What is your favorite anchor alarm app

[Davidasailor26]

I used Anchor Pro on iOS for a while, but it was just ok. Lately I’ve switched to AquaMaps built in anchor alarm. I subscribe to AquaMaps anyway and it seems like a full featured alarm that works just the way I want.

Hey guys
It is a long time since you discussed this issue. Sometimes, even with a good heavy anchor and proper anchoring techniques, I never feel entirely safe to sleep overnight w/out checking a few times if I am still in the same position. Any app that you will use will refer to the position of your boat and not the anchor. Using the Raymarine system is heavy on batteries.
Recently, I found a system (From Europe) that connects an anchor to the floating buoy above the anchor. If the anchor moves, then the buoy moves. It has a springing mechanism to compensate for tides up to 5 m on the 10 m depth. It uses a dedicated transmitter and receiver system based on LoRa, so you do not rely on your cellphone. If the anchor moves within a 5 m radius (geofencing), an alert is sent to the receiver on board, letting you know that you are dragging. Looks good, but the price is around EUR 1000 and there is a 3 m waiting time for delivery.
Few years ago I was thinking about putting together something like this, planning to use parts readily available on the market (mainly Alibaba). An extendable cloth line was converted into the link between the buoy and anchor. Antitheft devices/trackers were checked. Most of them are good at tracking stolen devices (will show you the town in Nigeria where your car is taken apart) but not very good at geo-fencing. I wanted to have an alert in case the tracker moved, say, outside a 10 m radius. Most will work only with a cellphone and will need a SIM card. On the water, we do not always have a cellular network. LoRa could be the solution, but how to get the alert signal out of the tracker on the buoy to the receiver on board?
Recently, I found a dog training collar that sends a mild shock to the dog's collar if the animal moves outside of the set geofence. Now I'm looking at how to get the shock signal converted into an alert that could be sent to the receiver on board. The interesting part is that the whole system will cost only CAD 200 if Alibaba comes to the rescue. And an additional advantage: if the anchor is stuck at the bottom, I will have a tripping line!/ik

Interesting idea. You could put an arduino or Pi Pico on the boat as a LoRa receiver, with a buzzer as an alarm and a couple buttons to set and cancel the alarm. That part would probably be pretty simple and cheap. The harder part might be keeping the anchor end powered and waterproof. In crowded anchorages it also would get involved in the borderline religious debates over whether using a tripling is allowable etiquette.

 

[Project_Mayhem]

THe app with the most humorous name that I've seen is called "Drag Queen"

 

[Ward H]

THe app with the most humorous name that I've seen is called "Drag Queen"

My ex asked to use my phone once when we were anchored out.
I had some explaining to do when she saw that app name.

 

[JBP-PA]

would inevitably forget to cancel the watch before raising the anchor and had to endure the alert screeching at me until I was in safe water.

I'm glad I'm not the only one who does that

 

[Bibicu]

Good to know when using Anchor Alarms

GPS Reliability
Accurate monitoring depends on the quality of the device’s GPS signal. Even when the boat is stationary, small variations in satellite accuracy can cause the displayed position to shift slightly on the map. This behavior is normal and does not indicate that the anchor has moved.

• Place the phone where it has a clear view of the sky — near a window or outside the cabin.
• Keep the device powered and connected; background restrictions or battery savers can pause GPS updates.
• Wait for the GPS accuracy to stabilize before setting the anchor position.
  
  Tip: Some devices reduce location accuracy when the screen is off. You can prevent this by excluding the app from battery optimization or keeping the display dimmed while monitoring.

GPS Accuracy
GPS accuracy varies with signal conditions and device quality. On most modern phones, accuracy is typically within 3–5 meters (10–15 feet) in open areas, but it can drop to 20–50 meters (65–165 feet) when the sky view is obstructed by cabins, masts, or terrain. Even when stationary, the reported position may drift slightly on the map — this is normal and does not mean the anchor has moved. For best results, wait for the GPS accuracy to stabilize below 10 meters before setting the anchor position.

