Changelog (Android)

Behind the following button you can download the APK of a special version of the app. This version is intended for the use on device without Google Play Services and will not run on regular devices with Google.

It is intended for devices with a custom ROM, based on AOSP, or something similar without Google Plays Sevices.

If you like this special version of the app, I would appreciate a small contribution for development and support.

Your contribution will help to improve the app and to cover the running server costs. Many thanks !

Version 1.2.1

  • Die Beschriftung der Abstandsringe ist nun auch auf Navionics Karten in Fuß, wenn diese Einheit ausgewählt wurde.

Version 1.2

  • Navionics charts are now supported. Please keep in mind, that you need a current subscription with Navionics/Garmin to use these charts.

Version 1.1.4

  • Compass processing within the anchoring dialog works again now.
  • There is now a confirmation dialog when disarming the alert. This dialog can be switched off in the settings.
  • Improved stability.

Version 1.1.3

  • OSM chart will now be centered correctly after device rotation.
  • Numeric entry in the anchoring dialog will now be saved.
  • There is now a confirmation dialog when raising the anchor. This dialog can be switched off in the settings.
  • The permanent notification in the status bar can now be deleted on Android 13 and later.
  • With the compass button on the mainscreen you can now display a compass line.
  • The threshold level for the battery alert can now be set in the setting.

Version 1.1.2

  • Fixed a screen update problem with OSM maps.
  • Added a link to the homepage in the settings.

Version 1.1.1

  • Accuracy is now transmitted while mirroring.
  • Fixed a crash when starting the app on some devices.
  • Alert triggered by entering an exclusion zone while not anchored can now be silenced.
  • Changes of perimeter and/or anchoring location are now transmitted to the receiver.
  • Switching the screen on the receiver no longer disables the transmitter.

Version 1.1

  • Open Sea Map is now supported as an addition chart type.
  • Clicking the proximity Symbol now gives more information.
  • Custom alarm sounds now display the correct filename.
  • Some minor bug fixes.

Version 1.01

  • Fixed a bug when stopping the app.
  • Default anchor radius is now used in the anchoring dialog.

Changelog (ios)

Version 2.8

  • Compass reading of the device is not correctly shown in top right corner of the map.
  • Boat vector while moving is now also displayed on the Navionics map.
  • Improved the user feedback when downloading Navionics maps for offline use.
  • Navionics maps now recognize the selected unit (feet or meter) for displaying depths.
  • Navionics user can now set some chart options like in the Boating App. For this the "Navionics login" entry in the settings has been replaced with a "Navionics settings" entry. The former "Navionics login" you will find within the new settings page.
  • Auto anchoring now uses the NMEA heading if available.
  • Added the device distance from bow to the ship data settings. This is the same value as in the auto anchoring settings. If enabled in the ship data settings this distance will used to adjust the anchoring position when droping the anchor as well as the alert radius.

Version 2.7.1

  • Fixed a false error message when registering an userid.

Version 2.7

  • The option to keep track upon app start has been removed. Current track data will now always be kept. Instead there is now the option (enabled by default) to delete track points that are more than 1 nm away from the current location upon app start. Please keep in mind that having to many track data saved may adversely effect the apps performance.
  • There is now a new button in the toolbar to show your boats swinging circle on the map in addition to the alert circle, based on actual chain length and depth. See the help for more details.
  • You can now attach pictures to stored anchoring places.
  • Systemlog entries are now deleted after 5 days.

Version 2.6

  • Bearing and distance as well as the most recent GPS update time are now correctly displayed when the app is brought to the foreground.
  • The graphics on the map shouldn't spontaneously vanish any longer.
  • New experimental feature: Automatic anchoring. The App will drop the anchor automatically as soon as certain conditions are met. Please check the corresponding help page in the settings. This is an experimental feature still in development. Please let me now your experience with it.

Version 2.5.1

  • There is now a confirmation dialog for raising the anchor and disarming the alert. You can switch off these dialogs in the settings.
  • For better readability activated buttons now have a green background. This applies only to the 3D button style.
  • Mirroring: Fixed a problem that the receiver could not reestablish the connection once terminated.

Version 2.5

  • Perimeter alert, proximity alert and battery alert can now configured to use different sounds.
  • Added the possibility to use custom alarm sounds.
  • Distances can now also been shown in feet instead of meter. See Settings.
  • Added a contact form in the Settings.
  • There is a new style for the main buttons that you may find more intuitive than the old style. If you prefer the old style you can switch to it in the Settings.
  • Anchoring using the position dialog now works correctly at southern latitudes and western longitudes.
  • Anchor Sentry uses now Critical Alerts. Critical Alerts will play even when the device is muted or set to not disturb. The next time you toggle alert on, you will be asked to allow Critical Alerts. You can disable this feature in the settings.

Version 2.4.6

  • Fixed a color problem with the titlebar in iOS 15+.
  • Using the bearing/distance part of the anchoring dialog, once you start entering values manually in the bearing field, the compass updates will be suspended.
  • Other ships at anchor (on the server) no longer trigger a proximity alert if the last position update from the ship is older than 2 hours. It is then assumed that that ship left without properly raising anchor within the app.

