The southern stretch of Canaipa Passage, which runs up the western side of North Stradbroke Island in Moreton Bay, appears to be silting up.
My house on Russell Island overlooks the area and in the past two years I have noticed that two sand banks have been growing steadily. While this is no surprise, given that North Stradbroke is the second-largest sand island in Australia, it is now having an effect on the navigability of the channel.
In the past two weeks I have seen six yachts run aground at two keys points. I have highlighted them with arrows in the chart below. The first is at the red marker near the Slipping Sands fishing huts, which has always been a problem for deep-draft yachts at low tide. However, I have also seen three yachts run aground, and turn back, in the short stretch between the last green marker and the first red marker directly off Sandy Beach, where you can see a dozen or so beach cats parked.
All six yachts were able to back off the sand into deeper water, but all turned back to the south, deciding not to wait for a higher tide.
My boat is in the Krummel Channel at the north end of the island and I haven't been through Canaipa Passage for 18 months, so I can't give you exact depths.
However, even at the lowest of tides, catamarans have no problem at either point. The yachts I have seen run aground looked to have a draft of 1.8 to 2 metres so I'm assuming that there is about 1.5 to 1.6 metres at these problem points on low tides. If you have passed through with a depth sounder in recent times and can give some more definitive depths, that would be appreciated.
The tidal range in this area varies from around 0.8 to 2.0 metres, depending on the phase of the moon. (Use Brisbane tide times in your calculations.) So my suggestion to owners of deep draft yachts wanting to transit from the Gold Coast to Moreton Bay is either to use the passage up the western side of Russell or time your run – come through Canaipa Passage on a rising tide and at least two hours after low tide.
Any further information readers can contribute will be appreciated.
– Roger McMillan, editor