An investigation of a 13th century cellar in Constance on the German side of the border with Switzlerand has discovered sections of a ship used to construct the ceiling. The find gives archaeologists a unique opportunity to examine medieval shipbuilding techniques in a fully accessible environment instead of having to explore the few wrecks from this period under the waters of Lake Constance.

The cellar dates to 1244, a time when ships that were no longer in navigation were recycled, their planks reused as timbers for building projects on land. Timber planks in general were often recycled from earlier construction, so while the team from the State Office for the Preservation of Historical Monuments (LAD) in the Stuttgart Regional Council immediately recognized them as reused materials, it was only upon closer examination that their maritime origin was identified.

Since the State Archaeology Office (LAD) is currently searching for shipwrecks in Lake Constance as part of the “Wrecks and Deep Sea” project, it is well-positioned in the field of maritime archaeology. “It is known that decommissioned ships were reused as building timber in the Middle Ages. Nevertheless, the find in Constance is something very special: Here, not just individual fragments, but an almost completely intact ship’s hull was used,” reports Alexandra Ulisch, a staff member in the “Wrecks and Deep Sea” project. The ceiling spans an area of ​​more than 25 square meters and consists of at least 19 planks, which could be identified as parts of a medieval ship by characteristic wooden pegs, rows of pegs, and typical plank shapes.

The planks came from a flat-bottomed sailing vessel of a type that was common on Lake Constance in the Middle Ages. LAD archaeologists spotted repairs to the planks from when they were part of the ship’s hull, expertly fitted and cut patches where a damaged section had to be removed. At least four such repairs are present, and one of them, a dovetail inlay, has no comparable example known in the area’s medieval shipwrecks.

Another special feature is the visible connection between some planks: “They are precisely cut to fit one another and, just as they were installed in the ship, are attached to the ceiling. As a result, the caulking, the sealant between the planks, has also been preserved in some places,” reports Ulisch. This sealant is of particular interest to maritime archaeology and was therefore also analyzed.

The ceiling/hull has been scanned in 3D using “structure-from-motion” (SfM) technology which stitches together hundreds of high-resolution photographs to create a composite. Samples have been taken for dendrochronological analysis to narrow down the date the timbers were harvested.