Nagels en plaatjes uit Wijnaldum (Fr.) Aanwijzingen voor Friese klinkerschepen in de vroege Middeleeuwen?
Iron roves and rivets from the excavations of the terp (dwelling mound) Tjitsma near Wijnaldum (Westergo, Friesland) indicate that the Frisians of the 5th–9th centuries may have used clinker-built boats and ships for their overseas contacts. Until now vessels of the Utrecht type (10th–11th centuries) were considered also to be the vessels of the early medieval Frisians. Gold, silver and iron working is attested at Tjitsma, but evidence for shipbuilding in clinker technique was lacking until now. However, the distribution of roves and rivets over Scandinavia and England, and now also the northern part of the Netherlands, makes the use of clinker-built ships by the Frisians in the 5th–9th centuries AD plausible.