There are a few good spots.
Most folk sail off 'Far Beach' or 'town beach'. There are tidal issues and it can be a long walk home having done it once or twice

. On a good NE you can head up to the mouth of the river.
We used to sail at Eimeo a lot (from the catamaran club) - not sure if any one sails there anymore.
There a quite a few good spots on the north side of mackay. Seaforth and Ball bay

on a great on North Easterly.
Bruised