it depends. I just returned from a sailing trip and if you are in narrow waters you can compare your position with land marks, bridges, harbour structures and s

it depends. I just returned from a sailing trip and if you are in narrow waters you can compare your position with land marks, bridges, harbour structures and so on. Worked out great. I also used Navionics before, worked great as well. I anchored over a small cable without looking at the iPad and caught it. Navionics displayed the cable under us.