Gday Cyrille, hope you enjoy your sailing around here. We have a club at Marmong Point (on George St) that meets on Saturdays at 1:30pm. We do organised Formula racing, plus slalom when the wind is good enough. Feel free to come along and say hello one weekend.
I have a couple of questions for the people who are on the east side of the lake. Was having a look around TheWindMap and found the spot launching from next to the Swansea caravan park:
thewindmap.com/wiki/index.php/Swansea_North-Australia_%26_New_Zealand1) Is this the fabled "sand islands" sailing spot?

2) How deep is the water? Is it very tide-affected? Can you safely run a 36cm+ fin across the whole area?
3) Does it only really work in a NE for speed runs? Too choppy in a westerly?
4) is this where all the kiters launch from? I have seen a lot of kites in that direction when sailing from Coal Point.
As much as I love my local spot at Marmong (and the rocks and razor fish), i'm always on the look out for somewhere new to sail.
cheers
james