The strength of Vasa's timbers is substantially reduced in a number of locations, according to new research. An improved support design is the goal of the current research project, Support Vasa.
Vasa sits today on keel blocks with supports along its sides, in the same way a sailboat would be supported on dry land. The current cradle dates from the 1960s and was added to in the 1990s, but not sufficiently. Research into the ship's specific properties will provide basic data in order to build new support system.
Deformation in hull
A better support has been needed for Vasa for a long time. The museum carpenters have noticed that the ship timbers are deforming and twice annual position measurements show that the ship is gradually distorting.
Cross-disciplinary research is showing that there is a clear connection between the chemical status of the wood and its mechanical properties.
The wood is showing signs of chemical degradation in a number of places in the hull. There is also evidence that the wood has lost strength. The ship's ability to carry loads in these areas is decreased by on average 40% compared with fresh wood. In some places, this figure is as high as 80%. The numbers clearly show the need to support Vasa in a better manner than is the case today.
Thorough survey necessary
A huge amount of data must be gathered before a new support structure can be built. Theories need to be formulated and models quantified, tested and substantiated. How the wood in itself and the ship as a structure are changing chemically and mechanically over time must be plotted.
This work forms the basis of the research project Support Vasa, conducted in 2012-2016 in cooperation with, and under the leadership of the Institution of Applied Mechanics at Uppsala University. By the end of 2016, the research phase of the project was concluded and in 2017 the next phase started, focusing on the construction of an improved support system.