Using very low tech but timeless techniques, we discovered a shoal right in an alleged navigable area yesterday! (Ran into it at over 6 knots).
The area is the Broadwater, between Moreton Bay and Southport in Queensland
. The exact location is 27d 42.20m S, 153d 21.64m E. This puts it just south of the high tension wire crossing, and about 50 metres W of a green channel marker. The best chart in my possesion (2011 date) shows (interpolating between nearby soundings) that the depth
should be around 3 metres at datum. In fact it is <2 metres near high water
, with the Brisbane
bar at 1.7 m. The shoal appears to be around 30 m in diameter, but I didn't do a good job of surveying in all directions. It consists of soft mud, and is near the junction with another channel, so it is an area subject to change. There appears to be navigable water
on both sides, but it is definitely deeper to the W of the shoal... that's how we eventually escaped.
At any rate, I thought other cruisers who transit this channel might be interested.