I have added what should be the last diagram to my original post in this topic. It shows the course as it would be if it was laid out as per the markings on the lake side. These were kindly taken by Ian Phillips and George Roberts recently, so thanks for doing that in “brass monkey” weather. You will notice that’s this layout has 9mt clearance from the bank sides.
The peripheral length of this circuit is 173.59mts.
One puzzle is if you compare this circuit to the one taken from the Google Maps ariel view (which I am told by David Harvey is from the 2018 Nationals), you will see that they are rather different. I can’t explain this.