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Phone anchor alarms

Neeves

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20 Nov 2011
Messages
6,306
Location
Sydney, Australia.
For those of you who rely on anchor alarms, specifically phone anchor alarms, there might be an interesting thread on Cruisers Forum that you might want to follow

Anchor alarm app stopped working on iPhone - Cruisers & Sailing Forums

It may turn out to be 'operator' error, an error in the App or something specific to iPhone It may also be something to check anyway.

Jonathan

Alarms and complacency

A few years ago I solicited comments on the frequency with which modern anchor dragged and apart from catching supermarket trolleys and the like no-one admitted that their modern anchor had dragged. I treat the comments with some caution as their does appear to reluctance to admit that ones spanking new (and expensive) modern anchor is not all it is cracked up to be. However we have not dragged either - so maybe my caution is misplaced.

It might be complacency but we are sufficiently confident with out anchors and use of same that we only set an alarm, with the chart plotter whose aerial is 'outside', in exceptional circumstances (and it has a piezo electric alarm added), when we expect the arrival of a major front or we are anchored somewhere with strong tide reversals (not common where we cruise).

We also have a berth mounted compass and when a front is expected we can see the orientation of the yacht, has or has not, changed, is changing, and that the front is arriving.

We thus have virtually no experience of phone based anchor alarms.
 
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ctva

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8 Apr 2007
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2,838
I have never relied on an anchor alarm.

A good anchor, chain and setting should be enough. If it is that bad or iffy to need an anchor app, stay up or move.
 

RupertW

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Greenwich
I have never relied on an anchor alarm.

A good anchor, chain and setting should be enough. If it is that bad or iffy to need an anchor app, stay up or move.
I spent years anchoring without an alarm but they are so simple to set that I’ve used one or two for the last few years. Basically I wouldn‘t go to bed unless I was pretty sure it was safe anyway but it’s nice to have, although the odd false alarm has gone off when the GPS position appears to briefly move a few tens of metres very occasionally.
 

Stemar

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12 Sep 2001
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Home - Southampton, Boat - Gosport
A good anchor, chain and setting should be enough. If it is that bad or iffy to need an anchor app, stay up or move.
That sounds great in theory. If only life were so simple!

I have an oversized Delta and it's never let me down once it's dug in, but I wouldn't hesitate to set an alarm if the weather was looking iffy, though I doubt very much that I'd sleep through the kind of wind that would set the anchor off wandering. A failure of chain/rope/splice/shackle is far more likely. In any case, if it's that bad in and around the Solent, there's no need to sit it out in an exposed anchorage.
 

duncan99210

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Winter in Falmouth, summer on board Rampage.
On anchor alarms generally, I’ve been using the, for peace of mind for some years now. The first ones I used were very buggy and prone to false alarms, as they didn’t average over a number of fixes, so one spurious fix would cause the alarm to go. The one I now use is not prone to false alarms and has been an aid to decent sleep for about 4 years.
I being idle this morning but once I’ve had breakfast I’ll try the app out in the garden and see if it works or if it fails as per the link. I know that there have been a couple of updates to iOS recently and iOS 14 is due out later this week, so it may all be related. I’ll post again later after breakfast: lazy day today as it’s too windy to take a novice crew out in a gig!
 

scruff

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2 Mar 2007
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Over here
We've started using OpenCPN this season on a w10 tablet device mounted in the nav area. On it, it is so easy to see your snail trail indicates where you dropped the hook and to drop a mark on it with anchor alarm set at the requisite radius.

This is the first year of having an anchor alarm and I must say when it's pretty unpleasant outside, it's nice to be able to check on your situation without getting wet checking your transits in the cockpit. I was a lot more relaxed this year riding out a 40kt summer gale at anchor.
 

FlyingGoose

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12 Feb 2019
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The Known Universe
Have used the alarm twice this year , in my phone and wife had a different one on her phone,
I can handle pretty much anything at anchor , in the sense of I can sleep and do whithout
Been bothered .
So we have dropped the hook in places that might not be suitable for others .
The alarm was used on 2 blows 40 knots plus I never felt my anchor or chain would fail I was more worried about wind shift and the anochor moving
Anyways it was interesting to see the pretty patterns the track of the boat made on the app and how the boat moves .
That's was a 5 week trip so used twice. No anchor moved 25kg Rocna (other anchors are available)
 

RJJ

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14 Aug 2009
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....does the panel drop the "pin" at the anchor (with radius set to the same as the scope) or at the initial resting point?
 

scruff

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Over here
....does the panel drop the "pin" at the anchor (with radius set to the same as the scope) or at the initial resting point?
I tend to approach anchoring spot upwind, drop hook and fall back. This leaves a sharp ^ angle showing on the snail trail. I drop the marker approximately on the apex of the snail trail. The radius set to be length of rode out + an arbitrary bit (I use 15m). This obviously ignores the effect the depth of water has on the hypotenuse of the rode, but accounts for the nav area being several meters away from the bow.

it's not an exact science and I'd suggest you only want to know once you've dragged more than a boat length to avoid erroneous alarms going off.
 

Baggywrinkle

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Ammersee, Bavaria
I go to bed with navionics recording my track - I'm a very light sleeper and wake up if the wind, waves or anything else changes significantly .... first I check the track to see where I've been swinging and if I've moved significantly - then I listen for any signs of shouting, engines or watch to see if there are any powerful searchlights being used. If I'm suitably concerned I'll pop my head out of the companionway hatch to assess the situation.

