beginner having trouble with higher winds

[Charliem]

I am a beginner windsurfer. I have a Nova 180 board and a 6.5m sail that I am told is not designed for a lot of downhaul. I have become reasonably competent over the summer at windspeeds just short of planing conditions. Recently in higher wind conditions I am having trouble getting the sail powered up. I end up having to push hard with my forward hand and pull back hard with my back hand just to control the sail. Any suggestions would be appreciated.