Mr. Keegstra, an experienced yachtsman, owned a Norwegian folkboat, which had not enough comfort. A first design was made according to the owner's wishes and resulted in a 10,10 m steel, round bilged, ketch rigged, sailing yacht with a traditional long keel/rudder arrangement similar to the Norwegian folkboat.

Later the design has been changed and a closed teak wheelhouse was added which gave the yacht a motorsailer appearance. This design was named "Sirocco" and taken into production by Mr. Van der Zwaag of the Van der Zwaag yard (later RSB) at Irnsum, Friesland. After a while the hull was lengthened by 0,6 m in order ot accommodate an aft cabin. This version has been produced with various interior lay-outs within the same steel hull till mid seventees.