Construction of the Gokstad Ship

The original Gokstad ship was built around 890 AD, as determined by dendrochronological (tree-ring) dating of its timbers. It measures 23.80 meters in length with a beam of 5.10 meters and was constructed almost entirely of oak, the most prized shipbuilding material in the Viking world. Understanding how the original was built is central to the challenge of replicating it faithfully.

Clinker Construction: The Viking Method

Viking ships were built using the clinker (lapstrake) method, in which longitudinal hull planks, called strakes, overlap each other at the edges and are fastened together with iron rivets. The Gokstad ship has 16 strakes per side. Each rivet was driven through the overlapping planks from the outside, and inside the hull, the protruding end was hammered over a rectangular iron washer called a rove.

What makes clinker construction distinctive is that Viking shipwrights built the hull “shell-first.” The strakes were attached to the keel and to each other before the internal frames were added, the opposite of the frame-first approach used in later European traditions. This produced a hull that was both strong and remarkably flexible.

Wood Selection and Preparation

The shipwright’s knowledge of timber selection was critical. Oak was reserved for the hull planks, keel, and ribs due to its immense strength and resistance to rot. Pine was used for the mast, decking, and some internal components. Ash, elm, and lime were used for various fittings.

Nearly all planks on Viking ships were made from “radially split” wood, a technique virtually unknown in modern boatbuilding. Rather than sawing planks from a log, the shipwright split the trunk using an axe and wedges, following the natural grain of the tree. The result was planks that were stronger than sawn timber because the wood grain ran continuously through them. Individual strakes could be as thin as 2.5 centimeters while remaining both strong and supple.

The Keel: Backbone of the Ship

The keel was carved from a single, straight piece of mature oak, the longest and straightest available. It featured a T-shaped cross section that served not just for stability but acted as a spine, allowing the hull to flex vertically to ride over wave crests rather than crashing through them. The Gokstad ship’s keel measures approximately 16 meters.

Key Specifications

• Overall length: 23.80 m (78.1 ft)
• Beam: 5.10 m (16.7 ft)
• Strakes: 16 per side, clinker-built
• Oar positions: 16 per side (32 oars total)
• Sail area: Approximately 110 square meters, square configuration
• Rudder: Side-mounted on the starboard quarter, 3.3 m long
• Shields: 64 round shields, alternately painted yellow and black
• Estimated speed: Over 12 knots; replicas have achieved 10-11 knots

Hull Flexibility: Engineering by Design

One of the most remarkable features of the Gokstad ship’s construction is its deliberate flexibility. The bottom of the hull could rise and fall up to 18 millimeters in heavy seas, and the gunwale could twist up to 15 centimeters. This was not a flaw but a carefully engineered feature. The internal frames were fastened to the hull with wooden pegs (treenails) rather than rigidly, allowing the entire structure to flex with ocean swells. This flexibility was key to the ship’s ocean-going capability.

Caulking and Waterproofing

Between the overlapping strakes, the shipwrights applied caulking made from animal hair, typically from sheep or cows, proofed with tar. This was laid onto the lower inner edge of each strake during construction, creating waterproof seams throughout the hull.

The Sail

The Gokstad ship carried a square sail made from densely woven wool cloth known as wadmal, treated with animal fat for waterproofing. Remnants found in the burial showed the sail was sewn with red stripes. Producing enough wool for a single Viking sail required enormous labor, making it one of the most valuable components of the vessel. The sail hung from a horizontal yard attached to a mast estimated at 10-13 meters in height.

Tools of the Shipwright

Viking shipwrights worked with a surprisingly refined toolkit: broad axes for felling and rough-shaping, adzes for hollowing and contouring planks, drawknives for fine shaping, spoon augers for drilling rivet holes, and planes for smoothing. Wedges were essential for the radial splitting of timber. Chisels, hammers, mallets, gouges, and knives completed the set. Remarkably, no written plans existed. The shipwright, known in Old Norse as skipasmidr, worked from tradition, experience, and eye, passing knowledge through generations.

From History to the Horizon

These are the same methods and materials being used today at the Viking Ship Museum boatyard in Denmark to build the Vinlandferth replica. Every strake is split from oak, every rivet forged from iron, every seam caulked with tarred animal hair, just as it was done in the 9th century. To learn more about this effort and how you can be part of it, visit our Donate page or join the crew.