1. Three ships in Wismar harbour

1The city of Wismar is located in the northwestern part of Mecklenburg Western Pomerania on the Baltic Sea. With its sheltered location at the end of a bay, Wismar served as a port from at least the early 13th century onwards (Radohs 2016) and was an early member of the Hanseatic League (fig. 1).

2In 2016, the planned extension of the modern seaport led to extensive construction work east of the existing commercial harbour. During the unexploded ordnance survey of the same year two medieval shipwrecks dating to the 13th century were discovered and subsequently excavated and recovered by an archaeological contractor. During the excavation of the second wreck (Wismar, Ostsee II, Fpl. 30), a third wreck was encountered in April 2017. This new site, designated Wismar, Ostsee II, Fpl. 32, was partially covered by the overlying wreck Fpl. 30. The excavation of the first two sites was completed in August 2017 and the third wreck was protected by an exclusion zone pending a decision about its future.

3In November 2018 the state authority for culture and monuments (Landesamt für Kultur und Denkmalpflege Mecklenburg-Vorpommern, LAKD) was tasked with the excavation and documentation of the site. For the construction work to ­continue, the wreck and all associated material had to be lifted from the seabed. The recovered timbers were to be documented on the surface and subsequently wet-stored until conservation treatment could be started.

2. Excavation and recording of the wreck Wismar, Ostsee II, Fpl. 32

4The excavation was carried out over a period of 26 days in November and December 2017. As the wreck was located in 2.5 m of water close to the shoreline, the dive team of six archaeologists was based on a shallow draught MPV with spud legs. All diving was conducted using surface air supply. A layer of compact silt up to 1.5 m thick covering parts of the wreck site was removed using water dredges. Once the wreck was fully exposed, the timbers were systematically removed following the reverse order of construction and lifted to the surface. Each stage of the excavation was documented using photogrammetry. As the visibility on site was limited, a GoPro Hero 5 camera with additional lighting system was used to obtain the necessary footage. The survey data for each layer was processed overnight with the goal of producing a basic site plan, which could be used to reference the timbers that were lifted to the surface (fig. 2). Upon recovery, the timbers were moved into a wet storage basin in the port of Wismar and finally to the LAKD conservation facilities in Schwerin.

5Following the excavation, the ship timbers were recorded in 3D using an Artec EVA structured light scanner. Each timber was cleaned, sampled and subsequently scanned. The resulting 3D models were imported into Rhinoceros3D, where they could be annotated. A written description and photographs of details were then added in order to compile the final catalogue entry for each timber (Auer, Ditta, 2019; Van Damme in this volume).

3. The “Big Ship” of Wismar

6The 19.8 m-long and 5.3 m-wide wreck was resting in the soft bottom sediment at a 20 to 25 degree angle to the port side, where 17 strakes of outer planking were preserved. On the starboard side only four strakes survived in situ. Neither keel nor posts were found. Inside the wreck, 28 frame stations were preserved with their associated timbers. Apart from the intact keelson, stringers and part of the deck construction aft could be recorded (fig. 3).

7The survival of garboard strakes, post wings forward and aft and the well-preserved aft scarf on the aftmost outer planks point to an intentional removal of keel and posts at the time the vessel was abandoned.

8The majority of the lapstrake outer planking was radially cleft from straight-grown oak trees. From the thirteenth strake upwards, a number of pine planks were used. Most notable are large carved pine planks in the fourteenth and fifteenth strake, which might have served as a longitudinal reinforcement and outer hull protection. The oak planks vary between 2.4 m and 6.8 m in length and have an average width of 30 cm in the midship area. The pine planks are generally longer and thicker than those of oak. Planks within a strake were connected with short (9 cm to 15 cm) vertical scarf joints, which were sealed with mats of sheep wool and tar. Adjoining strakes were sealed with strands of sheep, goat and cattle hair and wood tar and fastened to one another with round-shafted clinker nails with round heads, which were clenched over rectangular rove plates on the inside. Where clenching on the inside was not possible due to a lack of space, the clinker nails were inserted inside out. An interesting detail in the outer planking is the reversal of the scarf direction above the waterline. While scarfs in the lower part of the vessel were orien­ted with the opening facing aft to prevent water ingress, they faced forward from strake 14 upwards.

