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Old 23-07-2021, 12:15   #1
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Anchor alarm apps - a comprehensive survey

When somebody asks on a forum which anchor alarm is best, the usual answer is Anchor Alarm, or Anchor Alarm!, or Anchor Watch... It is often quite funny, actually. Given that there are many alarms with these names, one is not any wiser afterwards.

So, in an effort to change that, I have done a survey of anchor alarms for iOS and Android and put all this in a long chart where I just list the features. A good number of them I have verified myself, but I am not done yet completely.

I am not giving any advice as to which alarm is the best one, but I give an option on which features I believe to be important.

Here is the link: https://trimaran-san.de/anchor-alarm-apps-overview/

Feedback always appreciated.

Cheers, Mathias
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Old 23-07-2021, 12:48   #2
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Re: Anchor alarm apps - a comprehensive survey

Very useful Mathias . I am sure those who use a particular app will provide some feedback.

My only comment is when positioning the anchor rather than "chain length plus vessel length" it would be be more appropriate to substitute "rode length plus the distance between the bow and the phone/tablet (or GPS aerial)". This will give the correct anchor distance assuming the rode is reasonably tight.
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Old 23-07-2021, 16:11   #3
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Re: Anchor alarm apps - a comprehensive survey

Quote:
Originally Posted by noelex 77 View Post
Very useful Mathias . I am sure those who use a particular app will provide some feedback.

My only comment is when positioning the anchor rather than "chain length plus vessel length" it would be be more appropriate to substitute "rode length plus the distance between the bow and the phone/tablet (or GPS aerial)". This will give the correct anchor distance assuming the rode is reasonably tight.
Thanks, and yes, you are right of course. If the anchorage is not crowded, I usually add some slack, but you are right!
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Old 23-07-2021, 16:43   #4
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Re: Anchor alarm apps - a comprehensive survey

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Originally Posted by MathiasW View Post
Feedback always appreciated.

Might I give a little feedback on the page itself?

I had to search hard for your chart.


The links are hard to identify. Just making them bold text is sub-optimal, especially when you also use the same bold characters for emphasis on non-link text.
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Old 23-07-2021, 16:47   #5
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Re: Anchor alarm apps - a comprehensive survey

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Might I give a little feedback on the page itself?

I had to search hard for your chart.


The links are hard to identify. Just making them bold text is sub-optimal, especially when you also use the same bold characters for emphasis non non-link text.
Ah, ok, many thanks. I will use a different colour then. On my browser it looks ok, but thanks for the feedback!
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Old 24-07-2021, 09:04   #6
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Re: Anchor alarm apps - a comprehensive survey

Quote:
Originally Posted by noelex 77 View Post
Very useful Mathias . I am sure those who use a particular app will provide some feedback.

My comment is when positioning the anchor rather than "chain length plus vessel length" it would be be more appropriate to substitute "rode length plus the distance between the bow and the phone/tablet (or GPS aerial)". This will give the correct anchor distance assuming the rode is reasonably tight.

Just do the math, it's not that hard :-)

Seriously, my main complaint with the two or three anchor alarms I've used (sorry I can't remember which ones), is false alarms. Every one of them woke me up in the middle of the night when the boat had not moved at all. So I tried setting the alarm at home, and while I slept the bed must have drifted a hundred meters, and the alarm faithfully woke me up in time to avoid a disaster. Note that the phone was plugged into the charger at all times.
The problem has to be intermittent GPS location data in the phone. This was with two different Samsung phones. Need to try it on my wife's iPhone.
Another very strange issue is that I simply could not turn off the app! I had to actually remove the phone's battery to stop it.
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Old 24-07-2021, 09:29   #7
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Re: Anchor alarm apps - a comprehensive survey

I prefer the anchor watch feature on our Watchmate AIS. Very low power consumption and the AIS is on always anyway. The screen at a glance shows where we are on our circle and where we have been no matter how long we are at anchor. We have pads and smart phones but all need charging and are used for other things. I consider the apps a back-up band-aid. The Watchmate is purpose built and never walks away. Fringe benefit is our designated fleet friends can find us easily.
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Old 24-07-2021, 09:45   #8
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Re: Anchor alarm apps - a comprehensive survey

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So I tried setting the alarm at home, and while I slept the bed must have drifted a hundred meters, and the alarm faithfully woke me up in time to avoid a disaster.
The most likely cause is a poor GPS signal. For an anchor alarm you need a very accurate GPS signal free of multi-path and other distortion.

