the Oseberg ship

Right from the beginning we have been conscious of the fact that we are not just building a copy of the Oseberg ship. Our goal has been to build an exact replica that is accurate down to the smallest detail, while also gaining new knowledge and competence about how the original was built.

By Thomas Finderup

Since the Oseberg ship is almost 100% preserved it gives us a unique opportunity to learn more about the Vikings’ knowledge of handicrafts, of materials, construction methods and tools.

The Oseberg find was published in a magnificent four-volume series last century, and the original ship is exhibited at the Viking Ship Museum in Oslo. Nevertheless, the craftsmen have numerous questions that must be answered in order to build an exact replica of the ship, a reconstruction that in every way must resemble the original in terms of design, construction, materials, tool traces, details and the ship’s expression.

When studying the ship this closely we almost feel we are meeting the craftsmen who built the ship almost 1 200 years ago. Especially when we discover the small, inevitable mistakes and irregularities. It’s almost as if you can hear the boat builders cursing.

This intimate study helps us answer questions such as: how many builders were working on the ship? Were they in a hurry? How many different types of tools were they using?

The Viking Ship Museum

Our primary condition for reaching this ambitious target was free access to the original ship. The Museum of Cultural History and the Viking Ship Museum have always been very welcoming and provided us with all kinds of help.

We started off with close cooperation on reconstructing the ship’s form. Later, we were given access to the ship itself and the storage areas containing the original parts that had not been mounted on the ship due to their poor condition. These have been measured, drafted and later meticulously reconstructed. We have made innumerable visits to the original Oseberg ship (see fig. 1 and 2). All boat builders have taken part in photographing and measuring the ship.

It’s been vital that people involved in building the ship have had access to the original and achieved good “contact” with it and learnt what creates the overall impression of the ship. We focused especially on consistent construction details – or a lack of constancy – tool traces, accurate joints, details and so on.

The materials

The advanced design of the Oseberg ship shows that this has been the result of many hundred years of experience and tradition. A more accurate calculation method than experience and tradition has not yet been developed.

When you try to calculate the size of the Oseberg ship you require far bigger dimensions of timber. It’s only as a result of hundreds of years of experience that this light and very flexible construction has been developed; a ship that doesn’t need to fight the forces of the sea, but rather leans sideways and dances her way through the waves. A Viking ship could well say the same as the boxer Muhammed Ali: “I dance like a butterfly and sting like a bee.”

When we are building a reconstruction we don’t know which details are most important for the ship to withstand nature’s immense forces. Even the Vikings didn’t dare make any significant changes to the construction; they kept to their traditions to be on safe ground.

We have therefore emphasized studying the Viking choice of materials. It started when we investigated the ship’s stems and keel. They were studied meter by meter. The research included placement in the tree’s trunk, direction of the fibers, knots and growth speed.

Based on these results we were able to make a sketch of how the trees must have looked when they were still in the forest.

The keel

The original keel was measured and described meter by meter before we went hunting for the perfect tree in the forest. The almost 15 meter long original keel seemed satisfactory according to our norms for materials, but not much more than that. It has a number of knots, and the pith is somewhat unclear at the forward stem cleft (fig 3).

Despite not needing very high quality timber for the keel, it did take some finding. The fact that it needed to be 15 meters long was quite a challenge. Oaks rarely have a 15 meter long stem without large branches (fig. 4). On the original keel we note that the first larger branches crop out after eight meters.

After searching far and wide in both Denmark and Norway, a Norwegian oak from the Jarlsberg Manor, close to the building site, was donated to the project.

The next thing we had to consider was how to cleave the keel free from the log. It was important to bear in mind the iron seams that would be knocked into the keel across the mirror. If you don’t do this properly there is a risk that the keel may crack up between the seams. The point is to position the keel so that the pith is slightly under the middle of the keel’s section (fig. 5). By doing this the oak tree’s pith rays will be parallel to the surface of the T-shaped keel. It seems the Vikings attempted such a positioning in the original ship, but didn’t quite make it on the last meters at the front of the vessel.

