The link to the old Navionics Web App. on the left will work at present, but will ultimately die. In that event a useable version is here. Navionics web app.
Click here for our survey around the Annulus and Wedge done on 12 February 2018. NB it has become shallower since then as evidenced by a grounding between these structures.
and here is detail of the Marina (RGYC) in Geelong.
Navigating Port Phillip Heads can be challenging and local knowledge should be obtained. In particular, large ships make a sudden turn off Lonsdale Bight to follow the main shipping channel. The approach from offshore favoured by yachts is the “four fingers west” channel. Here is just one of the diagrams available. See also location of Corsair Rock, by scrolling down to “Hazards” in the “Skippers’ Essentials” page.