Archaeologists investigating an old cellar in Konstanz, a city in southern Germany on the shore of Lake Constance, discovered that its roof was built from the timbers of a medieval ship. The cellar dates to 1244 AD.
The roof, covering about 25 square meters, was made from wood taken from a vessel. Researchers identified 19 planks thanks to features such as wooden pegs, rows of nails and the shape of the individual pieces.
Aline Kottmann, a specialist in medieval archaeology at the State Office for the Preservation of Monuments (Landesamt für Denkmalpflege), said in a statement that at first it was only clear the planks had been reused, and that discovering they had originally formed part of a ship was a complete surprise.
A common medieval practice, on an unusual scale
Reusing retired ships as building timber was a known practice in the Middle Ages. What makes this case exceptional is the amount of material that survived. Alexandra Ulisch, a member of the state project 'Wrecks and Deep Sea', said the Konstanz find was truly exceptional because it did not consist of isolated fragments but of the hull of a nearly completely intact ship.
Researchers believe the vessel was probably a flat-bottomed cargo ship, a type commonly used in the Lake Constance region, which straddles the border between Germany, Switzerland and Austria.
Wood preserves details of medieval shipbuilding
Some of the planks show repairs made while the ship was still in use. Four such repairs have been located so far, including one dovetail-shaped piece that has no known direct equivalent in the medieval shipbuilding tradition of the region.
The timbers also retain part of the material once used to seal the joints between pieces. According to Ulisch, the planks were cut to fit precisely and remain on the roof in the same arrangement they had when they were part of the ship.
Next steps for researchers
Researchers now plan to carry out dendrochronological analysis of the wood, a technique that dates timber by examining its tree rings, and to study the caulking material used to seal the hull.
Kottmann said the remains offer an advantage over shipwrecks that stay underwater, because they have been preserved in a far more accessible environment. Because of this, the find could become a valuable source of information on medieval shipbuilding techniques used on Lake Constance.
