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Clinker-built, also known aslapstrake-built,[1][2] is a method ofboat building in which the edges of longitudinal (lengthwise-running)hull planks overlap each other. Where necessary in larger craft, shorter hull planks can be joined end to end, creating a longer hull plank (strake).[not verified in body]
The technique originated in Northern Europe, and was employed by theAnglo-Saxons,Frisians, andScandinavians.[when?][not verified in body] It was also used incogs, the other major ship construction type found in Northern Europe in the latter part of the medieval period.Carvel construction—where longitudinal hull planksabut edge to edge (instead of lapping)—supplanted clinker construction in large vessels as the demand for capacity surpassed the limits of clinker construction, such as in larger medieval transport ships (hulks).[3]
UNESCO named the Nordic clinker boat tradition to itsList of Intangible Cultural Heritage on December 14, 2021, in the first approval of a joint Nordic application.[4]
Clinker construction is a boat and ship-building method in which the hull planks overlap and are joined by nails that are driven through the overlap. These fastenings typically go through a metalrove over which the protruding end of the nail is deformed in a process comparable to riveting the planks together. This gives a distinctive appearance to the outside of the hull as the overlaps are obvious in the stepped nature of the hull surface.[5]: 53–54 [6]: 10–11
Clinker construction is a shell-first technique (in contrast to the frame-based nature ofcarvel). The construction sequence begins with the joining of thekeel,stem andsternpost (ortransom) and setting these in place in the build area. Thereafter, the shape of the hull is determined by the shaping and fitting of the hull planking that forms the waterproof exterior of the hull. Any reinforcingframes,thwarts or beams[a] are added after the joining of the hull planks. This may involve completely finishing the exterior planking first, or just some planking may be fitted with, for instance,floors being added whilst that part of the hull is accessible before planking is continued.[5]: 53–54
Medieval clinker construction used iron nails and roves – the latter often being a distinctive diamond shape. There are less common regional instances of planks being joined withtreenails or by sewing, but iron fastening predominated.[5]: 54 More modern boats generally use copper nails with an annular rove of the same material.[7]: 25
Historically, particularly in the traditional Nordic tradition[b], clinker construction most commonly used cleft, or radially split, oak planks. This gives a stronger piece of timber than with sawn material – not only is the grain continuous along the length of the piece, but themedullary rays are aligned in the same plane as the timber surface, so maximising the strength available. However, this timber conversion method does limit the maximum width of plank to slightly more than one third of the diameter of the tree from which it is split – the narrowest part (including any pith) and the sapwood are cut off.[5]: 53–54, 60 [9] The slightly uneven surface found on cleft timber is the reason why caulking is laid in the overlap between the hull planks during construction, often using animal hair.[8]
![[icon]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aWiki_letter_w_cropped.svg) | This sectionneeds expansion with: a more thorough, authoritative, source-derived presentation of the main examples of clinker-type boats. You can help byadding to it.(November 2024) |
Early examples of clinker-built boats include thelongships of theViking raiders and traders,[when?] and the trading cogs of theHanseatic League.[when?][citation needed] Modern examples of clinker-built boats that are directly descended from those of the early medieval period are seen in the traditional round-bottomedThames skiffs, the larger (originally) cargo-carryingNorfolk wherries of England,[11] and working craft like theyawls that were once common around the coasts of Britain and Ireland.[12]: passim
The term clinker derives from a commonGermanic word forclinch orclench, a word meaning “to fasten together”.[13]
In the first few centuries AD, several boat and ship-building systems existed in Europe. In the Mediterranean, flush-planked hulls were produced by edge-to-edge joining of the hull planking withmortise and tenon joints. This was a shell-first technique[c], which started with a keel, stem and stern-post, to which planking was added. The hull was then reinforced by the addition offrames. The shape of the individual planks generates the shape of the hull. In the Roman-occupied parts of Northern Europe, the Romano-Celtic tradition involved flush-planking that was not joined with mortise and tenon joints but was connected by framing elements. (This may be a building tradition that continued with the bottom planking of the medievalcog and then into the Dutch bottom-based building methods of the 17th century.) The Romano-Celtic method of construction is also a shell-first technique, in that the hull shape is dictated by the shaping of the planks, not by the underlying framing of the finished hull.[5]: ch 4