Anchor Position
It is impossible to determine the exact position of the anchor. The accuracy of the anchor position depends on when and where it is set. If the position is recorded before the anchor is fully set, or if the anchor drags slightly after setting, the stored reference point will be offset. This can cause the displayed swing circle to appear shifted even when the anchor is holding correctly.
When standing over the anchor to mark its position, the phone’s GPS may still have a few meters of drift, and the anchor itself can move slightly as the chain tightens.
The bearing to the anchor should be used only as a rough indication. Most phone compasses are not that accurate, which can make the displayed direction unreliable. For accurate heading information, use the boat’s magnetic or electronic compass instead.

Conclusion
The size of the security circle should be determined by the anchor chain length, water depth plus freeboard, and the distance between the GPS antenna and the bow. An additional allowance should be added to account for the normal stretch and catenary of the anchor chain, and GPS and position inaccuracies — typically 5 to 15% of the total chain length, with a minimum of 30 feet (≈10 meters). If the circle is too small, normal boat movement can trigger false alarms; if it’s too large, real dragging might go unnoticed. The allowance should be increased if the GPS signal is inaccurate.

 

[Irek]

I used Anchor Pro on iOS for a while, but it was just ok. Lately I’ve switched to AquaMaps built in anchor alarm. I subscribe to AquaMaps anyway and it seems like a full featured alarm that works just the way I want.



Interesting idea. You could put an arduino or Pi Pico on the boat as a LoRa receiver, with a buzzer as an alarm and a couple buttons to set and cancel the alarm. That part would probably be pretty simple and cheap. The harder part might be keeping the anchor end powered and waterproof. In crowded anchorages it also would get involved in the borderline religious debates over whether using a tripling is allowable etiquette.

I am retired MarEng and electronics is not my strong part. I have been looking for some time for an electronics designer who could put together stuff available on the market to get workable system. I know what is needed but LoRa, WiFi transmissions and receiving brings blank in my memory. Never worked with it. Anyone knows how to find a specialist like this? /ik

 

[NatalieG]

We've tried a few over the years. The thing that surprised me is how often the

phone is the problem, not the app — background GPS getting throttled, volume

not loud enough with hatches closed, or DND still on from earlier in the day.



What worked for us was running the alarm app on an iPad and pointing a Blink

camera at the screen. Go ashore for dinner, check the camera — you can see if

the alarm's gone off. Not exactly elegant but it works.



On board, we run one on the MFD as the primary and the iPad app as backup.

Whatever app you go with, worth testing it properly — set the hook, set the

alarm, motor out of the radius and see if you actually hear it from below.

 

[Captain Larry-DH]

We've tried a few over the years. The thing that surprised me is how often the

phone is the problem, not the app — background GPS getting throttled, volume

not loud enough with hatches closed, or DND still on from earlier in the day.



What worked for us was running the alarm app on an iPad and pointing a Blink

camera at the screen. Go ashore for dinner, check the camera — you can see if

the alarm's gone off. Not exactly elegant but it works.



On board, we run one on the MFD as the primary and the iPad app as backup.

Whatever app you go with, worth testing it properly — set the hook, set the

alarm, motor out of the radius and see if you actually hear it from below.

Try Aqua Map to do this much more reliably and full function - see my prior post https://forums.sailboatowners.com/t...rite-anchor-alarm-app.1249942187/post-1846724

 

[NatalieG]

Great thread. @Foswick's point about apps silently going to sleep is spot on — I've had it happen and didn't even realise until I woke up and checked my phone. The alarm icon was still there but the GPS hadn't updated in hours.

We ended up keeping a phone app as a backup but not relying on it as the primary. The failure modes are more varied than most people think — it's not just "will the app wake me up." GPS drift in a calm anchorage can trigger false alarms all night, and then you start ignoring them, which defeats the purpose entirely.

That comparison spreadsheet from trimaran-san is really useful — worth bookmarking if you haven't already.

 

[JamesG161]

On our boat we use our Raymarine MFD to alarm us.

However Admiral Sue likes her fully charged iPad [with GPS] Anchor Alarm as her restful sleeping device.

