# Anchor Sentry

> Anchor monitoring app for ships, alerting to anchor drag and perimeter breaches. (iPhone/iPad app by Michael Dieter Konz.)

- Source: https://appshunter.io/ios/app/anchor-sentry/id1422478182 (this page in markdown: same URL + `.md`)
- Developer: [Michael Dieter Konz](https://appshunter.io/developer/1422478181)
- Category: Navigation
- Price: $3.99
- Rating: 4.00/5 from 4 App Store ratings · 15 written reviews indexed
- Age rating: 4+
- Requires: iOS 12.0 · 96 MB
- Languages: American English, German (Germany)
- Released: 2018-08-08
- Data updated: 2026-08-24
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/anchor-sentry/id1422478182/reviews.md

## What is Anchor Sentry?

Anchor Sentry is an app to monitor the ship's position at anchor and inform the skipper when the anchor is dragging and thus the ship leaves the setup perimeter.

Features:
- Show current position on GoogleMaps map or Navionics map (To gain
access to Navionics maps from this application, users with an active Navionics
subscription in the Navionics Boating application must register with their Navionics
credentials)
- Distance circles to help finding a good anchor position
- Drop anchor by tapping on map or by position or by bearing and distance
- Can be used for anchoring with shore lines by watching the heading rather than the position
- Tracks can be saves as GPX file for later processing
- Option to set up prohibited zones which will trigger an alert when entered. These can be used indepent of the anchor state
- Runs in the background even while other apps are used
- Unique sync functionality which allows to pair two or more devices together to see the ships position even while out to shore for dinner
- Barograph function included
- Display real echo sounder data from a providing NMEA server
- Optional compass overlay to help finding the bearing to the anchor
- Option to show current position visible to friends and family on the Anchor Sentry website
- Proximity alert between ships both using Anchor Sentry. To get warned when your neighbours anchor is dragging.
- Automatic anchoring feature
- Display maximum swinging circle
- Save favorite anchoring places with pictures
- Several setup options to customize your app

## Key features

- Anchor drag and perimeter breach alerts
- Map display with Google Maps or Navionics
- Prohibited zone setup with alerts
- Background operation
- Multi-device sync functionality
- GPX track saving
- Favorite anchoring place saving

## Recent user reviews (10 of 15)

All indexed reviews: https://appshunter.io/ios/app/anchor-sentry/id1422478182/reviews.md

### 5/5 — Viele Einstellmöglichkeiten und absolut zuverlässig

*2026-05-24*

Nach diversen Apps endlich eine die überzeugt! Es sind diverse relevante Einstellungen möglich. Trotzdem übersichtlich. Und vor allem, sie ist zuverlässig.

### 5/5 — Mirroring

*2026-01-13*

I went through a few Anchor apps two of them so far gave up the bearing and then in Support and Anchor pro was talked about a lot online, but you have to do a prescription and then another prescription of telegram app. It’s ridiculous and it’s delayed. Anchor Century is working as advertised to your phone every few secondsI’m gonna rip the update that doesn’t run.

### 2/5 — Mirroring not working

*2025-06-06*

Despite several hours of trying to establish a remote monitoring capability using the mirroring feature, unfortunately the remote device would show the location of the transmitting device but would not trigger an alarm. I did get this to work once, but then had to unregistered and re- register the sending device each time otherwise the receiving device won’t alarm. Even after doin this it was still random as to whether the remote device would alarm. Works well as standalone anchor alarm! But mirroring is what I purchased the app to deliver. Maybe it works for others…?

### 3/5 — A bit buggy

*2023-11-13*

Have used this app for a couple of years. For some reason it has gotten buggy. Looses track of where I drop. Plus it has position lines zooming out of anchor circle all over the place.

**Developer response:** Erratic lines all over the space are an indication that there is a problem with the GPS signal. This can have many reasons, none of them the app can anything do about. GPS is a radio signal and as such can be disturbed. Even having the device resting close to a desktop computer can disturb GPS reception.

