Jan, went to the cat-club and asked a Dart 18 owner where the vin-numbers are.Now here's the funny part;
They are hand-written inside the hull. So open a port-hole and you can see the number.
Checked it on 4 other Dart 18's, and he is right. Makes sense, they all come from the same plant.
The Topcat F2 is to small for light wind fun, build in Germany though and they still excist ! http://www.topcat.de/de/
Also they come with 3 different main-sail setup, Kids, Cruise or Race so which main comes with it?
Its close to a H-16 and not much fun in light winds with your 84Kg weight.
I suggest you get the Nacra 5.5(first choice) or the Dart 18 (second choice) .