An external aerial with a clear view of the sky will produce a significant improvement and is essential if you want to set a tight radius without false alarms.

Even on a boat many people have this issue as they depend on the phones GPS reciever mounted below decks. This will work, and is better than nothing, but you need a wide alarm radius to avoid false possitive alerts. In some anchorages a wide alarm radius is fine, but not all.
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Old 24-07-2021, 10:08   #9
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Re: Anchor alarm apps - a comprehensive survey

Quote:
Originally Posted by noelex 77 View Post
The most likely cause is a poor GPS signal. For an anchor alarm you need a very accurate GPS signal fee of multi-path and other distortion.

An external aerial with a clear view of the sky will produce a significant improvement and is essential if you want to set a tight radius without false alarms.

Even on a boat many people have this issue as they depend on the phones GPS reciever mounted below decks. This will work, and is better than nothing, but you need a wide alarm radius to avoid false possitive alerts. In some anchorages a wide alarm radius is fine, but not all.
Also, I guess some cheap android phones will have also cheaper and thus poorer GPS receivers built in.
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Old 24-07-2021, 11:21   #10
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Re: Anchor alarm apps - a comprehensive survey

My issue is with Anchor Alarm is when I get a phone call the alarm goes off in the phone. Tried making gps range different and still does it. Hang up phone and alarm goes off.
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Old 24-07-2021, 12:02   #11
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Re: Anchor alarm apps - a comprehensive survey

I use the built in anchor alarm on my Garmin chart plotter, it works great!

It even figures out where the anchor is and uses that as the center point.

Has worked well every time I've used it.

Apollo Wayne
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Old 24-07-2021, 12:39   #12
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Re: Anchor alarm apps - a comprehensive survey

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My issue is with Anchor Alarm is when I get a phone call the alarm goes off in the phone. Tried making gps range different and still does it. Hang up phone and alarm goes off.
Same here. I usually disable the alarm for the time of the phone call.
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Old 24-07-2021, 12:42   #13
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Re: Anchor alarm apps - a comprehensive survey

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Originally Posted by waterman46 View Post
Just do the math, it's not that hard :-)

Seriously, my main complaint with the two or three anchor alarms I've used (sorry I can't remember which ones), is false alarms. Every one of them woke me up in the middle of the night when the boat had not moved at all. So I tried setting the alarm at home, and while I slept the bed must have drifted a hundred meters, and the alarm faithfully woke me up in time to avoid a disaster. Note that the phone was plugged into the charger at all times.
The problem has to be intermittent GPS location data in the phone. This was with two different Samsung phones. Need to try it on my wife's iPhone.
Another very strange issue is that I simply could not turn off the app! I had to actually remove the phone's battery to stop it.
Poor GPS signal as was mentioned before. I leave my phone where it can see the sky, even though that is not close to my bed / ear. If there is a lot of wind or other noise, which will make it difficult to hear the alarm, I use an external loudspeaker connected via BT to the phone. That one will wake up anybody. Of course, it needs to be plugged into power as well...
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Old 24-07-2021, 13:09   #14
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Re: Anchor alarm apps - a comprehensive survey

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Poor GPS signal as was mentioned before. I leave my phone where it can see the sky, even though that is not close to my bed / ear.
A GPS that can see the sky will help, but for the ideal anchor alarm the GPS needs an uninterrupted (or as near to this as possible) view of the sky. This requires an external GPS aerial. The anchor alarm will work without this, but you need to set a larger alarm radius and/or accept false positives.

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Of course, it needs to be plugged into power as well...
It is important that the battery does not run flat, but some anchor apps caution against leaving devices plugged into power. The concern is that when connected to power the device may perform a system memory reset, which can disable all apps.
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Old 24-07-2021, 13:15   #15
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Re: Anchor alarm apps - a comprehensive survey

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A GPS that can see the sky will help, but for the ideal anchor alarm the GPS needs an uninterrupted view of the sky. This requires an external GPS aerial. The anchor alarm will work without this, but you need to set a larger alarm radius.
Yes, that is generally what I do.

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It is important that the battery does not run flat, but some anchor apps caution against leaving devices plugged into power. The concern is that when connected to power the device may perform a system memory reset, which can disable all apps.
Yes, indeed, some claim that and I am sure it has happened. I have the iPhone always plugged in and have not seen that in 2 years. But one can reduce the odds of this happening by using two phones of different make as alarms.
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