There are plenty of times that you will want to know your anchor is holding and not dragging.

These include:

• When sleeping on your boat
• When diving from your boat
• When snorkeling or swimming off your boat
• When leaving your boat at anchor and going ashore 

The chart plotter on boat will likely tell you this information however you may be out of earshot or eyeline of the plotter or, if you are down below in you bunk you may want something closer to hand that will wake you if something is awry.

This is where a smartphone app comes into play.

We have been using the free edition of Anchor Pro and it has been great

It allows you to 'drop' an anchor and then set an allowed distance to swing or drift or drag. Once that limit is reached (according the the GPS on your phone), an alarm sounds.

You can see the location of the anchor and the location of yourself on the map. Here the anchor (anchor icon) and smartphone (blue dot) are in the same place:



You can also see the distance and bearing to the anchor in plain text:


The free app has served us very well and we can recommend it.

What is missing is the ability to watch your boat when ashore (the last bullet point at the start of this article) - for this a different approach is required. We are refining our solution here and will report back when it is working reliably and cheaply!