Anchor Watch

Anchor Watch

“Anchor Watch” uses the GPS on your smart phone to monitor your boat‘s position. If the boat moves outside of set limits, the program will alert you immediately. Alerts include phone calls, sound, vibration alerts, pop ups or email.

A ship adrift

There are no more sleepless nights when you worry about whether your boat is dragging or not. Keep the phone next to where you are sleeping and a quick glance will assure you that all is ok.

If the boat drags out of the predefined areas, it will alert you in any way you decide. Flashing text, sounding alarm or even call to another phone.

Anchor Alert

Anchor Watch sophisticated filtering allows for GPS errors, which can occur every now and then. The settings panel is fully customized allowing a number of different alarm types.

Of course it fully supports iOS4 and runs in the background too (but you can tell it to conserve battery and update only in foreground) which allows you to pursue other activities on your phone while Anchor Watch is on guard.

Anchor Watch is available for iPhone and iPad. Both versions are device specific implementations so you will get the best experience out of every device.


Anchor Watch Settings



75 comments on “Anchor Watch
  1. Tom says:

    Just got the Anchor Drag app and have been messing arround with it in the garden… looks good thanks. Got some comments if you want:

    Can you turn off the Google backgrond?
    The reason for this I like to charter overseas and tend to have data roaming off so that I do not run up lots of extra phone charges, and would want to be sure that google map was not using up lots of dosh.

    Can you have a numerical value on the range in Meters and the option to set the range in meters. I think most people know how much chain they have down.

    Also setting the anchor location as you drop anchor is not practical. It is somthing I would normally do later (Tpically on the GPS) but you app should be alot easier. So it would be nice to move the anchor location as if you drop later you may well already be at the extremity of your range.

    When I set it then come out of the app and back in it is unset! does this mean it is not set when I leave…. looks like another trip up the garden to find out.

    These sorts of changes make is a useful app. But thanks for doing it. Tom

    • lukassen says:

      Hi Tom,

      Of course you can disable data roaming (Settings App->General->Network->Cellular Data = OFF). You will just get a grey screen instead of Google background, but the GPS will work just fine.

      As for numerical values, there is a new version awaiting Apple’s approval which (on popular user request) shows the anchor length as a number, and you can choose meter, feet or nautical miles (i know that’s quite a bit of chain :-).

      Moving the center location is something which we are thinking about, perhaps we can calculate the orientation from the trail and use that to determine how the ship is turning around the anchored position, I’ve some ideas but I need some sailing data (hence time to sail 🙂 to figure this one out.

      As for quitting the App, on a 3G or iPad it will kill the App so no monitoring, on a 3GS or iPhone4 running iOS4.x it will run in the background (eating up your battery unless you disabled this in the setting). Thanks for the comment, the offsetting is definitely something which will come in the near future.



      • Tom Bell says:

        Thanks for the update – Just read it as I have just got iPHONE 4 so it will run in back ground.

        An idea on the central location – can you display this as Lat/Long? then allow editing? Tom

      • lukassen says:


        There is a new version in the store since yesterday that allows you to set the anchor position simply by pointing at the screen. Doesn’t display the Lat/Long though. I’ll put that on the list



  2. Jacopo says:

    I downloaded anchor watch for ipad but i found no way to access the settings. How do you go to the relevant panel?

    • lukassen says:

      Just rotate the iPad 90 degrees to landscape mode 🙂

      • jacopo says:

        Thks. 😉
        Another question: when the boat drifts off, your app sends one and only one warning e-mail. To get a new message you have to switch off the app and start it over again. In other words Anchor Watch doesn’t send an e-mail every time the alarm resounds, but only the first time.
        On the contrary, I think it would be very useful to receive a new warning mail with the actual boat position every, let’s say, minute after the first mail. This way, if one is ashore & out of sight of the boat, one can follow via mail the movement of the yacht (and also be 100% sure that the first e-mail was not a mistake).
        Could you implement this?
        Great app, thanks again

      • lukassen says:

        Great idea!

        This should not be too difficult. Basically, as long you stay outside the circle, repeat the email every minute. I’ll look into it.



