In the Northern Seas we may take as our starting point ships of the type probably used by the Anglo-Saxons in their invasions of the British Isles from the early fifth century.1 The double-ended, long oak ship excavated at Nydam Moss on the island of Als in the Baltic Sea, southern Denmark, is dated to c.310–20 ce. It was originally around 25 m long, 4.3 m in the beam amidships, around 1.35 m deep in the hull amidships, rising to around 2.25 m at the bow and stern. It was an open rowing boat, clinker built, hull first, with only a bottom plank and five strakes per side. The strakes, which were single planks carved from whole trees, were fastened to each other with iron nails clenched through square iron washers. Cleats were left on the inside of the carved strakes roughly every 1.25 m and ribs cut from naturally curved branches were lashed to them later. Fifteen thole pins for oars were lashed to the top strakes or gunwales on either side. A large quarter rudder was found at one end. There is no evidence that the ship carried a mast or sail, and it appears to have been purely a rowing boat.