Findstuff, skypilot here. basically, smaller coils are WAAAAY better in trash and highly mineralized soil, due to the fact that they "see" less area compared to a larger coil, (kind of like low beam lights on a foggy night, the smaller coil will not "reflect" back to the machine the interference from trash and minerals, whereas the larger coil will be more prone to do so), and the depth loss is not as severe as you may imagine, in relation to size, because, if nothing else, the larger coil will by nature confuse the unit, while the smaller coil may not go as deep, it will be more accurate, in those conditions. An eight inch coil is a sort of compromise between depth and trash/mineral separation, while large coils are primarily used in places where objects will be deep, but not really close together. For instance: Parks, schoolyards, church and demolition lots, or where a structure has been razed, would be a great place for the smaller coil, while pastures, woods, less frequented areas (by modern folks), will be great for the larger coils. As for sweep speed, some units are adjustable for the user, while others are not, so experimentation is all one can go by. Hope this helps! Regards, Richard
And I am glad to help in any way I am able! Great hunting and good luck!! Regards, Richard
