Set the location when above where the hook is set. Then set distance of chain put out.
I do keep phone plugged in while set at night. Agree with GPS accuracy being the biggest alarm. Can adjust this up.

I also set chart plotter to show "TracK", both on my iPad and the helm station. If Drag Queen goes off, looking at the track should relieve any doubt of dragging. Should be a black squiggly line forming a blob... if dragging, there will be a single line leaving this "blob".....(Thanks Warren)