9The framing system with joggled floor timbers, bitis and biti knees is characteristic of the Nordic shipbuilding tradition from the late Viking Age and high medieval period. Towards the stern, in relation to the aft deck, the bitis and biti knees are combined in a single piece and the timber sequence continues with shelf clamps, beams and beam knees.

10The frame spacing is relatively regular with an average distance of 51 cm. The spacing between the second and third frame station and the twenty-second and twenty-third frame station from the bow is above average, with 86 cm and 87 cm, and defines the extension of the open hold.

11The floor timbers were boxed from oak crotches and follow the pronounced V-shape of the underwater hull. The arms have a rectangular section with a moulded dimension in the range of 9 cm to 11 cm and a sided dimension in the range of 10 cm to 12 cm. The timbers were not secured to keel or garboard strakes. The floor timber at the first frame station has a rounded tip on the inboard surface, giving it a characteristic W-shape. Similar frames are known from other ship finds (Englert 2015, p. 163). In the case of the Danish find Lynæs 1 (1140 AD), the W-shaped floor timber is believed to mark the end of the keel or hold (Englert 2015, p. 164).

12The majority of the preserved bitis were boxed from straight-grown pine, whereas the biti knees are made of compassed oak. The timbers are rectangular in section with a moulded dimension in the range of 13.5 cm to 18 cm, and a sided dimension in the range of 8.5 cm to 12 cm. On the underside, the preserved bitis are furnished with two elegant arches, besides the joggles for receiving up to five strakes. The first arch is used to lodge the floor timber into the biti, while the second arch probably has a decorative function or was used for weight reduction. Along the centreline of the vessel, the bitis were notched to fit over the oak keelson. The bitis at the eleventh and twelfth frame station were cut out to receive the foot of the mast and thus served as an extension of the mast step.

13Both in the floor timbers and bitis, small triangular notches at the end of each joggle functioned as limber holes.

14The frames and other internal timbers are fastened to the strakes with pine treenails of 30 mm diameter. The treenails have protruding dome-shaped heads and were expanded with large irregular pine wedges on the inboard side.

15Four types of internal longitudinal strengthening timbers or stringers are found across the hull. The lowest stringers are a set of short pine blocks positioned on the fourth strake on both sides of the vessel fore and aft of the keelson. These lowest stringers served as continuations of the keelson, but allowed access to the top of the keel, presumably for the placement of a bilge pump. Partially preserved on the port side, an oak stringer was placed on the eighth strake and for the entire length of the keelson. A third oak stringer was placed on the sixteenth strake, above the height of the aft deck, and likely extended across the entire length of the vessel. This stringer is also partly preserved on the port side. The fourth type of stringer is also made of oak and is partially preserved on the port side. This so-called inwale runs on the inner upper edge of the seventeenth strake, which is the last strake of the vessel.

16The deck construction of the vessel can be traced on the port side aft (fig. 4). Here, a preserved beam shelf and a number of oak knees provided the substructure for a half-deck. The beam shelf is made of pine and stretched from the end of the keelson up to the twenty-eighth frame station, clearly defining the extension of the deck. The fore end was fastened starting at the thirteenth strake, while the aft end was fastened at the eleventh strake.

17A massive knee in lime wood (Tilia sp.) at the twenty-sixth frame station served as a bearing for the windlass. While this type of windlass bearing finds a comparison in the much smaller Elling Å ship dated AD 1163 (Bill 1997), a corresponding windlass for this type of arrangement was found in connection with the “Big Ship of Bergen” dated AD 1187/88 (Christensen 1985, p. 180).

18A 22 × 22 cm rectangular opening in the sixteenth strake at the height of the twenty-second frame station suggests the presence of a through beam. This is also confirmed by a recess in the underside of the third stringer, which would have been notched on the beam.

19Through beams are known from the Bryggen excavations (Christensen 1985, p. 66) and at least two of these beams could be linked to the find context of the “Big Ship of Bergen”. The largest beam found in Bergen had a square section of 20 × 20 cm. Also, the much smaller Kalmar 1 wreck from the first half of the 13th century had through beams (Åkerlund 1951, p. 32).

