It seemed to me that the rudder was not quite effective enough, but perhaps this is a characteristic of light boats. I often had to let some sail out to turn upwind. Since buying the A600 kit I have bought and sailed an EC-12, which is much larger and heavier and has a huge rudder so perhaps I have come to expect too much.
Pat at Aquataur replies:
With more sailing you will find that the rudder is fine. If you can get hold of a dinghy sailing techniques book you will find that the model behaves like the fullsize and it will teach you all the tricks of sailing this type of boat, using the crew's weight to roll tack for example. In this way that you will get the most out of your A600.