I sailed down to Sydney yesterday in a mate's S&S34 and had a very interesting experience. After rounding Barrenjoey the headland disappeared in the fog at about 2-300 metres. We next saw land at North Head at about 300 metres. For much of the time we had 100-200 metres visibility. From Dee Why down we had a large ship somewhere to the south/southeast from his fog horn. We never saw him and he didn't move, we surmised he was waiting to enter Sydney and as we got into the harbour there were 3 large Switser tugs waiting, presumably for him.
A few stink boats loomed out of the fog, one at about 100 metres, doing 20 knots or so. You hoped they had a good lookout.
Steering was purely off the compass and nav via DR/GPS. We were making between 5-7 kts so had good steerage and stayed close inshore to avoid commercial shipping. Our lookout was 100%.
I have never seen a fog like this off Sydney, caused by cold water upwelling off the coast and the warm moist north wind. Even the breeze which was up to 12-15 kts didn't shift it.
It was quite magical and a great experience.

It was quiet now you mention it. You could hear other boats, even yachts motoring north, and sometimes didn't see them.

Had a few days with thick fog right up to midday before it burnt off. Used to have amateur fishermen come up to us at the "Banks" and ask what time we were going home. They would sit on our stern as we steamed home. At the entrance we often gathered a few on the stern for the trip up the river. Radar and GPS are great but in a fog its still easy to get disoriented. Always steered on autopilot in fog, even up the river to the wharf and kept my head vertical. Some fishermen have come unstuck steering with a large wheel and bending over when turning it and have their "gyro" topple.

One morning a long time ago before GPS I ran aground on the way to work. When the sun came up and burnt off the fog I was not the only one. Couple of trawlers had gone off and ran aground in weird places!

Fog from Sydney to Broken Bay

We were out there as well......actually 2 days in a row...Syd-Pittwater Saturday Morning, and then returned Sunday morning....the experience was amazing, Vis down to 100-200 mtrs max at times, Saturday was wet wet wet....Sunday was Dry and warm....again strange...Oh did I say......this was my first ever Ocean going experience, yes so the first time out of the heads, I never got to see a thing, however in someways, I saw so much of nothing, which was actually quite nice...though hopefully next time I get to see something.....