Reconstruction of The Yenikapi 12 Medival Ship

The Yenikapı 12 (YK 12) shipwreck was uncovered in 2007 in the course of salvage excavations at the Theodosian Harbor; one of the most important Byzantine harbors on the Marmara coast (Fig. 1). Documentation work on the wreck was carried out in two main phases: in situ documentation occurred without disturbing the integrity of the hull, and documentation of each piece separately was done in İstanbul University’s Yenikapı Shipwrecks Research Center. 

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Fig. 1 YK 12 shipwreck (In situ).

Through measurements taken without moving the wooden members of YK 12, documentation towards establishing the volume of the hull, the curves of the frames, the angles of the keel, the stem and the sternpost, and the relationship among the members was completed in order to grasp the entirety of the vessel.  To this end, a team of experts recorded the mass of the body of YK 12 in 3D with the help of a Total-Station, made photo-mosaics, and executed measurements, illustrations, visual evaluation and photography work hand in hand (Fig. 2, 3, 4). Following the documentation work, members of the wreck were moved dismantled, lifted on molds prepared to salt removal pools and passive conservation methods were applied. Following this step, all wooden members of the vessel were documented with the help of a Faro-Arm digitizer device and recorded in 3D in the digital environment (Fig. 5)

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Fig.2  Total station measurements of Yenikapı 12 (left).

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Fig.3 In situ drawings of planks (right).

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Fig.4 Photo Mosaic image of YK12.

Detailed analyses of the wood finds resulted in significant information, such as the standard units used in the vessel’s construction, the marks of the shipwright, the tools he used, and what part of a tree was used for the wooden members (Fig. 6). As a result of three years of evaluations, the dimensions of YK 12, its design principles, structure, and construction sequence were identified and hypotheses developed about the locations and shapes of its missing parts. These data facilitated reconstruction drawings of the vessel, which were then fleshed out, and illustrations and animations of the vessel on the sea and in the harbor have been prepared.

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Fig.5 Digital drawings of ship members by Faro-Arm device (left).

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Fig.6 Consultation of shipbuilding technique (right).

Reconstruction

A 7-meter-long and 2.3-meter-wide portion of the hull has survived. Because the boat sank at a slight angle on its hull and was suddenly covered by sand, part of the amphorae cargo, and therefore most of the wooden members under this cargo, were preserved completely and in situ. Its keel, stem and sternpost, eight planking strakes on the port side and nine planking strakes on the starboard side, two wales on the starboard side, part of the bulwark, 25 floor timbers, 15 futtocks, the complete mast step, and 43 ceiling timbers have survived (Fig. 7).

 

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Fig.7 Plan drawing of YK12.

 

In addition to the exhustive research results of the hull members, the presence in the Yenikapı excavation area of several other wrecks very similar in terms of size, form and construction, have increased the precision of our reconstruction work. Accordingly, we have shaped a hypothetical form by adding reconstructed elements on to the original parts of the hull of YK12, 60 per cent of which have been preserved.  At this stage of the study, first of all it has been investigated that how the available information with a high degree of accuracy can be enriched in the first place. Considering the necessary symmetrical arrangement of both sides of the ship, the hull lines of the starboard side were applied to the port side through plan and section drawings. A 1:10 scale research model and a 1:10 scale model of the hull remains (in situ model) were made for facilitating three dimensional observations and providing more accurate reconstruction work (Fig. 8).

Missing parts of the YK12 hull, symmetrical completions, frame pattern, hull planking lines, angle definitions, proportional increase and the upper structure were determined on the basis of various clues such as nail holes, through beam slots and bulkhead arrangement at the stern. According to the reconstruction results, YK 12 was a small trading vessel approximately 9.20 m long and 2.54 m wide, suitable for coastal navigation. It traveled with a single-mast lateen sail and was controlled by two quarter-rudders characteristic of that period. It had a special compartment closer to the stem, a foredeck, side-deck, and a poop deck. The hold was open on top and probably closed with a tarp to prevent sea water from splashing into the vessel. The bow and the middle parts where the hold was located, as well as the flat frames and curved hull, were built wider than the stern a design that increased loading capacity. It carried 180-250 amphorae in its hold, which were 80 cm high and 3.20 m long on the average. Moreover, the flat-framed hull shape increased the boat’s ability to enter easily into shallow harbors and bays, and the wider form of the bow increased its capability to cope with high waves.

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Fig.8 Laser scanning of 1:10 scale model of the hull remains.

Following the reconstruction studies, drawing of hull lines and sections, preparations have been made for the full scale reconstruction of YK 12. The reconstruction is being built at RMK Marine shipyard in İstanbul; one of the pioneer companies of Turkish shipbuilding industry. Construction team includes İstanbul University’s Conservation of Marine Archaeological Objects Department staff, experienced carpenters, ship designers and experts. The design of the hull form of the reconstruction is based on the actual remains of the shipwreck. A complete set of hull lines was generated by a combination of total-station measurements, digitizer and hull line drawings, and scaled model-building. Missing information about the ship was gleaned from both iconography of the period and reconstructions of contemporary shipwrecks. Reconstruction data was processed with digital software providing hydrostatic values, stability curve, load distribution, load center calculations and volumetric analysis.  Other data such as planking dimensions, planking and frame joint locations, framing pattern, ceiling pattern, bulkhead arrangement, through beam locations and deck height were defined in detail.

 

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Fig.9 Slicing the chestnut trunks.

In the reconstruction building, chestnut trunks 4.5 m in length and 50 cm in diameter on the average and oak timber in dimensions of 10x40x400 cm were used. The construction was made according to the original hull shape, dimensions and tree species (as far as possible). The construction began with setting up the keel. Keel pieces sawn according to the moulds were joined through hook scarves, also supported with wedges and stretched with a central cord in order to prevent instability (Fig. 10). Frame-plank joint locations, keel, plank and floor-futtock joint forms, planking pattern was built according to the original ship (Fig. 11, 12). 

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Fig.10 Setting up the keel (above).

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Fig.11 S scarf and nail holes on a plank (below left).

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Fig.12 Hook scarf on keel (below right).

After the completion of the planking strakes, wales and frames, inner construction elements such as through beams, bulkhead, mast step and the ceiling strakes were installed (Fig. 13). The rigging and sailing canvas were provided by the support of sailing experts (Fig. 14).  

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Fig. 13 Construction of reconstruction.

It is important to note that although the material and design of the reconstruction is based on the actual remains of YK 12 shipwreck, this study should not be considered as an experimental archaeology project. Rather it aims to perceive a 9th AD century ship with its original form and dimensions as a physical visual source.  Future exhibitions at both national and international museums and sailing experiences have been planned.

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Fig. 14 Testing of sailing mechanism.

 

 

Dr. Işıl Özsait-Kocabaş-Istanbul University