Anchor watch guide: setup, GPS and remote alarms
An anchor alarm radius should fit the anchorage and the movement you can safely allow. A value that works in an open bay may be unsuitable beside a shallow patch or another boat. In AnchorHoy, the radius is measured from the estimated anchor position, not from the boat's starting position.
Start with the anchor at the centre
The anchor icon is the centre of the watch circle. A 50 m radius describes an area extending 50 m from that point in every direction. It does not mean another 50 m beyond the end of the chain. Check the map when starting a new watch: an incorrect estimated anchor position moves the whole watch area and changes what a boundary crossing means.
Chain length is not the alarm radius
Chain length, depth and the wind direction you enter help AnchorHoy estimate the anchor location and describe possible swing. They do not automatically increase your chosen alarm radius. The estimate is not a seabed measurement: chain shape, tide, current and the phone's position aboard can differ from the simplified model. Check the result against the actual anchoring situation.
Account for the whole boat and nearby hazards
The GPS marker represents the phone aboard, not every part of the hull. Consider the phone's distance from the bow and stern, other boats, changes in wind or tide, and the space needed to act. A circular boundary cannot describe every irregular hazard. If normal movement and GPS uncertainty leave too little room before a hazard, changing the number in an app does not make that anchorage safe.
Read GPS accuracy before choosing a tight boundary
The displayed GPS accuracy is an estimate of position uncertainty. A fluctuating position can approach or cross a tight boundary even without equivalent boat movement. Wait for fresh, sufficiently precise fixes and compare the track with what you observe aboard. Never enlarge the radius merely to silence an unexplained alarm. First check the boat, the anchor estimate and the location quality.
A 50 m example, not a universal recommendation
Suppose you enter 15 m of chain, 3 m of depth and a 50 m alarm radius. The alarm circle still extends 50 m from the estimated anchor. Those inputs alone do not establish that 50 m is suitable. Inspect the available clearance and allow for the vessel and local conditions. This example explains the app's distance reference; it is not a recommendation for chain scope or anchoring technique.
Check the watch before leaving the boat
Confirm that the anchor is where you expect, the radius matches your intention, GPS time is advancing and the reported accuracy is reasonable. Pair the shore device and send a test alarm with its screen locked. Repeat the checks after changing devices or settings. AnchorHoy supports your watch; it does not replace seamanship, observations aboard or a plan for responding to an alarm.