@Chris
These pics are taken from Lake Magnolia, Smithfield NC. They balls are not filled with water or weighted down. Most that run this course never have an issue moving around them rather than over them. That said, I'm new to the 6 ball game so I've run over them before.

I still have my course on Jordan sunk, will have to retreive it soon, another month or so after I winterize the boat. I'll use someone else's boat to pick up the course. Its way to messy to put in my Supra.