  3. jacopo says:

    Hi Chris. another 2 c.

    In this case, it would be very nice for a sailor to be able to selectively block the download of Google Earth datas from within the app (without going into App->General->Network->Cellular Data), while allowing the app to send an email using the 3G connection. Reason: when you are abroad you probably don’t want to incur in roaming costs for G. Earth, but you still want the device to send the warning mail.

  4. Pat says:


    May be I’m missing the point, but two things make Anchor Watch useless on my iPhone 3G:

    – after one minute, my iPhone sleeps in (screen turns dark). Then Anchor Watch stops to monitor the position and it doesn’t alert me when leaving the circle.

    – when leaving and starting again the app, it “lifts the anchor”, i.e. it forgets the position recorded position. I suppose the same happens when receiving a phone call.

    Do I do something wrong?

    • lukassen says:


      for the first issue you are not running on connected power, I can override Apple’s guidelines and leave the screen on, but it would drain the battery in about 1-2 hours. For the second question, excellent suggestion, I just released Anchor Watch 2.0.0 to the AppStore which has a setting to allow you to do that (on a 3G)



  5. John Macfarlane says:

    love your App, I anchor a lotvin US San Juans and Canadian Gulf Islands, this is a brilliant App. Gotvone for my iPhone, one for my iPad and giftedconecto a friend! Have you talked to Navionics? They really need this, specially if it could be integrated. Either way it’s great, thank you.


    PS you got my first 5 star rating!

    • lukassen says:

      Thanks a lot,

      There’s an update in the works that will bring offline maps to Anchor Watch, however US charts will probably not be available on the first release. We are working on that.

      Best regards,


  6. Bernd Meyer says:


    fantastic app! no other anchor watch or geofencing app for the iphone can raise an automatic alarm without constantly sending enormous amounts of data to some external server web site. This is exactly what I’ve been looking for. Five stars, thanks!

    There is just one little bit of functionality that I think is missing: optional position update emails at regular timed intervals.

    My boat is normally on a swing mooring for the whole season. How do I know that anchorwatch is still running on my boat? My solar power has failed before, so after some time on the mooring I can’t be 100% sure that the system is still running. I would be sure, if the system would either allow me to remotely query the boat position (via email / sms, but I think the iOS restrictions make this impossible) or if it could be set to send position updates, say once per day. If no update arrives I would know something has gone wrong. Such updates would have to be infrequent (say, choice between every 1/12/24/72 hours) in order not to cause a large data volume.

    It would really let me sleep better!



    • lukassen says:


      It’s on the roadmap. We are first releasing an update that allows the usage of off-line maps (unfortunately the coverage and quality is limited, see
      Next on the list is periodic email. I don’t think it is very difficult to implement, but it will be difficult to test. I tend to use this phone 🙂

      It will be a free update.



      • Bernd Meyer says:

        Hi Chris,

        if testing is a problem, I’ll be happy to be enlisted as a beta-tester (i let anchor watch run on an old iphone, which i don’t use for anything else anymore).



      • lukassen says:

        Hi Bernd,

        That’s okay, I’ll manage with my company Windows Mobile Phone (the things I have endure for you guys 🙂
        I’ve been extremely busy lately with pushing out updates, but I’ll turn to this one soon.

        My design so far suggests:

        – add a toggle button in settings “repeat email alert [on/off]”
        – add a setting under the detailed settings stating “email repeat interval hh:mm >”
        – add a pickerview (as with the clock app) to set the time
        – when in alert after sending an email, setup a timer with the interval for the next (if needed)

        I’ll need some test cases like moving back in the anchor circle cancels the alert, as does changing the settings etc. There’ll be some corner cases to think about.



  7. Bernd Meyer says:

    Hi Chris,

    it may be that we misunderstood each other —- what you seem to be writing about is sending an anchor drag alert repeatedly instead of only once. I think this would be great, but what I meant in my originally posting was a different (and as simple feature): simply sending a position update every x hours.

