News about the Osmund wreck
21 March 2020 11:03
For two years, Vrak's maritime archaeologists have investigate an exciting wreck loaded with osmund iron in Stockholm's southern archipelago. Here some news what has come out.
The construction is old-fashioned
The ship is a heavy clinker-built ship about 20 meters long and 7.5 meters broad, and is unique in many ways that we can see. The planking is held together only by clinker nails (rivets) and the construction is old-fashioned for its time. It looks like a wale or rubbing strake has been nailed to the outside of the planking, which gives it an appearance we normally associate with carvel ships.
The beams and their supports are similar to what we see in many medieval ships; no real deck beams, but more like a strengthened partner system for the masts. Some of the through-beams have enlarged heads, which is also typically medieval. Drop-shaped deadeyes are a feature that disappeared in the early 17th century.
The ship had two masts, and the mainmast is still in place, rakes aft. It reminds of a ship from a century later, which one can see in an engraving of Riddarfjärden, Stockholm from 1647. The ship had two decked areas, one aft (where the hearth and a copper kettle are still visible) and one at the bow. The middle of the ship is filled with over 20 casks. Most contain osmund.
Osmund iron and bar iron
This crude product from initial smelting was cheaper than the refined iron produced in the forge or blast furnace. The blooms were hacked apart into smaller clumps, called osmunds (from which it gets its name).
Vrak's maritime archaeologists have also found some bar iron which was very nicely forged. This is the product of a water-powered trip hammer. The earliest evidence we have for this kind of production is in the Vädersol painting from Stockholm of 1536, which shows similar bar iron being made. The wreck is dated to the 1540s, partly on the basis of a three-footed kettle (which unfortunately disappeared due to plundering last year).
We have taken samples from the hull, the casks and the iron. It was possible to date the casks, which are made from wood probably cut in the 1540s in the eastern Baltic. We know of two other wrecks with osmund cargoes, one in Poland and one in Germany.
Iron has been and continues to be one of Sweden’s most important exports, therefore it is a little strange that so few wrecks have been found with osmund cargoes. Even late wrecks with iron cargoes are surprisingly few in the archaeological record.
Collaborative research project around the Baltic Sea
We are now trying to stitch together a collaborative research project with Poland and Germany, as well as with Jernkontoret, the Swedish commercial organization for iron producers. These wrecks are one of the most important finds for many years for research into the history of the Swedish iron industry.
The wreck is largely intact, fully loaded, and has personal possessions which can show us what life was like on board a large merchant vessel in the 16th century.
A ship built in an old-fashioned way during a period of dramatic development in Sweden and northern Europe. We think that a project around this wreck could be followed from the new museum, Vrak – Museum of Wrecks.