century Gallo-Roman wreck from the Bay of Bevaix, Lake Neuchâtel, Switzerland. The remains of the ship, and a modern reconstruction, are on display at the Laténium archeology museum.
The Edna E. Lockwood is a Chesapeake Bay bugeye, the last working oyster boat of her kind. She is located at the Chesapeake Bay Maritime Museum in Saint Michaels, Maryland. She was built in 1889 at Tilghman Island, Maryland by John B. Harrison and is of nine-log construction, similar to the smaller log canoe, and was launched on October 5, 1889, for Daniel Haddaway, at a cost of $2,200. She worked for at least seven sets of owners from 1899 until 1967, and was then sailed as a yacht until donated to the museum in 1973. The museum undertook an extensive restoration of the Lockwood from 1975 through 1979, which restored the bugeye to its 1910 appearance with the "patent stern" that had been added sometime prior to that year. She is the last bugeye retaining the sailing rig and working appearance of the type. Her length is 53.5 feet (16.3 m), with a 15.25 feet (4.65 m) beam and a draft of 2.58 feet (0.79 m) with the centerboard up, and a maximum sail area of approximately 1700 square feet.
The Humber keel was a type of single-masted, square-rigged sailing craft used for inshore and inland cargo transport around Hull and the Humber Estuary, in the United Kingdom, particularly through the late 19th and early 20th centuries.
A hulk was a type of medieval ship used mostly for transports. The hulk appears to have remained a relatively minor type of sailing ship apparently peculiar to the Low Countries of Europe where it was probably used primarily as a river or canal boat, with limited potential for coastal cruising. The only evidence of hulks is from legal documents and iconography, though it is possible that a shipwreck found on the coast of Estonia in early 2022 might be the only known surviving example of a hulk.
The Sparrow-Hawk was a 'small pinnace' similar to the full-rigged pinnace Virginia that sailed for the English Colonies in June 1626. She is the earliest ship to participate in the first decades of English settlement in the New World to have survived to the present day.
Fusi Yama was a composite barque ship of roughly 556 tons, built in 1865 by Alexander Stephen & Sons at Glasgow for Killick Martin & Company, London.
Lashed-lug boats are ancient boat-building techniques of the Austronesian peoples. It is characterized by the use of raised lugs on the inner face of hull planks. These lugs have holes drilled in them so that other hull components such as ribs, thwarts or other structural components can be tied to them with natural fiber ropes. This allows a structure to be put together without any metal fastenings. The planks are further stitched together edge-to-edge by sewing or using dowels ("treenails") unto a dugout keel and the solid carved wood pieces that form the caps for the prow and stern. Characteristically, the shell of the boat is created first, prior to being lashed unto ribs. The seams between planks are also sealed with absorbent tapa bark and fiber that expands when wet or caulked with resin-based preparations.
A Woods Hole spritsail boat is a small sailing and rowing craft, constructed entirely of wood, and fastened with iron or copper. It was used historically for fishing, island mail deliveries, racing, or day sailing off the coast of southeastern Massachusetts, especially in the waters of Buzzards Bay and Vineyard Sound near the town of Woods Hole, a community of Falmouth in Barnstable County, Massachusetts. Although the sprit sailing rig has ancient roots, the Woods Hole spritsail boats were built and used mainly in the period between the US Civil War and World War I, becoming most prevalent during the late 19th and early 20th centuries. The original boats were employed almost exclusively in fishing, including handlining for finfish, trap fishing for lobster, or digging with tongs for bivalve shellfish, but by the late 19th century, newer and lighter spritsail boats began to be built for recreational sailing and racing. This transition coincided with the emergence of Woods Hole as a summer coastal tourist destination, when the Cape Cod Central Railroad began service from Buzzards Bay in 1872, followed by a private subscription railroad that was extended from Boston in 1884. This spritsail boat has now disappeared as a type, but its cultural significance endures in New England maritime museums, remaining a material symbol of the small community of Woods Hole.
The Columbia boat was a type of inland boat used to carry furs, trade goods, supplies, and passengers along the Columbia River during the fur trade era, c. 1811–1845. It needed to be large enough to carry substantial cargo, light enough to portage around such obstacles as falls and rapids, and made of locally sourced materials. It was modeled after the birchbark canoe used in waterways east of the Rocky Mountains, but was sheathed with thin cedar planks.