NGA: Anchor Alarm

NGA means Not Going Anywhere. It is a practical anchor alarm for sailors. Drop the anchor, mark the spot, set a swing radius. NGA monitors your boat's GPS position, including from the background, and raises a loud alarm if the boat drifts outside the safe circle, even when your phone is on silent. HOW IT WORKS - Set the anchor point from your current position - Tune the swing radius by hand, or size it from depth, rode, and bow height with the scope calculator - For a tight anchorage, limit the swing to an arc instead of a full circle - NGA watches position continuously, on deck or asleep below - If the boat leaves the safe zone, a loud alarm sounds and keeps sounding, even on silent, until you acknowledge it BUILT FOR REAL CONDITIONS - The alarm plays through the audio channel, so it is heard with the ringer off or the screen locked - GPS accuracy is shown plainly. Unreliable readings update the display but cannot advance the alarm - Breach detection allows for GPS error on both the live fix and the anchor-set fix - A short confirmation window filters out single stray readings before the alarm escalates - A low-battery warning reminds you to keep the phone powered through the night - If iOS stops the app mid-watch, the session restores and re-arms on next launch ON THE WATER - Watch the boat's swing trail build on the map, in standard or satellite view - Correct the anchor point or change the radius without stopping the watch - A return-to-anchor compass points the way back to the boat by dinghy GLANCEABLE - Live Activity on the Lock Screen and Dynamic Island shows distance and status - Anchor watch history, with a drift graph for every past session PRIVATE BY DESIGN - No app account or analytics - Local anchor monitoring works without enabling remote monitoring - Optional remote monitoring shares watch status through your private iCloud database NGA uses background location only while an anchor watch is active, and plays audio only to sound the alarm.