same way. What I do is as soon as I let the anchor go my wife runs into the pilot house and pushes the MOB button. Once we get settled I change the MOB to a way point and set the anchor alarm off of that way point. As long as we don't forget to hit MOB button we're OK. The problem is when we come into a crowded anchorage and we have several boats around us we sometimes don't pay as close attention to her leaving the helm as we should. Then we regret it later. Try and change a MOB to a WP. If your plotter is set up so you can do that it should be easy to get your alarm pretty close.