The boat was built by Jachthaven Zuiderzee in Volendam (The Netherlands) not a lot can be found about them around the internet. But I know that a couple of hundered were made. The boat constist of two halfs that can be hooked togeter at the keel, then clamped with stainless steel clamps at the gunwale. (see pictures below). You would think that this is a leak-prone design, but the indepentant halfs actually float by themselves. The construction consists of plywood reinforced by 2 cm structural beams to connect the plywood.
The boat is rigged with an aluminium mast and a Marconi or Sloop type rig with a Jib. The main source of information I could find is this article from the NRC Handelsblad (24 feb, 1972):
Zeilboot is tevens roeiboot Op de komende HISWA-tentoonstelling in de Amsterdamse RAI zal ook deze 68 kilo wegende zeil-roeiboot te zien zijn. Deze Twin-Dory", ontworpen door de gebroeders Cobe-lens en gemaakt op de jachtwerf Zuiderzee in Volendam kan als zeilboot worden gebruikt(zeiloppervlak 8 m2), zeer eenvoudig in twee stukken worden gedeeld en dan als roeiboot dienst doen.
A newspaper snippet from the NRC Handelsblad (1972)
The current state of the boat, I am currently making some repairs and painting the inside and out,
A picture I received from the previous owner. Here you can see how she looks with sails up
The two halves mounted together with the stainless hardware.
The two halves of the boat make up a 4,40m boat.
it stores easily with the two haves nested togeter. I hoist it up to the ceiling
The mast constists of an aluminium profile. Very standard 1970's stuff.
Another view of the top of the mast.
The anchor point for the forestay.