    The main purpose of this would be to is to be sure that the system is still up and running while one is away from the boat even if there is no alert. Simply put: if I don’t receive an update every x hours i know the system has died. It would be even better if such an alert could include the battery level. (What has happened to me a couple of times before with similar kinds of installations is that for one reason or another my solar power failed, my phone and GPS didn’t get recharged and thus my anchor alert was defunct without me being aware of it).



    • lukassen says:


      I see, well that would be more like tracking by email not? (I guess I could also make an app for that 🙂

      In essence the behavior would be the same for ancher watch to be in an alert. I think that sending emails while not being in alert would be confusing to the users. Using manual anchor adjustment you should be able to create an alert situation quite easily.

      the good news is, i found out how to get the battery level and will try to include it.



  8. Bernd Meyer says:

    well, i don’t think it would be confusing, if there is a preference setting whether this happens or not.

    For example, if I had the option, I’d get a position report every 24 hours but only an anchor alarm would also call my phone (and send email).

    You are, of course, right that this a little bit like tracking. However, the purpose is quite different: I just want to be sure that the system is still up and running and has a valid GPS signal. In regards to this, even a “dead man switch” (just sending a regular email “i’m still alive and kicking”) would be good enough. Without active feedback, given how many components can fail on board (power, cables, aerial, water intrusion, the iPhone or the program itself, …) I cannot see how users can be sure that the system is still operational when off the vessel for extended periods of time.

    I’ve used tracking services for this purpose before (with geo-fencing happening on a web server, so that i can emulate an anchor alarm), but the problem with these is that they sent position updates at high frequencies. This costs loads of money (specifically when overseas) because it constantly uses data. The alternative is to track the position infrequently, and this is not safe.

    Another system that I’ve used previously had the ability to be queried from the shore by sending an SMS to it, to which it replied with position information. This was an excellent way to check that the system is up and running, but I believe this is beyond what you can do with the official iPhone SDK.

    What I’m suggesting is to constantly evaluate the position locally and send an instant alarm if drag happens, but to (optionally) send infrequent and thus cheap tracking data by email to make sure that all is still operating.

    Does this make sense?


    • lukassen says:


      Here’s a beta of what we are trying to do:

      Currently tracking your device at
      Position Lat 52.1537, Long 5.3723

      Battery Level: 45.0 percent (Draining)

      • Bernd Meyer says:

        Great! looks like what I had in mind. Can’t wait to see the new version!


        PS: would it be possible to include distance (and heading) to anchor in these “tracking” messages? I’m sure you have them available anyway?!

  9. Wayne says:

    Just downloaded. Great app looks like. Ipad sound doesnt work on alerts. Am i doing something wrong? All the iphone changes mentioned above, can you mke them available for ipad?

    • lukassen says:


      Yes just finished uploading new versions to Apple, both for iPhone and iPad. Sound works on my iPad, silly question, but did you perhaps mute the audio?



      • Wayne says:

        Not such a silly question after all. Forgot the new iOS changed the switch to a mute button. Thanks. Works great.

  10. lukassen says:

    @Bernd, heading and speed will be included if they are valid.

    On an iPhone 3G you will frequently get illegal values. (course 110, speed 1.94 knots) the new version will filter those out. I like testing on 3G, since if it works there, it is really snappy on a faster device. So no worries.

    The Lat/Long will become a clickable link to Google maps so if you receive your report on a PC or smartphone, you can really pinpoint the location. I’ve been tracking myself by email with this while running 🙂

  11. Bernd Meyer says:

    Hi Chris,

    just downloaded the latest release.

    Some great improvements, but I see that what we had discussed didn’t make it into this release. Just checking whether you have plans to include it into a subsequent release or whether you have decided to ditch it.

    The repeat alarms in the latest release only seem to work once an alarm has been raised, i.e. when the safety perimeter has been traversed.

    What I advocated is an additional (infrequent) regular position update while the gps location is *within* the safety perimeter, just to make sure that the system is still up and operational.

    With the features that are there currently, I have no way of making sure from a remote location that the system is still up and running all the time while the vessel is considered to be within a safe range. Not being able to ascertain whether the system is still operational while the boat is supposedly safe basically renders the system useless for long-term use.