We experienced some of the same difficulties at this point since the keel needed to be bent upwards to meet the rounded shape on the stem. We recognize that the design has been very important to the Vikings and other requirements were set aside. (Fig. 6)

The stems

The stems of the Oseberg ship were not entirely preserved. The lower part of the aft stem is completely preserved and part of the upper.

Only a piece of the front stem was preserved. We don’t know how large it has been. We can only state that it must have been longer that the preserved piece as there are no signs of any joints (fig. 7).

Neither of the stem elements was ideal for their purpose. The direction of the fibers do not follow the curve of the stem (fig. 8). Then again: the Vikings probably felt that they were good enough.

Their demand for design made it necessary to press the materials to the utmost. Our drawings, photos and measurements show us that the Vikings probably used huge oak trees with a large side branch at the correct angle (fig.9).

It has proved extremely challenging for us to find the perfect trees. There was always something not quite right. If the branches were at the correct angles from the trunk, then there was often a rotten branch or the side branches were too big.

However, after many days of wandering and searching in the Zealand woods and with great help from forest warden Hans Kolling Andersen we finally succeeded in finding four potential trunks. Only two of the trunks satisfied demands for size and quality.

The material for the aft stem is very similar to the original. In the instance of the front stem, however, the original was of such poor quality regarding the direction of the fiber, that it was not justifiable to copy it. (fig. 3). This is why the front stem has been made from a trunk with almost perfect fiber conditions (fig. 10).

The planks

The Oseberg ship has a design that pushes wood as a material to its utmost limits (fig. 10). The planks for the ship have been fashioned out of straight trunks. The widest planks are 40 cm wide, requiring a trunk with a diameter of about 120 cm at chest height (fig. 11). The bottom part of the tree weighs all of 10 tonnes.

In addition to the fact that the trees have to be huge they must also be straight and free from branches for the first eight meters, preferable be completely round without any interior rot or twisted fibers.

If the trunks do not satisfy these requirements then the results after splitting will at best be planks of inferior quality – and at worst quite useless. Twisted growth is especially damaging. (Fig. 13)

When a trunk fulfills all the above requirements, it can be chopped into 16 large cake-shaped chunks, sometimes 32 pieces, before forming the ships planks can begin. (Fig. 14 and 15).

If the trunk does not meet all these requirements there may perhaps only be 8 pieces good enough to become planks and thus huge waste. As far as we know, there are no sources available that tell us anything about this cleaving method. The Vikings with their hundreds of years of experience were probably much smarter than us.

Perhaps this method is in use in other parts of the world? We are constantly improving our methods to achieve a higher degree of utilization (fig. 16). Still, it seems difficult to set out precise rules for how this is to be done. No trunks are alike, so the method must be adapted to each single trunk. The final dimensioning of the planks is based on hundreds of measurements made of the original ship.

The ribs

The ribs require large oak trunks that have long and similar branches at exactly the correct angle and without side branches (fig. 17). As the ribs of the Oseberg ship are made of long branches that reach all the way up to the meginhufr (the 10th strake – fig. 18 and 19) on both sides, it’s understandable that it’s extremely difficult to find such trees.

During the process of sourcing timber questions constantly came up, such as: how did they transport trees to the building site? Did they chop the planks in the forest? How were they able to cut down the trees without damaging the branches and so on.

The technical issues

The next questions that came up during the building process were of a more technical nature:

The first was: How did they gather the stems? It seemed quite logical. They were assembled with a diagonal splice as on the drawing. Closer examination of the original revealed that this splice was used, and a very special one at that. The surfaces are not straight, but twisted and S-shaped. (Fig. 20).

This seems incredibly difficult for a present-day craftsman to do. A joint like this can’t be made using a saw and plane, but rather an axe. A joint made in this manner becomes much stronger and more beautiful. This is a good example of how the tools control the design and technical solutions.

When we first recognized this detail at the stem we decided to control the joints between the aft stem and forming a gliding transition between stem and keel.) As we thought, the drawings were both wrong and simplified. These clefts were also S-shaped, seen from above (fig. 21).

The cleft in the front part of the ship was not preserved, as we mentioned (fig. 20). However, when we examined the original to find if anything was left of the cleft, we made a new discovery.

