So yea I agree you should know your boat how it feels and be aware of the differenct sounds your boat makes, not just with Anchor situations. However, anyone who doesnt use one is going to wish they had at some point in there sailing life. Many said what there chosen product is, but not why !!. So mine in Anchor Pro and I have been using it for 10 plus years. Why Anchor Pro... Firstly becuase it can tell me even when Im off the boat that it has moved outside my geofence area, Most others cant do that. Secondly, I can segment off the geofence. So for example if I anchor in a spot where Im sure the boat will not do full circle, but if it did for some unplanned reason I can make this area outside the geofence, because it doesnt have to be a full circle. If Im on shore I can interogate Anchor pro and I can tell based on its distance from the anchor whether by vessel is puling hard on the anchor perhaps due to the wind increasing, or if it is sitting there nicely. A friend of mine whom I convinced to to use one, recently ended up on the reef, becuase he didnt use it on a mooring which broke. So I use mine everywhere all the time excluding on a marina. Lets talk about false positives mentioned above. My experence suggests that there are a combination of reasons for these. 1) The phone itself. I have it on two phones, one is particularly bad, so yep not all phones are as good as the next. 2) Is the location of the phone, its GPS needs to be able to gain access, 3) is people don't set the radius of the geofence to a reasonable number based on the accuracies of the GPS 4) the phone goes flat etc etc. So in my case I chose to set quite a fine radius and that does result in the odd false positive, because when a 30knot squawl comes through the anchor chain straightens out and perhaps moves 2 or 3 meters (not dragging but simply diggin in more) and yep it will go off if it set fine. So for example in a tight space, or perhaps if the boat swings 180 degrees and it becomes a lee shore, there are many examples. But while I might get the false positive and getup to check or adjust it from then on I sleep in piece. Getting any movement off sent tpo me off the boat is also some comfort. So its another tool, cost very little or in some cases nothing so everyone should be useing one,