    Are you planning to include some sort of dead-man-device like this in one of the future releases?



  12. Matt Walker says:

    Hi Chris,

    I downloaded your ap late last night (in bed) and I think I screwed up when it asked whether to allow GPS to use my current location, I selected “do not allow”. Is this why I cannot get it to work? How can I go back and select “allow”? If this is true, why is there a “do not allow” option that disables the ap?


  13. Matt Walker says:


    I am new to the Iphone as well. Thanks for the help! (turning on the GPS from settings) Working just fine now.


  14. Bjørn O says:

    Great app – have one question from Norway.
    Is it possible to include a course-deviation-alarm? When I anchor up front-in against a dock or a shore, I allways worry that my anchor will come loose and the boat will turn longside against the dock/shore. Could the app use the compass, and include an alarm that triggers upon selecable degrees of deviation?

    Kind regards BO

    • lukassen says:

      That is a great idea! I’ve been puzzling with this problem for some time. This would mean:

      – Upon lowering the anchor lock the angle of the device w.r.t. north (don’t move your device after that 🙂
      – Display an north pointing vector once locked
      – Display an actual vector once locked
      – Add a setting for course alert on/off (persistent, backward compatible)
      – Add a setting for course alert degrees (picker?)
      – Create a watcher that calculates the course drift and triggers an alert
      – Update the messaging to indicate the type of error

      There’s some work to do 🙂


      • Bjørn O says:

        Maybe a lot to do, but still very useful. It could be simplified GUI-vice, the only user-interaction needed is the screen for turning the function on. Using standard-library for alarms etc. You don’t need to display North or position/vectors or anything else really, Just put the phone down at the nightstand, press “Start monitoring” in the application and a predefined “max 10 degrees accepted deviation” (with an option to change degrees) and go to sleep 🙂

  15. axel says:

    hi chris,

    second night with 30+ kn of wind on anchor in malta. app works fine. just – i purchsed the offline maps and never got them.

    what can i do?


    my tip: night vision mode.

    • lukassen says:

      Hi Axel

      Good to hear it’s working fine. After unlocking the mapstore, you should be able to navigate through the openseamaps ( on the server. you can then click and download the maps you need.

      I’ll think about a night mode, maps are going to be tough i fear.



  16. Ozdemir Anil says:

    Dear C,
    My friend download your program. But he needs help about the language. Can you send us instructions in Dutsch.
    Thanks again.
    Many regards,

  17. lars dall says:

    need manual in english (or danish)

  18. Ian says:

    Hi Chris
    Do you have a guide on how to use the anchor app.
    A Youtube Film would be great. I have a iPhone 4.
    Thanks. Ian

  19. Don McLennan says:

    How about sending an SMS text message alert?

    • lukassen says:

      Yes that would be great, however Apple does not allow autonomous access to the SMS. I could set up a premium number and have the App fire off a dozen text messages. Which is why the user must press the “Send” button, rendering the function useless.

  20. Steve Wolfer says:

    Hi Chris, I just purchased the new iPad with IOS 6.0 (WiFi only) and will be using the Dual Electronics XGPS150A external gps. Will your app work with that operating system, and with the external gps?
    Thanks, Steve Wolfer

    • lukassen says:

      Hi Steve,

      I don’t know, since I don’t have that type of GPS. In general we support external GPS, but there could be a brand difference. I’ll email you a free code to try Anchor Watch, and would appreciate it if you could reply back here if it works. (and if it does perhaps in the App Store as well.

      Best regards


  21. Deep says:

    Hi Steve,

    Great program. I gave you a 5 star rating on the itunes store. I’m a captain of a dutch cruising sailing boat.

    Some little questions: Is it not bad for my iphone if the screen is on all the time?

    The version of my iphone (I looked it up in “about”) is 4.1. Does it mean the program will run in the background? If I put my anchor and exit the program and then go back in the program the anchor is up again! How does this work?

