Yeh I hit that coffee rock about 12 years ago. From a full planing hull to a dead stop with 3 small blokes on board it was bloody violent. I had been up that strach many times before hitting that on low tide. I did actually see it out of the water once about a year later on a king low tide.
Maybe they need to drop buoys along the shallow area to warn boaties it is very very dangerous.
Cheers
Chris