it's surprisingly consistent providing the wind is ssw around to wsw - too much west and the hill blocks the wind. East can work too, though I've never sailed it in an easterly, but I've cursed it when I've been water skiing. The chop is fairly spread out and manageable. Hot days usually end up with a 15-20 knot seabreeze from the east by 3pm.
There used to be a dedicated windsurfing club launch spot on the southeast corner (pony club entrance) but it's been closed off by the pony club due to lack of use I'd guess. Too be honest, it's no great loss as the wind is a bit better down the powerboating end (powerstation end) in all sailable directions. By the time it's windy enough to sail, it's too windy for most powerboat users anyway and you've got the place to yourself.
I don't have any pix that show the whole dam, but I'll take a few next time I go down. Here are a couple more recent ones. The dam is about 1km wide at the narrow end and about 2km wide at the wider end. It must be about 2km long from end to end? The runs are long enough for me.
Cheers