### 5/5 — Guter Ankeralarm

*2023-08-19*

Vor allem die Synchronisation auf ein zweites Gerät ist super praktisch. So hat man auch unterwegs an Land immer ein Auge auf das geliebte Bötchen 🙃

### 5/5 — Ohne nicht mehr

*2023-06-18*

Ich benutze die App seit ein paar Jahren. Das erspart mit nachts die stromfressenden Instrumente mitlaufen zu lassen. Die Position wird sehr gut aufgezeichnet, der Alarm funktioniert und so kann ich vor Anker ruhig schlafen. Einzig bei der Kopplung hat das Handy an Bord nicht korrekt aufgezeichnet und mit einem Fehlalarm etwas in Hektik gestürzt.

### 5/5 — Der beste Ankeralarm, den ich an Bord hatte

*2023-04-26*

Diese App macht alles das, was man sich als verantwortungsvoller Skipper wünscht. Seit zwei Saisons im Einsatz - letztes Jahr 4 Monate Ostsee mit sehr viel Ankern und immer ruhig geschlafen. Herzlichen Dank an den Entwickler, bleiben sie dran.

### 5/5 — Super App und super Support

*2023-04-14*

Ich habe es geschafft mein iPad und mein IPhone bei der Spiegelung auszutricksen. Auf Nachfrage beim Support wurde das Problem sofort und mit viel persönlichem Einsatz behoben. Super, so wünscht man sich das. 
Die App mit der enthaltenen Funktionalität begeistert und tut genau das was wir Skipper brauchen. 👍

### 5/5 — Prima Tool

*2022-12-07*

Tolle Funktionen wie z.B. Weiterleiten der Position vom Boot auf das mitgeführte Handy an Land), kreisförmige Überwachung um Anker plus zusätzliche zu überwachende Bereiche mit beliebigen Konturen.
Sehr schneller, kompetenter Support.

### 3/5 — Mostly works

*2022-04-07*

After using for about a week, I had a false alarm one night. No big deal, make the radius a little bigger and go back to sleep. Except due to some bug the alarm would not shut off. Make the radius huge, turn off the alarm button, nothing worked. So I force quit and reopened the app. Apparently the app doesn’t save your anchor position or track data, so now I have no idea if I’m actually dragging. The bug is unfortunate but tolerable, but throwing away my anchor position completely makes the app worthless in the middle of the night. 

Only supports metric, so you have to convert in your head if you use feet.

**Developer response:** You can specify in the settings if you want to keep anchoring position and track. The default value is no. Given you comment I will change this to yes.

## Frequently asked questions about Anchor Sentry

### What is Anchor Sentry?

Anchor Sentry is a navigation app designed to monitor your ship's position while anchored. It alerts you if the anchor drags or if the vessel moves outside a pre-defined perimeter, ensuring your safety at sea.

### How does Anchor Sentry monitor anchor position?

The app uses your device's GPS to track the ship's current position on a map. It allows you to set distance circles and prohibited zones, triggering alerts if the vessel deviates from the set anchor position.

### Can Anchor Sentry be used with Navionics maps?

Yes, Anchor Sentry can display Navionics maps. Users with an active Navionics subscription in the Navionics Boating app can register with their Navionics credentials to access these maps within Anchor Sentry.

### Does Anchor Sentry work in the background?

Yes, Anchor Sentry is designed to run in the background, allowing you to use other apps on your device while still receiving continuous monitoring and alerts for your anchored vessel.

### What is the cost of Anchor Sentry?

Anchor Sentry is a paid application, priced at $3.99. This one-time purchase provides access to all its features for monitoring your ship's anchor position.

### Is Anchor Sentry suitable for all ages?

Anchor Sentry has an age rating of 4+, making it suitable for younger users under supervision. Its primary users are experienced boaters who require advanced navigation and safety features.

### How often is Anchor Sentry updated?

The latest version of Anchor Sentry is 2.9, last updated on March 12, 2026. While specific update frequency isn't detailed, this indicates ongoing development and support for the application.

### Can Anchor Sentry alert me to nearby ships dragging anchor?

Yes, Anchor Sentry offers a proximity alert feature for ships also using the app. This allows you to be warned if a neighboring vessel's anchor is dragging, enhancing overall safety in anchorages.