    Regards Deep

    • lukassen says:


      In general the screens can take the beating and the phone tends to die of dropping it rather than burn down 🙂 You can dim the brightness though. Your phone runs a 3 year old OS that does not support multitasking, you might have an iPhone3GS and you should be able to upgrade to iOS 6 but I fear it is a 3G or older which is not capable of doing so. Anchor Watch will gray out the multitasking switch if this is the case. This is also why the Anchor state is not remembered since the App cannot tell if you moved since the last time it ran. So for monitoring you must keep it running.



  22. Doug Montgomery says:


    Just downloaded the iPad version (HD)…I really like it so far. I’ve sent you an email, but thought posting here would be beneficial to others reading.

    I was looking for an option that would give me two major things

    1. When anchoring for the night, sleeping ashore in a tent or walking around a beach…I wanted an app that would signal me (SMS/Email/Phone & Audible) if the boat moved out of a predetermined area.

    2. Allow me to get updates on my vessel location.

    Your app seems to be the only one..or perfect one for this. For the audible portion, I’m attaching a VOX operated relay to my iPad headphone output…when the alarm sounds..this would trigger a relay that is attached to my horn! 🙂

    Now, I notice your description above states you can get phone call alerts..however I’m assuming that I don’t see that option since I’m using an iPad. However, I do have a MagicJack, and they have an IOS app that allows you to use your iPad/iPod as a PHONE!. Was wondering if you could allow Anchor watch to utilize this app to call my phone?

    Would be an awesome option..and at $19 a year for the MagicJack..and very economical option.



  23. Ed szol says:

    Is the proper use of the app to “drop anchor” on the app at the spot you actually drop the anchor, then let out the rode until anchor is set and then make the alarm circle just beyond that point on the alarm circle?

    • lukassen says:

      Hi Ed,

      It depends a bit, typically my usage is as you described, but I usually sail in very small craft. Other users use the offset mechanism or direct lat/long entry. All in all, the anchor should reflect the anchors position and the guard circle is proportional to length of chain you use.

      Hope this helps


  24. MICHEL BOURDON says:

    Very good application, I use it every day and 260 days a year. Could you just add a pop up to confirm when we ask to take off anchor because on iPhone, sometime when you take it you touch the anchor bouton and it would be better to annul the command.

    Thank you.

    Michel Bourdon.

    Yacht TEATA BLUE

    e.mail :

  25. Marko says:

    Hey lukassen, has anything changed regarding the possibility for your app to send SMS message? Could be useful when on the shore. Another way I was thinking about is some kind of a horn that would accept a signal from the headphones jack of the iphone.. And I think a proper horn (LOUD), not like those that are being sold on Amazon for couple of bucks…

  26. Marko says:

    I believe sms feature through this service costs 70 eur per month..

    • Joel Rutzen says:

      Marko, I believe that you get 9 or 10 free sms credits when you join MessageBird. After that, you can buy sms credits. They show you the different price levels depending on how many you buy. The minimum is 100 credits, I think. As far as I can tell, they do not expire unless you don’t send a message for 12 months. There is no monthly charge. As I haven’t actually dragged yet while out, I just passed my original 10 credits. I have been executing a test alarm each time before I leave the boat, and it worked great each time. So far no dragging this year though, which is a good thing! You just have to have internet on your Anchor Alarm device while you are off the boat with your phone. Also, I have my device connected to an external wireless speaker (I use SoundCast because it has longer range than Bluetooth). When the alarm goes off, it could be set to be quite loud. Mine is wireless, so I bring the speaker into my berth while sleeping, so that I don’t wake guests in other berths, but also allows me to hear the alarm when genset and air is making noise. The speaker could also be set outside and on full volume when you leave the boat. It wouldn’t be as loud as a horn, but it depends how far away you are from your vessel. Hope his helps, Joel

      Date: Mon, 18 Aug 2014 12:48:32 +0000 To:

    • lukassen says:

      It depends on how many you buy. You can send 100 SMS for 15 euro, or 10 for 1,5 and as Joel said, use the test mode to see if it works for you prior to making costs

  27. Rob Richardson says:

    Just downloaded Anchor Watch and it looks great. It is installed on a WiFi only iPad with a Bad Elf 1000 GPS and everything appears to be working fine.

