"Flotsam and jetsam": Did grandpa use flotsam to build his barn?

Wikipedia on flotsam and jetsam:

• Flotsam is floating wreckage of a ship or its cargo.
• Jetsam is part of a ship, its equipment, or its cargo that is purposely cast overboard or jettisoned to lighten the load in time of distress and that sinks or is washed ashore.

At the island of Långholmen close to Runmarö north of Nämdö, there is an old "fisherman's croft" with an old barn. A thick plank in the barn wall draw the owner's attention: Where did it come from? It was heavily infested by the house longhorn beetle, so only chance to measure it was to cut off a slice from the plank. With a sufficiently large ground surface there could be a chance to find a measurement path between the windling grub tunnels.


I have measured three radii from that plank. The .rwl file is available as WBERG.rwl

An analysis was run in CDendro with a collection of several members, each representing a mean value curve from an area in Sweden, Norway, Denmark, Estonia and Finland. The sample was selected as the reference and the analysis done as a Test Towards UNDATED Reference ("With condensed report" checked!) which gave these best matches for each member:

                  T-    Over 
           Corr   Test   lap  Year 
all...     0.36   5.35   193  1736   based on 37 members 
swed023_   0.54   8.96   193  1736   940    1 Jamtland, historisch proj EXTRAT. - no PCAB 
NFinland   0.46   7.21   193  1736   Northern Finland 
EXFin002   0.46   7.19   193  1736   Fin002 N.Finland (EXTRATERR) 
SE006-La   0.42   6.48   193  1736   Lappland, Lund (EXTRATERR) 
NKarelia   0.42   6.44   193  1736   North Karelia, Finland 
_ 
FINL2_4_   0.34   4.96   193  1866   SouthEast Finland 
SödraDal   0.33   4.85   193  1736   Södra Dalarna,  Axelson, Israels. PISY 
DALARNA    0.31   4.45   193  1736   Dalarna, Lunds universitet (EXTRATERR) 
... 
Year numbers occurring more than once: 
 1736    9 
 1896    3 
 1860    2

With the reference (the plank) then dated to 1736 and with only the five best matches of the collection, then the condensed report of a "Test towards reference" gave:

                     T-  Over
            Corr   Test   lap
 all...     0.57   9.47   193   based on 5 members
 swed023_   0.54   8.96   193   Jamtland, historisch proj EXTRAT. - no PCAB (1107-1827)
 NFinland   0.46   7.21   193   Northern Finland (1410-2001)
 EXFin002   0.46   7.19   193   Fin002 N.Finland (EXTRATERR) (6-1993)
 SE006-La   0.42   6.48   193   Lappland, Lund (EXTRATERR) (-309-1993)
 NKarelia   0.42   6.44   193   North Karelia, Finland (1472-2001)

With that high T-values the dating to 1736 can be considered correct and the origin of the tree is somewhere along the coasts of the the Gulf of Bothnia (North of the real Baltic).
With at least 14 unmeasured outer rings, the felling year of the tree shifts from 1736 to 1750, though we do not know how much sapwood that has actually been cut away! Anyhow it seems that grandpa really used some flotsam timber that "blessed the coast" to build the barn! Perhaps that type of planks which were used to cover the openings to the hold (the cargo space) of a ship.