That area is known as high risk. Please be careful!
In fact that "ROUGH BAR" sign on the structure at Chatham light refers to that area. Once the tide has fallen to an advanced stage, the sand is exposed safely and in fact I have stared at that lee edge of the bar many times wishing I could reach it. It's the peak flow times that are hazardous.
Every time I see that sign I think of how good it would look in a pub.