This App will allow you to fix your boats location and to set a maximum scope that you want the boat to drift before triggering an alarm. You can elect to run in silent mode with just a warning message appearing when the set scope it exceeded or you can elect to use the default alarm sound.
The distance drifted and bearing to the set anchor point are shown.
There are two views, the default test view and a map view which will show the anchor point and the drift track which will be in green if the boat is withing the set scope and red if outside.
There are settings options to enable you to choose whether to use feet or metres and whether to allow the app to run in the background etc
In addition to the alarm you can elect to have an SMS message sent if the boat drifts outside of the set scope. Only one SMS will be sent. If you reset the anchor position then another SMS will be sent of the boat drifts outside of the new scope.
Added range circle to show better your boat's position relative to the scope that you have selected.
NOTE: For those people who don't understand, GPS does not work indoors and it uses up your battery. This is NOT the fault of any GPS based App.