    Is it possible to turn off the background images download from within the app? to minimise data charges. The iPad is connected to an in-boat Wifi 3G modem and is used for downloading weather data so I cannot turn off its access to the Internet.

    I checked the site and downloaded their iPad app which included an off-line world map of adequate quality for anchoring, but have not been able to link it to the Anchor Watch app. Also opened MapStore but this did not help me? I assume using an openseamap will over-ride the background image download?

    Cheers and thanks for a great product. By the way I sail in southeastern Australian waters.

    Rob Richardson

    • lukassen says:

      The idea was that you disable internet access indeed, we did not consider the use case where only Anchor Watch should not be connected to the internet. I’m not sure it can be done, but we will look into it. As for OpenSeaMap, the “Nautical Map” option offers the same functionality. Though the OpenSeaMap app caches slightly more data. Both OpenSeaMap and Anchor Watch cache tiles rather than downloading the entire map for offline usage.

      Hope that helps


      • Patrick says:

        Is it still so, that
        a) only a small part of the OpenSeaMaps are available for offline use and
        b) the offline resolution ist much worse then in the real OpenSeaMaps and competely useless when anchoring?
        My experience is based on the “Mediterranean” Maps (just tried again today).
        Or do I do something wrong?
        Other than that, I’m very happy with AnchorWatch.

      • lukassen says:


        for Mediterranean, I couldn’t agree more. What the App does is similar to navigating to: then under tools click download chart. The offline maps are fairly course grained. What you can do is use the “Nautical Chart” option which will download tiles on the fly (with high detail) and cache them on the device. This is more clumsy but will give you better resolution. It is the same approach that the openseamap App uses.

      • Patrick says:

        Hello Chris,

        Thank you for the advice about “Nautical maps”.

        I just tried that. There is no sea in the vicinity, so I tried to zoom out to see the whole europe and then zoom into an interesting area. I doesn’t work because the app resets the view to my actual GPS position every few seconds. Do I have to forbit Anchor Watch from using the GPS to prevent that, or do I do something wrong?

        Second question: is there an “easy” way to cache a whole region (e.g. 100 miles of coast, with enough details from each bay)?

        Third question: is there a way to know which places are cached and which not (a cache has usually a maximal size and older contents are deletete)?

        I think that an easy way to cache or save a region (e.g. 100×100 miles) would be a great addition to Achor Watch, almost as great as the possiblity to definine a non-circular anchor “circle” 🙂


  28. lukassen says:

    You are right, and we have been experimenting with that, but it is quite hard to get it right. So for now the method you have lined out is the only way, sorry about the inconvenience

  29. Hi,
    is there any possibility to change the radius of the safety circle?

  30. Bob Gurwicz says:

    Hi Chris,
    Where may I find instructions on using your App. I’ve played around a bit with it, but I’m not sure I have a good handle on whether I’m using this correctly. Also, the program says chain length, what if I am using a combination of chain and rope? I have loaded the app on a Google Nexus 7. Thanks in advance for your help. Bob

    • lukassen says:

      It’s the same, it calculates the distance between the position you were when you anchored, to the actual position. But I’m more interested how you loaded an iOS App on a Android device?

  31. Paul Fearnley says:

    How does the filter work, and what do the sliders do labelled “time from” and ” min. accuracy”?

    • lukassen says:

      It’s a hystresis loop to avoid outliers to cause false alarms. The screenshots are old, the slider used to set the radius, which can now be set with an increase and decrease button. I don’t see the text you mention.



  32. Michael O’Halloran says:

    iPhone 6s I have lost all sound. Volume up restart app restart phone still no sound. Love the app

    • lukassen says:


      It should be possible to ignore the mute switch by telling the phone to do so. Try going into your iOS settings: “General > Sounds > Ringer and Alerts” If ‘Change with Buttons’ is set to Off, then sounds will always be played at full volume.

      Sound alert settings can be tricky in iOS. Try going into the Settings->Notifications. Make sure it is “on” and the Alert style is set to “Alerts”. If this is set to “None” the sound will not be audiable.

      Let me know if this helps

      • Mike says:

        Thanks for the reply. I feel stupid as I had accidentally switched silent switch on.

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