There are precursors of clinker construction. The archaeological remains of a river boat dated to the first two centuries AD (described as Romano-Celtic), found in Pommeroeul in Belgium, had a singlestrake that overlapped the underlying plank – though it is not clear how it was fastened. Earlier finds have bevelled lap joints or other similar arrangements that do not have the full lap of clinker. These include theDover boat andFerriby 1 (both dating to the middle of the second millennium BC) and theHjortspring boat (c. 300-350 BC). In these cases, the planks are stitched or sewn together. The Hjortspring boat is built shell-first so suggesting some continuity with the Nordic tradition of clinker construction.[14]: 201, 207–210 [5]: 63-66
The earliest example of ship and boat building using overlapped planking joined with metal fastenings is in an extended logboat from Björke in Sweden. This dates toc. 310 AD. TheNydam boat (c. 320 AD) is an almost complete example of a boat built with clinker construction. It has overlapping planks joined with iron nails driven through the lap. The nails are clenched overroves on the inside of the planking. The boat was built shell-first.[5]: 63-66 [14]: 210-211
Though clinker construction is closely associated with Nordic countries, the same technique was used at an early stage in other parts of Northern Europe. The Saxon burial ship atSutton Hoo in eastern England is an early (c. 630 AD) example of this sort of ship occurring in the broader Northern European area. Other sites from the 7th century AD includeKvalsund, Norway, Gretstedbro inJutland andSnape in eastern England. One difference from the Nydam boat is that individual planks in the later period are shorter and narrower. This suggests that large oak trees for ship-building had become a lot less common by the 7th century, so timber of smaller dimensions had to be used.[5]: 65 [14]: 207-210
The 8th, 9th and 10th centuries saw the use of Vikinglongships for raiding and settlement. Archaeological remains of these clinker-built ships include theOseberg ship and theGokstad ship. These show some development from earlier vessels, including a partialkeelson which acted as the mast step. As well as these warship types, cargo vessels were built which were less extreme with greater beam and more emphasis on propulsion by sail, together with extra cross-beams to strengthen the hull for greater weight carrying.[14]: 212-217
Thecog is part of another ship-building tradition in Northern Europe that existed at the same time that the purely Nordic-tradition clinker vessels were being built. Though the classic cog construction uses flush planking for the bottom, the sides are constructed in a clinker method – with the difference that the nails that passed through overlapping planks were simply bent over and driven back into the plank, rather than using roves.[5]: 66
Clinker-built vessels were constructed as far South as theBasque country; theNewport Medieval Ship is an example of a clinker-built vessel that was built in the Basque region.[15][16] By the 14th century, clinker-built ships and the cog represented the major construction methods in Northern Europe.[5]: 66
Carvel construction was developed in the Mediterranean around the end of theClassical antiquity period.[d] By the end of the 13th century AD, Mediterranean ships were being built on a skeleton basis, with hull planks being fixed to the frames and not to each other. At the same time, Northern European cogs were voyaging into the Mediterranean. The two maritime technological traditions had differences beyond the hull construction methods. Mediterranean ships were carvel-built,lateen rigged (using more than one mast on larger vessels) and still used side rudders. The visiting cogs had a singlesquare-rigged mast, a stern-post mounted pintle-and-gudgeon rudder and clinker sides. As part of the process ofmerging these two sets of traditions, carvel-built ships started to arrive in Northern waters. They were soon followed by shipwrights with the skills to build in carvel construction, with the first being built in this region in the late 1430s. The change is still not well understood. The frames of carvel could be made stronger to support the weight of the guns that ships were starting to carry and allowed gun-ports to be cut in the hull. Carvel construction may have solved the shortage of large cleft oak planks from which to make larger clinker vessels.[5]: 50, 58-60, 69-72 Despite the large-scale move over to carvel construction for large vessels, clinker construction remained prominent throughout Northern Europe.
The Nordic clinker boat tradition was inscribed to theUNESCO List of the Intangible Cultural Heritage on December 14, 2021, as the first joint Nordic application to the list.[4]
![Clinker hull of the Nydam Boat from Jutland.[citation needed]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aNydamboat.2.jpg)
![Clinkered prow of the Viking Oseberg ship.[citation needed]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aExhibition_in_Viking_Ship_Museum%2c_Oslo_01.jpg)
![Clinker-built medieval cog from Stralsund.[citation needed]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aKogge_stralsund.jpg)
![Clinker-type lapped iron plating on the lower hull of the historic, record-setting SS Great Britain (launched 1845).[17][18][19]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aClinker_built_iron_plating%2c_SS_Great_Britain.jpg)
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