Material: Elm timber
Provenance: Antikythera shipwreck. From the material retrieved in 1976
Date: 220 B.C. (▒43)
Dimensions: L. 0.90 m., w. 0.26 m., th. 0.11 m.
Inv. no: Athens, Ephorate of Underwater Antiquities BE 2011/11
Room:Temporary Exhibitions Wing, Room I
It would have been positioned on the lower part of the ship's hull. The plank is made of elm timber (ulmus), known in the Aegean region as karagatsi. In traditional shipbuilding, from the existing five varieties of elm, two are primarily used, namely the ulmus montana and the ulmus pedunculata. In comparison to other timbers of the Mediterranean, it has an inferior mechanical strength though it does not split easily, it dries fast and most importantly it has long life duration. On the other hand, however, it is vulnerable to insects and fungi and has a tendency to warp. Although the use of elm timber was frequently preferred in water-logged environments, yet in ancient shipbuilding its employment was rather limited. Evidence which derives from some Roman shipwrecks suggests that elm would have been used primarily in the construction of the frames. There are traces of caulking on the outer part of the plank. A layer of resin or pitch would have been placed between the planking and a sheath of lead sheets, to protect the ship's hull against marine borers. The lead sheets were held in place by short bronze nails. On the surviving plank six horizontal, parallel lines of short bronze nails are fixed at a regular spacing of 0.04-0.05 m.: the same distance is kept between each individual line. Particular care is given to the vertical axial alignment of every nail as well: the nails in any one line correlate to the intermediate spacing of those immediately above and below - in the quincunx pattern. A consistency in the distribution of the nails is thus achieved most effectively, distributing the stresses evenly and regularly over the area concerned: an essential consideration given that the hull is exposed to heavy vibrations and external pressures.
On the outer surface of the plank, seven nails, with round heads of about 0.034 m. in diameter are visible. Their shafts, circular in section, are driven through wooden treenails, hammered into prefabricated holes that were themselves drilled through the planking and the frames. These nails fastened the planking to the frames. They were hammered in from the outside: two, and in some cases three, nails were required for each frame in each plank. Especial attention was paid to avoid placing two bordering nails on the same vertical axis: this care reduces the risk of splitting the attached frame. The considerable thickness of the plank allowed the cutting of mortises on the edges in two parallel lines. The broken tenons of the joinery are still visible in these cuttings. They have an elongated rectangular shape; their sides narrow towards both ends. Their maximum length was 0.22 m., while their width did not exceeed 0.08 m. After the planks were joined together, holes were drilled through them: the tenons were then held firm in position by being transfixed by wooden pegs. Both tenons and wooden pegs were made of oak (quercus). Although working oak is considered to be difficult, its timber possesses a high endurance and longevity and only a medium degree of contraction expansion. These are perfectly appropriate qualities for functional parts such as tenons and pegs.
The extremely hefty width of the planks, enabling the cutting of the mortises in two eccentric and off-parallel lines, and the close-set frames all suggest that the ship was heavily timbered, constructed for carrying an enormous load.
Bibliography: ═. ╩altsas - ┼. Vlachogianni - P. Bouyia(eds.), The Antikythera shipwreck. ďhe ship - the treasures - the mechanism, Catalogue of the archaeological exhibition, National Archaeological Museum, April 2012 - April 2013, Athens 2012, 40-41 no. 1 (G. Koutsouflakis).