## Version history (last 5 releases)

### 2.11.4 — 2026-08-06

- Fixed rare crashes related to Google Maps and NMEA connections
- Fixed a possible app freeze when returning from the background
- Fixed the position accuracy filter incorrectly applying while under way instead of only at anchor
- Fixed the mirroring/proxy status occasionally showing as stale
- NMEA position input is now more reliable: connects properly when switched on mid-session, and falls back to GPS automatically if no data arrives
- Frozen GPS positions are now detected and recovered from much faster while under way, with a clear on-screen warning
- New setting: automatically prefer NMEA position while under way, with automatic GPS fallback
- New: upload the system log and recorded track directly to support from the log screen, for faster help with problems

### 2.11.3 — 2026-07-11

- Fixed the alert and anchor state shown on the mirroring/proxy server sometimes getting stuck after an alarm was acknowledged, even though the boat was no longer in an alarm condition. The current state is now sent immediately when an alarm ends or transmission is stopped, and is repeated on every transmission instead of only when it changes locally, so a single lost update can no longer leave the server out of sync permanently.
- Long-tapping a saved anchor place on the map now offers "Show Picture(s)" (if any are saved for that place) and "Edit". Pictures open directly in a new, simple full-screen viewer with the picture's description shown underneath, without going through the place editor.
- Fixed a possible app hang at startup. Navionics initialization is no longer done synchronously during app startup, and a redundant, near-immediate rebuild of the Navionics map screen right after launch has been removed.

### 2.11.2 — 2026-07-06

- Improved import/export compatibility for exclusion zones after the Posidonia changes and fixed imports of exports that contain no place images.
- Fixed a possible crash when drawing map overlays such as distance circles and tracks. All positions and radii are now validated before they are passed to the map.
- Fixed a memory leak that made the distance circles consume more and more memory with every position update.
- Distance and radius inputs in the anchor dialog are now limited to their valid range.
- Track drawing on the map was moved completely to the main thread to prevent rare, sporadic crashes.
- Fixed a possible crash on iOS 18 when a dialog was presented while another dialog was still opening or closing. Dialogs now wait until the previous one has finished instead of being lost or crashing the app.
- The alarm circle, shore circle, anchor and anchor places can now be grabbed on the map at any zoom level. The touch tolerance scales with the zoom level instead of being a fixed distance in meters.

### 2.11.1 — 2026-06-24

- Restored the warning dialog when location permission is insufficient, for example when it is not set to "Always".
- Added an optional position accuracy filter that ignores positions above a configurable accuracy limit and can warn about poor GPS reception.
- Stopping a triggered anchor alarm is now more reliable. When an alarm is acknowledged from the notification, it will not immediately start again while the boat is still outside the alarm circle. A new alarm can only be triggered after the position was back in the safe area first.

### 2.11 — 2026-06-03

- Added a new optional setting Show picker in dialog to choose between the previous in-cell pickers scrolling to change values in the settings and a larger picker dialog.
- Added dedicated position filter settings (master filter, speed filter, distance filter, distance threshold and time delay) in a separate filter settings page.
- Updated position processing to use the new filter options for speed and distance jump handling.
- Added Posidonia support in exclusion zones: Posidonia polygons can now be downloaded from Spanish authority data for the currently visible sea area and stored as zones.
- Posidonia zones are shown on the map for orientation but do not trigger alarms.
- Mirroring: Fixed a connection recovery issue when switching from onboard Wi-Fi to cellular data (e.g. LTE). The receiver now reconnects the WebSocket link more reliably.
- Proximity alert/mirroring: When transmission is stopped while the server connection remains active for the proximity alert, the connection is now kept in proxy mode correctly and no longer restarts normal transmitting after a later reconnect.

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## More apps by Michael Dieter Konz

- [Skippers Log](https://appshunter.io/ios/app/skippers-log/id1489815914)

All apps by Michael Dieter Konz: https://appshunter.io/developer/1422478181

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-24.*