Ha, ha, ha... no, this is it. I will explain.
Look behind the boat in the foreground you will see a smaller boat to the left, it is a jet boat... draws about 4-6 inches. The real light colored water is about 12 inches deep, the dark edge behind is short grass on the bottom, in the shallows. Looks just like deep water and that grass fools a lot of folks. I did that once myself years ago, went around the "Island" and wham, was in the grass, like a floating ditch witch.
When you get into the grass you will do just as you describe. Grass is dark about 4 inches tall and bottom is white sand. Prop going through the grass leaves a white trail the width of the prop.
Nope, photo was from my boat, in about 8 feet of water. I draw 38 inches with this boat so I do my best to stay out of the shallow end of the pool. Making marks in the grass could get real expensive, real fast...
Ed