Hi Conan,
I was over that way last weekend, it was at high tide when I was sailing over the bank, near the marker beacon. It looked pretty deep, around 6 feet or so, hard to tell accurate depth. It wasn't until I checked out the area on google earth that I saw breaking waves and the image was watermarked 2008, so I guess it's a fairly recent shot of the area.
I guess you don't need the bank to be fully exposed to break the chop, but what interested me about the google earth image is how much of the NE seabreeze chop is broken even though the bank doesn't look fully exposed.
I think next spring/summer when I cant get a park at Kyeemagh, it might be worth a trip if the tide's right. Even if the tide's high, it's pack away the gps and head out for some b&j at kurnell. You'd still get some good times for the 1hr, NM and distance. Maybe even some good alphas in behind the groynes. Another HUGE plus about kurnell vs kyeemagh is there's NO jetskis. But that thread's been done many times before...