Here is my exact setup I use for BEACH. It's a little quirky but if you watched my "Deep Silver at the Beach" video you saw this program hitting silver coins at incredible depths!! I have found that the M9 and M8 coils are too small for coverage and on my highly mineralized beaches the M15 loses depth as it has to drastically compensate during ground balance. The M11 coil actually hit's the deepest on my beaches. If your sand is mild try the M15 for coverage and depth. Feel free to ask questions. I have included a blank template that you can download as well for your own use!