A combination fish finder, chart plotter can get you home and out. Not like radar but you know where you are and where you are going. Travel in fog conditions requires a speed where you can stop in half the visible directions, maintain extra lookouts, sound fog signals even if you are anchored and listen for signals from nearby boats. Simply a prolong blast less than two minutes apart while underway. Not underway two prolonged blasts two seconds apart. If you are fishing with long lines or side planers three prolonged blasts two seconds apart followed by two short blasts. A prolonged blast is is four to six seconds long. I am not a sea lawyer.