An anchor watch does one thing: it tells you when the boat is no longer where you left her. This is how to set one up, what it does while you sleep, and what to check if it ever seems quiet when it should not be.
Four things decide whether an alarm can actually wake you. The watch screen warns you about each one, but it is worth setting them once and forgetting them.
Drop the anchor, let the boat settle back on her chain, then open the app and choose Set Up Watch. Six scenarios cover the usual ways of lying:
Then place the anchor: at your current position (the usual choice, taken the moment you tap), by coordinates, or on the map. Coordinates can be typed the way a chart writes them, 43°07.4074'N, or as plain decimal degrees.
If the anchor is already down and in the wrong place on the map, tap Move: drag it, nudge it a metre at a time, or type the position.
The radius has to cover the rode you have out, plus the length of the boat, plus what the GPS itself is unsure about. Set from depth & rode does that arithmetic: give it the depth and the scope you veered and it proposes a radius.
Too small and a wind shift wakes you for nothing. Too large and the boat is aground before anything sounds. If in doubt, watch the track for an hour: the app draws where she has actually swung.
A circle is often too generous. Two tools narrow it:
The phone's own GPS is the default and is usually enough. The app can also take a position from a Bluetooth receiver (Dragy and other u-blox units), from the boat's own instruments over NMEA on the network (TCP, UDP, presets for Vesper and Digital Yacht), or from Signal K. Add them under Settings > GPS Sources. The watch falls back to the phone if an external source goes quiet, and says on the card which one it is using.
Every watch has a share code. Enter it on another phone (or open the web watch in a browser) and that device follows the boat and receives the same alarms. Use Send Test Alert to Monitors in Settings to prove it: it now reports how many devices it actually reached.
By default a monitor only watches. If you turn on Allow remote control on the boat, a phone ashore can also arm and stop the watch, pause it, move the anchor and change the radius. Every such change is confirmed first, and the boat is told what happened.
The alarm starts quietly the moment the boat crosses the line and rises to full volume over about thirty seconds, so somebody awake can deal with it before it wakes the whole boat. A short excursion that comes straight back does not raise a confirmed alarm; twenty seconds outside does. Monitors are pushed the same alarm.
Snooze silences it for five minutes and keeps the watch running. Pause stops the alarm and keeps the anchor and the zone. Raise Anchor ends the watch.
Separately from dragging, the app chimes if the phone's battery falls to 10%, or if it has had no GPS fix (or, ashore, no report from the boat) for ten minutes.
The watch is designed to run all night on a phone that is not plugged in, but a full night of GPS is real power. Charge if you can. Battery Saver in Settings uses coarser GPS while the boat is holding, and switches back to full precision near the edge of the zone, while dragging, or when charging.
Settings > Send Feedback reaches us from inside the app, and anchor@blanck.hk works too. What helps most: the phone, the app version, and what the watch card was showing at the time.