Gary,

I'm glad I'm not the only one having this problem! I've decided above about 18kts its just too difficult to stay in proper control and so don't wire above that. Keep trying now and again and keep wiping out. No doubt this is more to do with my skill level than anything else.

I just find that the tiller is so sensitive at these speeds and when being thrown about on the wire I cannot steer carefully enough. - the line is too fine.
Good fun trying mind....