Anchor Alert

What people are saying about Anchor Alert...

  • "Other drag alarm apps have not been successful and my Garmin GPS is hard to set and has proved unreliable. Your app certainly gets my vote! ... We had 20+ kts of wind and rising when the alarm went off. Spotted we were dragging at an alarming speed towards the South breakwater at Portimao, managed to start engine and get to safety but I think without the app we would have hit it or run aground near it. So extra special thanks for producing such an excellent app that works so well."- Nigel Heaton
  • "Saved my bacon! I used this app sailing in the San Juans last summer. I am a fairly novice and paranoid sailor, but using this app allowed us to have an amazing week. Using this app we were able to anchor in some very tight conditions in weather. There was one night where the app detected us dragging the anchor in a tight anchorage with other boats. Without this app, our sailing trip would have: a) not been possible, or b) been disastrous. Thanks to the folks that developed smart phones and apps!" - Erik Gerking
  • "Must have for cruisers! You must have this if you anchor your boat and can't stay on deck to be sure you stay put. Sleep soundly or go ashore for the day and know the boat is where you put it." - Daniel Otte
  • "Remarkable, The most realistic and effective app on Android" - Pierre Lavergne

What is Anchor Alert?

Anchor Alert is an advanced anchor alarm application from SlimJiM Software developed exclusively for Android. Anchor Alert was the first anchor alarm available for Android and still leads the rest in terms of features and reliability.

It features point and click anchor projection using the phone's built-in GPS and compass and allows setting of an exclusion area and optional slack zone. Together with the audible and haptic (vibration) alerts and support for running as a background task which allows the phone's GPS to sleep to save power, Anchor Alert is the world's most advanced smart-phone based anchor alarm.

Anchor Alert is only available on the Google Play store.

Read on to learn about some of the advanced features of this application and some of the other uses it can be put to...

Please note: Due to the use of some advanced functions only available in newer releases of Android, Anchor Alert is not available for versions earlier than 4.0. If you are stuck on an older version of Android and wish to use Anchor Alert you should contact your carrier about an upgrade.

Main Features of Anchor Alert:

Projecting the Anchor Position.

Unlike other anchor alarms, Anchor Alert allows you to project an anchor position in any direction and by any distance you want by simple point and click.

Anchor Alert uses Android's magnetic declination tables to automatically correct the phone's built-in compass for local magnetic differences so that an accurate anchor position can be calculated at any time and at any position on the globe. These magnetic declination tables are updated as required with the Android system so they will always remain as up to date as your phone.

Exclusion Angle and Slack Zone.

Anchor Alert allows any sector of the anchor circle to be excluded from the allowed swing area and if your vessel drifts into it, an alarm will be triggered.

This may be useful when you find the need to anchor your vessel close to land for more protection, close to another vessel that is moored to a buoy, or when anchored in a steady wind and you want to know when the wind changes. The exclusion area can be input with precision from the application preferences or with ease by touch and drag accessible by long-pressing on the centre of the screen.

You may also find at times that you wish to define a slack zone within the exclusion area. For example, when anchored in a bay where the vessel might swing around 180 degrees from it's original position due to tidal changes but you may only wish to be alerted if the anchor is likely to drag and not when the vessel has just wandered over the anchor position at slack tide. Anchor Alert allows this too. By setting the Slack Zone option and independently changing both the distance to anchor and the drift distance, any size slack area may be set around the anchor position.

Advanced Features:

Night Mode

Anchor Alert also has a night mode that dims the screen and changes the colour scheme so you don't lose your night vision.

Background Monitoring

Anchor Alert is designed to take full advantage of Android's multi-tasking ability. It is capable of monitoring the anchor position while running as a background task and allows you to use your device for other things such as checking your email or taking a call. No other smart-phone based anchor alarm can do that!

Metric or Imperial

Prefer to use feet? Or do you work better with the metric system?

No problem. Anchor Alert supports both metric and imperial measurements, just select your preference from the menu and it's all taken care of.

Multiple Alarm Options

Anchor Alert supports audio and vibration alert options and a visible alert dialog is also displayed through which you can cancel or snooze the alarm for a period that you define.

Low Battery Warning

Anchor Alert can also inform you if your battery is getting low. By selecting the low battery alert in the application settings a visual notification with optional audio and vibration alerts will be triggered to alert you that the battery is running down. Once at 15% power, then again at 10% and at every change from 5% and below.

Security and Privacy

Anchor Alert takes your security and privacy seriously too, the location data used in historic traces is relative to the anchor point only and no personal data whatsoever is collected or stored.

Other Uses of Anchor Alert:

Take Me To...

Set the exclusion area start position to 190 degrees and set the scope to 340, set the anchor position to however far away your target is, say 30,000 metres (30kM) or 100,000 feet (19 miles), from your current position, point the phone in the direction you wish to travel and press OK to set anchor. You can then use Anchor Alert as a guide to your location, stray too far off course and you'll get an alert, the alert area also gets smaller the closer you get to your desired location (the anchor position) so you need never be too far off course. Make sure anchor tracking is enabled too and let Anchor Alert guide you both magnetically and by your phone's GPS.

Dude, where's my boat? - (Remembering a Location)

Before going walkabout in an unfamiliar location, and after safely mooring your boat of course, set the anchor distance to 0 and anchor your phone at it's current position, the anchor will now be your point of reference. Now set the drift distance to the area you wish to cover, make sure Anchor Tracking is on in the preferences and take the phone with you. Anchor Alert will show you in which direction and how far away your anchored location is and can guide you back, useful if you often forget where you left your boat / car / significant other!

Additional Information

Help and Support

Anchor Alert comes with a built-in user guide and help section accessible from the main menu, you will also receive free technical support by email for the life of your purchase. See About SlimJiM for contact details.

Further Development

Anchor Alert is under active development, when you buy you will automatically receive all upgrades as soon as they are released and at zero extra cost. You will also have the chance to participate in the development of Anchor Alert and have your say as to what features should be integrated in future releases, an example of which is the night-mode feature that was added in version 1.3.2 in response to a user request. Although there is no guarantee that all such feature requests can or will be implemented, where possible a detailed rationale for the decision to include or exclude a feature will usually be given, now we can't say fairer than that!


Special thanks to "The BigLovin' Munky" for initial testing and feedback.

© 2010 - 2021 Simon Morgan, SlimJiM Software.