Version 2.4.5

  • Fixed a problem in iOS 15 with not coloring the titlebar when anchoring and arming the alert.

Version 2.4.4

  • After the first installation of the app on a device all subsequent installations on other devices which are signed in to the same iCloud account will share the user id of the first device unless the user changed it. So the mirrorfunction is now ready to run out of the box.
  • Added a new option in the settings to use the last distance and perimeter radius when dropping anchor via the anchoring dialog.

Version 2.4.3

Improved mirroring and proximity alert handling:

  • A device can no longer be set to transmit while not anchored.
  • Sending a device to receive while the device you anchored with is not already transmitting will automatically the anchoring device to transmit, provided it has the proximity alert active.
  • Terminating the app for any reasons will now remove the device as active device from the server after 5 minutes.
  • The receiver will now also show the transmission time of the data if it differs from the receiving time.
  • General improvements on communication stability and recovery.

Please note that when anchoring with two devices at the same time, the proximity alert must be deactivated on the second device.

Other changes:

  • Automatic screen locking can now be disabled in the settings.

Version 2.4.2

  • Fixed a problem with the bearing and distance window not updating after anchoring.
  • Fixed a problem with user ids with special characters crashing the app.
  • When setting a device as mirror receiver, the screen will be automatically locked.

Version 2.4.1

  • Fixed a problem with not updating the status bar and buttons when anchoring by touching a favorite anchoring place.
  • Fixed a vanishing anchoring symbol in Google Maps.
  • Added an ahead vector for the boat heading to make it easier to hit a favorite. Length of the vector is 250 m fixed and it is visible only in combination with the directional ship icon and while NOT at anchor.

Version 2.4

  • Reworked the mirroring system. Receiver will now receive data immediately as soon as transmitter sends it without the need to polling it. Also the track plot on the receiver is more detailed. You might have to reregister your id if you registered it recently.
  • Added a new experimental feature: Proximity alert. If two boats which are using Anchor Sentry are anchoring close to eachother they are alerted if they come too close to each other because of dragging anchors. See the communication settings for an explanation how it works.
  • Reworked the help system. It is now local and does no longer requires an internet connection.
  • Added a low battery alert.
  • Added a alert test to check the sound volume.
  • Position data can now be acquired from a NMEA datasource instead of the built in GPS.
  • Some minor UI fixes and improvement.

Version 2.3.5


  • Fixed some UI problems in Darkmode.
  • Compass line now checks device orientation to display correctly.

Version 2.3.4


  • Switched to Navionics SDK Version 1.1.8 in order to faciliate Navionics' new license system.
  • Your current Navionics subscription can now be shown in Settings->Navionics status.

Version 2.3.3


  • Fixed a possible problem with iOS 14 and the depth display.
  • Added a visual display for the current warning perimeter.

Version 2.3.2


  • Reverted to an older version of an included external library as the newest one seems to cause random crashes with this app.

Version 2.3.1


  • Your favorite anchoring places and exclusion zones can now be exported to your iCloudDrive and also imported from there again. Please be aware that importing into a device with exisiting places or zones might result in duplicates.
    You will find the export/import functions at Settings/Administration.
  • NMEA server interface now also provides the UDP protocol

Version 2.2.3


  • Fixed a crash when exclusion zones without name were displayed on Google Maps.

Version 2.2.2


  • Changed appname from Anchorwatch to Anchor Sentry to avoid confusion with similiar named apps.

Version 2.2.1


  • Increased size of toolbar icons. Toolbar can now be shown above or below the map. See Settings.
  • Zoom buttons can be moved to the left map border or get hidden completely. See Settings.
  • New option to apply current gps accuracy to the alert radius before triggering alert. Ex.: Radius is 50m, current gps accuracy is 5m. Alert will be triggered when boat is more than 55m from anchor.
  • Reverted to fixed compass rose and moving bearing line.
  • Exclusion zones show their id and name on the map.
  • Selecting an stored anchoring place on the map (orange anchor) will now also offer the option to drop anchor exactly their.


  • Fixes for compatibility with iOS 13.2
  • Fixed a crash when increasing the number of distance circles.
  • Fixed a crash when selecting a stored anchoring place.

Version 2.2


  • Anchoring places can now be saved and will show on the map as an orange anchoring symbol:
    Add to favorites
    Use the
    Add to favorites
    button on the right side while anchored to save the position.

    Tapping the anchorplace icon gives you information and allows you delete it. Not available if the current anchor position overlays the anchorplace.

    You have access to all saved places from the Setup menuitem Anchoring places. There you can edit and delete saved places.

  • Implemented a version history. This one.
  • Map will now center on ship (or anchor while anchored) when app becomes active from background.


  • Fixed some missing English translations.
  • Fixed a problem with moving the distance circles to the ship while at anchor. Circles will now stay on the ship until switched back.