But Captain Jim get big chuckle, when we are weighing anchor [ Sue is at the Bow] and Admiral Sue's Alarm goes off in the Cabin below. [ is is very loud one too ]




Jim and Sue ...

PS: She does forgive me !

 

[SV Temenos]

I appreciate all the responses. Based on the thread feedback I gave up on the phone app idea. I hadn't realized the issue with it so thank you for pointing it out. I'm now working on getting signal K to run on my Victron Cerbo GX. I have all that working and am now looking for an anchor alarm to run on / with signal K. I can get notifications from that anywhere and is already running 24/7 so I won't need to add another battery load. Has anyone done this?

 

[Rival41Sailor]

After 8+ years of full-time cruising, we’ve been using Hold Fast Anchor Alarm (anchoralarm.app) recently and it’s been the most reliable we’ve come across so far. The GPS tracking has been very solid (no random drift or dropouts), and it also has a GPS loss alarm, which is surprisingly useful overnight if the signal gets interrupted.

It’s also very simple to use compared to some of the more feature-heavy apps, and the interface is clean enough that you’re not messing around with settings when you’re tired after a long day.

One feature we’ve found genuinely handy is the share option, which lets you check the boat remotely from a browser when you’re ashore.

No app is perfect, but this one has been the most “set it and actually sleep” experience we’ve had so far

 

[marcham]

I use the anchor alarm app that comes packaged with SignalK. SignalK runs on the Victron Cerbo, which has a USB GPS puck.... so a super low power method of feeding position and being alerted in case of drift. (I haven't dragged in 20 years ! )

 

[marcham]

Here's an example of the signal-k add-in:

I usually set it from the helm, as Signalk web ui is accessible directly from the Chartplotter(B&G), but you can also reposition the anchor location after the fact.

 

[capta]

Having never used one, I don't know if I should stick my nose in this thread, but here it is.
I consider my anchor and tackle to be the most important safety equipment on any boat I'm on. If I can't sleep well without an app on my phone, then my anchor and tackle aren't doing their job. I don't think I could sleep well knowing that I had left my safety, and that of any others aboard, to a bunch of circuits and a tiny battery.

 

[dLj]

Having never used one, I don't know if I should stick my nose in this thread, but here it is.
I consider my anchor and tackle to be the most important safety equipment on any boat I'm on. If I can't sleep well without an app on my phone, then my anchor and tackle aren't doing their job. I don't think I could sleep well knowing that I had left my safety, and that of any others aboard, to a bunch of circuits and a tiny battery.

+1

dj

 

[Cap'n Deke]

I don't use one but only because I usually have enough crew aboard that I don't worry about it. Someone is usually on watch and if weather is angry, someone definitely is. But I have learned not to be so arrogant as to believe that my equipment or anchoring technique are infallible. Nothing wrong with a second opinion from a piece of technology. I trust my ability to do math in my head, but I still pull out a calculator when it matters.

If there is something that increases your safety margin without being a burden on the crew, that seems like a no-brainer. If a person cruises solo and doesn't use an anchor app solely because they think their equipment and technique are bulletproof, that person must have had led a charmed existence. My experience is that both are found inadequate, if you sail long enough.

 

[Captain Larry-DH]

If there is something that increases your safety margin without being a burden on the crew, that seems like a no-brainer.

This is the perfect response to @capta You’re not relying on the app for safety, just as you don’t rely on radar without using your abilities in other ways to keep watch. It’s just an extra enhancement to your vigilance.

 

[shemandr]

On my H356, which sailed around on its anchor, I never needed an alarm. If the boat didn't snap up regularly I knew we were dragging. With the aft port open I would get regular periods of breeze alternating with no breeze. My sub brain (There is no Uber Brain available) acclimated to that rhythm. Was I sound asleep? Probably not. There is a sub conscience awareness while aboard that I believe is different than on land but still powerful.
One time when I set an alarm, it woke me up many times with its shrill alarm over nothing. Granted I didn't have it tweaked correctly but it was one of a few worst nights I've had on board. And there's been a few to compete with.

 

[Cap'n Deke]

One time when I set an alarm, it woke me up many times with its shrill alarm over nothing.

I have that too. On my boat, his name is Carlos.