New insights into an iron age boat: Dating and materials analysis

Jim Crocker
11th December, 2025

New insights into an iron age boat: Dating and materials analysis

The Hjortspring boat as currently displayed at the National Museum of Denmark.

Image adapted from: Fauvelle et al. (Photo by Boel Bengtsson) / CC BY (Source)

Key Findings

  • Discovered in Denmark, the Hjortspring boat dates to the 4th or 3rd century BCE, confirming its use during the Pre-Roman Iron Age
  • Analysis of caulking material revealed a mixture of pine pitch and animal fat, suggesting the boat originated from a region with abundant pine forests, likely the Baltic Sea area
  • A partial human fingerprint was found on a caulking fragment, providing a rare, direct physical connection to the ancient seafarers who built and used the boat
The Hjortspring boat, discovered in Denmark, is the most complete prehistoric sewn-plank boat found in Scandinavia. Understanding its construction and origin provides crucial insights into the maritime capabilities of early Northern European seafarers. For decades, archaeologists have relied on the boat’s structure and associated artifacts to infer its age, building techniques, and the people who sailed it. However, direct dating and detailed material analysis have been limited.[1] Lund University, alongside researchers from University of Gothenburg, Independent Researcher, Ringkøbing Fjord Museer, National Museum of Denmark and Israel Antiquities Authority, have recently published a study detailing new analyses of the boat’s cordage and caulking materials, significantly refining our knowledge of this important vessel. The core of the investigation focused on establishing a more precise timeline for the boat’s construction. Previous estimates were based on associated finds, lacking direct dating of the boat itself. The researchers employed carbon dating on lime bast cordage recovered from the original excavation. This yielded a date range of 381 to 161 BCE, placing the boat’s creation firmly within the first millennium BCE. This dating is significant as it provides a concrete anchor point for understanding the development of seafaring technology in the region. Beyond dating, the study examined the materials used in the boat’s construction. Caulking, the material used to seal the gaps between planks, was analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). This technique identifies the chemical components of a substance. The GC-MS analysis revealed a mixture of animal fat and pine pitch. Pine pitch is a resin derived from pine trees, and its presence is key to understanding the boat’s origin. The discovery of pine pitch is particularly noteworthy. The Jutland peninsula, where the Hjortspring boat was found, has limited pine forests. The presence of pine pitch suggests the boat, and likely its builders, originated from a region with more abundant pine resources. Based on the geographical distribution of pine forests in Northern Europe during the first millennium BCE, the researchers propose the Baltic Sea region, specifically east of Rügen and Scania, as a likely source. This finding builds upon earlier research exploring the navigational capabilities of Bronze Age seafarers[2]. That study used simulations to assess the feasibility of both coastal and open-water voyages between Jutland and Norway. It suggested that direct open-sea voyages of up to 110km were plausible, requiring boats capable of handling moderate waves and winds. The new dating from places the Hjortspring boat within a timeframe consistent with the capabilities demonstrated in those simulations, suggesting the boat was likely used for similar voyages. Furthermore, the earlier research highlighted the advantage of sails for long-distance travel[2], and the robustness of a boat capable of withstanding open sea conditions would have been essential for such journeys. The study didn’t stop at material analysis. Researchers also examined intact cordage fragments and imprints left on the caulking material. This allowed them to reconstruct the sewing and rope-making techniques used in the boat’s construction. The analysis revealed sophisticated methods for lashing the planks together, demonstrating a high level of skill and knowledge in boat building. Perhaps the most remarkable finding was the discovery of a partial human fingerprint on a fragment of caulking material. This fingerprint represents a direct physical connection to the ancient seafarer who worked on the boat. It is an exceptionally rare find, offering a tangible link to the individuals who built and sailed Scandinavia’s first plank boats. The fingerprint underscores the human element of this archaeological discovery.

Plant Science

References

Main Study

1) New investigations of the Hjortspring boat: Dating and analysis of the cordage and caulking materials used in a pre-Roman iron age plank boat

Published 10th December, 2025

https://doi.org/10.1371/journal.pone.0336965

Related Studies

2) Seafaring and navigation in the Nordic Bronze Age: The application of an ocean voyage tool and boat performance data for comparing direct open water crossings with sheltered coastal routes.

https://doi.org/10.1371/journal.pone.0320791


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