I'm fairly confident my boat wont move but you can never be sure ... when it gets really bad I sit in the cockpit with a bug-out plan ready.

I've watched some utter chaos in anchorages - including a couple in a large Mobo fast asleep with their genset and aircon running, merrily drifting through the anchorage - it got to the point where a smaller Mobo was throwing stuff at their patio doors to try and wake them after everything else had failed.

I've not had much success with anchor alarms ... but have been meaning to have another look.
 

RupertW

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Greenwich
....does the panel drop the "pin" at the anchor (with radius set to the same as the scope) or at the initial resting point?
We spend most nights at anchor where possible. I tend to sort the anchor out, snorkel over it to check, sort out the bridle and let a bit more out and then finally get round to doing the anchor alarm. I simply go for 80% of the known chain length out in the direction that it is pointing. Then adjust range and/or position if really needed over the next couple of hours. It’s only job is to tell me if we are dragging dangerously so I don’t mind a little inaccuracy by extending the range.
 

MM5AHO

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1 Oct 2007
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Central Scotland
I've tried various anchor apps for phones, just to see how they work more than to rely on them.
The problem as I see it is that they tell you after the event. They Say "Wake up, you HAVE already dragged anchor". They alarm when you pass a set threshold of distance according to gps.
I'nm working on a revamp of a system marketed some years back called AnchorWatch. Fitted into the rode, it monitors anchor loading and can predict an anchor dragging before the event. Not sure how that will go, but its an interesting challenge to convert a somewhat expensive 1980s technology device to modern electronics and physics.
 

duncan99210

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Winter in Falmouth, summer on board Rampage.
Back to Neeves original point of iOS based alarms not working after a report via cruiser net. Having now motivated myself out of bed, I’ve checked my app (Anchor!) which is working fine.
As to using an app or not, that’s down to personal choice, no compulsion going on here.... I work the same way the RupertW does: get the anchor settled, set anchor position by pointing the phone at the anchor and adding the rode minus a bit then set up the alarm zone depending on the anchorage. If the shore is close or it’s crowded then the alarm zone is set tight to the rode length, if there’s more room, then the zone is set further out. No point at all in trying to set the app whilst anchoring as everyone is already too busy to start fiddling with the phone or plotter.
 

Rocksteadee

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25 Jul 2011
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Top of the Hamble
Drop anchor and simultaneously drop the pin on the chart plotter, Navionics on iPad, ‘Anchor-watch’ app on iPad and phone.
and because I am concentrating on the position i want to fall back to, I never remember.
So having previously set track on plotter and Navionics I drop the pin at the apex of the V.
If there is an apex after driving round a couple of circles to check depth and sort out where I would have to drop to fall back in the correct place.

Now having got that sorted.
I set anchor watch app on phone and iPad.
check I have internet connection on iPad (carry a internet dongle)
the app I use has a nifty feature where the iPad on the boat can text the phone and send an email to me whilst ashore.
Bear in mind that the GPS signal can wander by as much as the length of Rode I have down
 

sailaboutvic

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26 Jan 2004
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Med
Which ever way you set the alarm it all works as long as it set right and you have a good GPS signal .
I use a anchor alarm every time we anchor the reason for this is once it's set we can turn it off and then turn it back on if the time comes we need it , it remember where it was last set .
There where time when we didnt set in this way in the pass thinking all good then a thunderstorm and roaring wind and rain turn up half was through the night you wish you set it .

I agree at times there are lot to be done while anchoring , chooses a spot, working out where you going to end up, other boats and what their doing, depth so on and so on but I still drop my pin about 30 second once we start to drop then once set and while the chain is stretching out I set the destination I need , this works for me .
 

noelex

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2 Jul 2005
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3,593
So having previously set track on plotter and Navionics I drop the pin at the apex of the V.
If there is an apex after driving round a couple of circles to check depth and sort out where I would have to drop to fall back in the correct place.
This is a good technique. One tip, rather than setting at the apex of the “V” is to displace the centre point forward by the distance between the bow roller and the position of the tablet/phone. So if your phone/tablet is 10m back from the bow roller the correct point for the centre of the alarm is 10m in front of the “V”.

The apex of the “V” is only the correct point if the phone/tablet was held over the bow.

If the wind stays in same direction using the apex of the “V” does not cause any problems, but if the wind shifts and the boat swings the error doubles.

This diagram might help:
 

Attachments

webcraft

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8 Jul 2001
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I have never relied on an anchor alarm.

A good anchor, chain and setting should be enough. If it is that bad or iffy to need an anchor app, stay up or move.
Hope you stay lucky. It is always possible for an anchor - any anchor - to fail to set 'hard' on reversal, especially in a weedy seabed.

Happened to us ten days ago. The anchor alarm allowed us to monitor the (slow) drag and survive until morning without having to take drastic action.

Invaluable IMO.

- W
 

lampshuk

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10 Sep 2013
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Solent
...
the app I use has a nifty feature where the iPad on the boat can text the phone and send an email to me whilst ashore.
...
That does sound nifty, and would alleviate my repeated drag-panic when I'm ashore out of site of my Moody 31 (hopefully inappropriately named) "Drifter".
Even better if it provides the facility for me to query the anchorwatch device (about every 7 minutes) asking "Are you still there???".

Which app are you using, may I ask?
 
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