Hastings Yacht Club or Blind Bight Boat Ramp on Google Maps (satellite view and 360 photos)
look similar to Inverlock Boat Ramp - i.e. worth trying
...unless someone already had bad experience there or sailing is forbidden?
Looking for flat water spots
Inverlock is almost 2 hour drive and those 2 spots are twice closer, which makes them attractive.
I can usually spend only half a day for a windsurfing trip and not the whole day
Any advice?
Thank you!
No. Reef island is as far as I've got. There is a 5 kt speed limit at the boat ramp I believe. Good luck as I'm always keen to find something that works in a northerly
It has a huge tide and low tide is very low. Turns into small channels that is really only for power boats. Cowes yacht club run a race around French island for the cats. I will ask some of the guys, they race for something like 8 hours straight and run into the sandbanks around the other side
Yes. The Eastern Channel, beside French island on a very low tide and West to NW wind can have an amazing speed bank, but the tides are rarely low enough on those wind directions. We tried it out quite a few years ago (2008?) with a charter boat from Warneet, so access is really boat only. Has huge potential if you line the wind and tides up. 
I finally found the post from when we did an expedition to Westernport Bay, Eastern Channel on 04/03 2009
www.seabreeze.com.au/forums/Windsurfing/Gps/A-Bit-of-an-Adventure
and on GPSTC: gpsteamchallenge.com.au/sailor_session/show?date=2009-03-04&team=16
I also did a tinny boat trip a few months later with Tom Chalko and explored right down past French Island. Not much more to report except what we already knew. It needs a very low tide, and that is rare to never on a strong NW wind. 
I'm still searching for the video my son made with no luck so far. 
