Shit. So sorry for you, really.
And it is the second time in few weeks that I read about a big windsurf robbery in Scandinavia, and I'm so surprised, because I travelled all across Denmark and once up on the west coast of Sweden in the last three years, with stuff inside car but board over the roof without any locking or safety device, always thinking to be in the safer place of Europe.
The first robbery (read on HSM forum) was pheraphs mainly about the pricy car, but your it is clearly made by a windsurfer or someone expert about the value of windsurfing equipment...
BTW serial numbers at least of boards would be helpful, I keep an excel file with all s.n. right for the case of a board stolen. And now there are codes also on masts and sails.