It runs the radar through all the ranges to test and adjust the radar video levels. If you run it at the dock, all the close in radar returns causes the radar to turn down the sensitivity. When you take the boat out on the open water, the baseline set will be lower than you want it to be and the radar will not be as sensitive as it could be. You can't adjust it better than it comes out of the box. I don't recommend doing optimization unless you suspect it needs to be adjusted, then only away from the dock.