Just moved to Brisbane. Have been driving boats in all conditions including IRB's in heavy surf. I know how to read waves and banks. I did what you said and V-lined straight for the tip of Moreton (northern) at low tide on Sat morn. Lets just say I wouldnt reccomend it. Only one sandbank was a problem. It was about 2 foot deep... and I did pick it. Had to slow right down. But whos to say that bank wont have more sand on it by next trip. From now on Im going to use c-map I think.
I have a merc 75 and took a jerry can just in case as we went to flinders reef. And I put the can in on the way pack just for security. Prob used 75 litres for around 140ks for the day. But we did a lot of exploring. Plus the 4 stroke should use less.
And use the beacons. Oh really do watch out for those big ships. They move real quick. As there wake is aweful. I had wake from the SW from a boat and a solid 1m of chop from the NE. While fun to wathc. It really took me back to surf club days. Like they all say. I would get used to your boat before you hit that stuff.
Moreton didnt fish well yesterday. But driving there would shore beat the $400 dollars it would cost you to drive your car and boat on a ferry
Dick