The wonderful old photos from the excavation showed that there was nothing left of the joint. Therefore we decided to investigate how the stem was gathered on board the ship as it stands at the Viking Ship museum today. It appeared to be a combination of old and new materials. A new joint had been chopped from the old stem to join it with the new top (fig. 22). We examined how much had been chopped off the original piece and decided it was about 7 cm. Then we made another discovery. The wood carving on the part that had been chopped off had not been correctly copied on the new part of the stem. Somebody had created something new.

On our stem we have corrected this mistake and executed the woodcarving as it was on the original.

Traces of tool use

Studying the traces of tools used is an important factor when creating a reconstruction with the same expression as the original.

We have focused on this from day 1. We had actually worked on this aspect for years before we started building. At that time the floorboards had been removed from the ship. This is where you find some of the clearest traces of tools (fig. 23). The floor has been roughly chopped underneath and has distinct traces of plane use on the top. We found traces of axe use 15 cm long.

The tool traces remaining on the keel are not as clearly defined. On one side it’s been roughly chopped, while it has been planed in other places. Have the various craftsmen been in a hurry? The traces of axes are about 15 cm long and almost straight. (fig. 24)

It was very difficult to find traces of tool use on the stems. Our present day woodcarvers have many different types of irons to choose from when performing their art – but did the Vikings have the same choice?

We did find an interesting trace on the bottom part of the stern stem. It appears that a compass had been used for marking. Why was the line still there? Was the work not completed, or the marking wrong?

It was very difficult to find any traces of tools on the exterior surface of the planks. After diligent studying we finally found some traces of a plane about 25 mm wide.

After completing this work, we proceeded to the storehouse of the Museum of Cultural History to search for tools to match the traces and tasks that we could emulate.


Our specifications were:

         •        They were to match the tool traces on the Oseberg ship

         •        They were to be about the same age as the ship

         •        Preferably found in Vestfold, Norway

         •        They were to be well preserved

Fortunately, Norway is rich in tool finds from the Viking age. Many of the tools have been found in graves along with other objects, which means they can be dated quite accurately. We had hoped to find boat builders’ graves, but the objects rarely present a clear picture of the dead person’s profession. However, one grave stands out. (fig. 26). Several objects show that a boat builder has been laid to rest, or perhaps sent on to Valhall to continue his work. There are several tools that could be used to build ships.

All the tools used for the shipbuilding have been made according to our sketches, drawings and finds from the Viking Age. (fig. 27 and 28.)

In a later article, we will discuss in more detail that various types of tools that were chosen for building the reconstruction of the Oseberg ship.

The details

The details are an important factor to consider when creating a replica where the overall impression is important and the building process itself will provide us with new knowledge.

The old photographs on glass from the excavations have been extremely useful to us. The pictures have incredible depth and sharpness and we have been able to zoom onto the smallest details.

We have used these photographs to perfect the small details where the strakes meet the stems. The pictures have been enlarged up to a scale of 1:1. Using these images, we have been very close to the original. We were able to clarify how the inlet between the strake and the stem were made. We soon found that the work had been somewhat inaccurate when reconstructing the ship at the Viking Ship museum (fig. 29). The strakes did not have the original recess on the curve (fig. 29). We therefore used a photo in 1:1 from the excavation (fig. 30 and 31).

The rhombus-shaped discs

We also used this method when working on the rhombus-shaped clinker discs. The excavation photos from 1904 showed that the clinker discs in the stem area were on the outside and rhombus shaped. The holes for seams were square and about 7 mm wide.

The original Oseberg ship does unfortunately not have much of this aesthetic detail. During the reconstruction only square discs were used (fig. 32). After extensive studies of the excavation pictures and videos taped inside the ship, we have established in which areas of the ship these rhombus shaped discs were used at the time of building.


We believe that our work up to now has proved that experimental archaeology not only gives us history in an educational/entertaining manner, but also encourages new questions and adds new knowledge to science.

At the time of writing the work is only half finished, and we have already found several exciting details about the Oseberg ship that we intend to relate at a later stage.

There will undoubtedly be many more details to study during the building of the replica. The Oseberg ship is the major source of understanding the Vikings’ shipbuilding. It’s a three-dimensional history book – and we have so far only read the first chapter.

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News related to the building process