We used 1”X 10’ aluminum conduit, we cut it in half and drilled a 5/16” hole about 1.5’ down and put a ¼’x1’piece of rebar. Then we drilled ¼” hole about 2” down and spiced a shot 3/16” stainless cable on the conduit. Then we drove the conduit 4.5’ in the ground, checking the location with the total station as we drove the conduit in the ground. We belled out an area large enough for an 80 pound sack of concrete. Each buoy location is within a couple thousands. We tie a bungee cord to the top eye of the cable for the buoy.
Course is 18 years old.