In the 1960s the shipyard in Aalsmeer was experimenting with a number of semi-standard designs and also took on some useful refitting projects on both motor and sail yachts. Johan de Vries prepared a large number of designs for motor and sailing yachts. Several were built on spec. and sold at boat shows, including the 19.80-metre Katja in 1966 and the 24.50-metre Ale II and 17.26-metre Mi Do II in 1968.