20Another interesting feature is a smaller opening measuring 10 × 16 cm above the third stringer and just aft of the through beam. The position above the deck and behind the end of the keelson suggests that this might be a scupper hole. A similar solution can be found in the Kalmar V wreck, a small merchant ship from the early 16th century. Here, a hollowed-out beam at the aft end of the keelson above the deck led the bilge water to a round scupper hole in the ship’s side. The gutter beam was associated with a primitive bilge pump (Åkerlund 1951, p. 74).

21Most probably the Wismar ship was also equipped with a similar pump arrangement. The position of the lowest two stringers in continuation of the keelson allows free access to the lowest point in the ship between the twenty-second and twenty­third frame stations.

22The oak trees used for the construction of the vessel were felled in the period AD 1184-90 in the area of the Swedish west coast (Daly 2018). Based on the fact that neither the analysis of the construction timbers, nor the dendrochronological data produced any evidence for repairs, and that the outer planking was in a very good overall state, it is likely that the ship was only used for a short period of time. The artefacts found in the sediment above the wreck date to the early 13th century and suggest that the ship was wrecked or abandoned in the first part of the 13th century.

4. The “Big Ship” of Wismar in context

23Based on the archaeological evidence, the “Big Ship” of Wismar was a sizeable cargo vessel of about 26 m length, which was built in the Nordic clinker tradition. Although a full reconstruction is pending, the beam can be estimated as 8 m. The vessel was remarkably symmetrical in its construction. It was probably double ended and had a single mast. An open hold stretched over the whole length of the keelson. A series of beams and through beams just forward of the mast provided stability. While the bow section is not preserved, a 3.5 m long half-deck could be reconstructed aft. The deck space was used to operate the large windlass, which stretched from one side of the vessel to the other, as well as the bilge pump, which was located aft of the keelson. The preserved structure indicates the existence of another, higher deck further aft, which might have been the position of the helmsman. Altogether, the “Big Ship” of Wismar can be characterised as a large, well-built, seagoing merchant vessel, which was ­constructed in the Nordic clinker tradition. While many features recall the Scandinavian ship finds from earlier periods, the vessel shows some modern traits, such as the use of through beams and the existence of a bilge pump.

24In general, the preserved material shows strong analogies between the Wismar ship and the Danish wreck Lynæs 1. The similarities range from general layout and frame spacing to the presence of rubbing strakes and W-shaped floor timbers. Another common element between the two ship finds is close correspondence in the origin of the oak timbers. Differences include the regular use of pine wood for long and straight elements in the Wismar ship and the lack of evidence for mast bitis or through beams in Lynæs 1. However, considering the age difference of 40 to 50 years between the two ship finds, these features could also be a later phenomenon. The “Big Ship of Bergen” and the Karschau wreck (AD 1145) can also be added to this comparative group. In the Karschau wreck (Englert 2015, p. 191) both the mast bitis and the W-shaped floor timbers were present. The wreck, however, was not suffi­ciently preserved to provide evidence of rubbing strakes or through beams. The Bergen find, on the other hand, not only dates to the same period as the Wismar ship, but the preserved elements also indicate strong similarities in the construction. The “Big Ship of Bergen” was, however, a larger version of the Wismar ship and all preserved timbers are made of pine.

5. Conclusion

25To conclude, the Wismar wreck fits perfectly into the compara­tive study presented by A. Englert (2015) on large ­clinker-built ships of the Middle Ages in Danish waters. Englert describes the very similar Lynæs 1 ship as a “sophisticated tool of a long­distance trade operated by professional merchants” (Englert 2015, p. 189) and interprets the ships in his study as indicators of professional trade. The “Big Ship” of Wismar can also be seen in this context. Construction and use of the vessel fall into the reign of the Danish kings Knut VI and Valdemar II, during which the area around Wismar formed part of the Danish kingdom.

26The Wismar wreck thus adds to our knowledge of Scandinavian shipbuilding in the late 12th century. While the documentation of the recovered material and the primary analysis of the ship construction have been completed, the timbers of the Wismar find are currently awaiting conservation in Schwerin. Further planned steps in the investigation include a full comparative analysis of the wreck find and a digital reconstruction of the ship.