Industry NB:- We want a better anchor alarm not a better anchor!

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With all the talk about better anchors and the pressure from the industry for us to buy their latest anchors, I would like to make a plea that they should invent an anchor alarm that really works, and put new anchor developments on the back burner. Thanks.
 
Many thanks for that. I've had a good look at them and as you say, the Marine Direct system is terribly expensive. I'm not quite sure how it works. It talks about being an accelerometer but describes a system that seems to be a load cell with telemetry. The Anchorwatch is simply a load cell but it is on deck so doesn't need telemetry - hence is 1/10 the price. I don't see how a load cell is going to give a reliable anchor alarm. It could be that I am missing the point - what do you think of these systems?
 
Surely the GPS is good enough for most situeations

My GPS allows for an alarm at 0.01 miles. I usually use it at 0.02 which is about 40 yards. It seems to work reliably.
If you are in a crowded anchorage or a situation when the GPS accuracy is poor then you may still have a problem.
In practice its rare to use less than 10 metres of chain sou you will get a 20 metre shift at the turn of the tide anyway.
 
Surely if you had the ideal anchor, you wouldn't need an alram?

Also, if you ashore, how do you firstly get the alram and secondly react to it?
 
Most of the anchorages here in the western Med are quite small and very busy. This year I have witnessed 4 incidents that resulted in serious damage due to dragging and all were due to the dragging craft colliding with another craft, not going aground. All of those cases but one occurred when the owners were on board. There was one other case in which a motor yacht dragged and drifted out to sea, while the owners were ashore but they chased it in their tender (at gone midnight!) and recovered their boat.

Most of us use GPS anchor alarms but either they wake us up several times a night or they fail to go off before you have the risk of a collision. I don't regard it as an acceptable anchor alarm.

Edit:- Edited the thread title back to the original - it had been changed by the poster.
 
Yes, obviously that is true but we aren't anywhere near an idea anchor. Anchors are dreadful. If the reliability of any other piece of yachting kit was half as bad as the best anchor it would be thrown out as useless. Despite thousands of years of evolution, an acceptable anchor seems impossible, let alone a perfect one!

I have an alarm that works via a GSM mobile. I get intruder, bilge and any other alarm I want, SMS texted to my mobile. Cost around £100 so not a big ticket item. I can't speak for others but when conditions look challenging we don't leave the boat unattended. Sometimes we stay on board for a couple of days - and watch several boats in the anchorage drag past us - while we watch, fenders in hand, quite often.
 
Have just read more of the last anchor thread - didn't realise it was still going!

According to certain others there current anchors are fine (so long as the whole system is considered).

I agree with you, however, particularly over the CQR. I think there is much improvement to be had, and should welcome the work put into it.

Presume then there is some way in which a GPS alarm can be sent as a text? That would be useful. Perhaps garmin should build it in (plus maybe new lat / long plus course and speed.

I do think more focus should be on digging in rather than peak load - biggest risk is when the tide changes and/or the wind changes direction.
 
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According to certain others there current anchors are fine (so long as the whole system is considered).

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No, the tests they are talking about were all in sand!! Nobody can be sure what they are actually anchored in unless the bottom is visible.

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Presume then there is some way in which a GPS alarm can be sent as a text? That would be useful. Perhaps garmin should build it in (plus maybe new lat / long plus course and speed.

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I can wire my GPS anchor alarm into my GSM alarm system that sends me a SMS text. I don't think you need to know anything other than 'get back to your boat' - what would you do with lat/long? /forums/images/graemlins/smile.gif But none of the present anchor alarms are really satisfactory. I am hoping that Alain will come back to me regarding my comments on the ones he posted. There is a simple product that West Marine used to make and the design is now in the public domain as a DIY project. I am wondering whether to try it.
 
I know you're looking for a reply from Hylas (but)

The "AnchorWatch" seems useless, because all it tells you is the tension in the rode.

The "Marine Direct" system seems to use accelerometers to determine that the anchor itself is moving. This would be a pretty good way of detecting the anchor dragging, just a shame it's so expensive (exchange rate approx 4$au = 1 GBP??). Neat approach to the telemetry, though.

Makes you wonder if there's a "middle way" whereby something "listens" to the rode and picks up vibrations as the anchor drags, much in the same way as you listen out for vibrations through the hull? Wouldn't be as discriminating as the "Marine Direct" alarm, but maybe more use than the "Anchor Watch".

Andy
 
You are into artifical intelligence, and how to teach a computer to pick up the 'vibes' that something is wrong. Humans are hard wired to pick up things that might not make sense to a computer, so a very hard problem for some computer wizz kid?
 
High misterg just to make sure you have got it right and I think you are referring to Australian Dollar then one $A cost 40 UK pence so divide the oz cost by 2.5. The way you wrote it you multiply by 4 (I wish)
What you need for an anchor watch is seperately anchored ultrusonic trnasponder which can be dropped near the anchor. Using time for sound transmission it could constantly monitor the distance your boat is away from the transponder which would not move if the anchor was dragging.
An even better arrangement would be to have an interegator attached to the anchor which monitored distance to the separately anchored transponder ie within a few metres such that even 1 metre of anchor drag would easily be identified. It would have to be relayed back to the vessel.
Obviously the first arrangement needs no electronics on the anchor so would be more robust and probably adequate for the purpose of monitoring the vessels distance from a specific spot as marked by your transponder sitting on the bottom (on the end of a light line and buoy) (brainstorms...we got em) olewill
 
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Anchors are dreadful. If the reliability of any other piece of yachting kit was half as bad as the best anchor it would be thrown out as useless. Despite thousands of years of evolution, an acceptable anchor seems impossible, let alone a perfect one!


[/ QUOTE ]

Half the trouble is that anchors are underspecified even y the companies selling these products. If people used a bigger anchor, and heavier chain, they could sleep peacefully - ask 90% of cruising yachties.
 
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With all the talk about better anchors and the pressure from the industry for us to buy their latest anchors, I would like to make a plea that they should invent an anchor alarm that really works, and put new anchor developments on the back burner. Thanks.

[/ QUOTE ]
Solution: wait for the new European satellite positioning system to come online, which will be more accurate than the American one... and not reliant on the whim of the US military.
 
Pleased to hear from you - the beauty of an open forum is that you get a diverse range of opinion and experience.

Is rode tension "absolutely useless"? You go on to talk about "listening" for sounds of dragging. A load cell in the rode is an excellent "microphone" but, as Brendan says, the problem is how to teach it what to listen for. I imagine that some failure modes result in a characteristic load pattern (the Sail report suggests that).

The big problem that we all had in the western Med this year (I don't know whether that is always the case or whether this year was abnormal) was heavy weed. The weed forms a ball around the anchor making it impossible for it to get a hold. Even if you dig it in and it seems OK it seems to get weed trapped around it and ends up skating over the bottom like a clump of tumbleweed. Most types of anchor were affected except the Danforth and local favourite, the Brittany. I doubt whether any characteristic sound would be heard in this process.

The Marine Direct product says that it works with an accelerometer but when you look at the product photos and read and watch the video, it looks to me as though it is a load cell. Do you think that they might be deriving acceleration from load?

I thought that the AchorWatch price seemed quite reasonable. It wouldn't be worth fiddling about with load cells and instrumentation amps if you can buy a product like that off the shelf. Furthermore, Hylas told me that he respects the man behind this product, which is a good recommendation. However, from the product description, the principle of operation is that one digs the anchor in, recording maximum load and this is deemed to be a safe load by the system. Provided the load does not exceed this value the system does not alarm. That might be fine on a sand, mud or clay bottom but is useless on weed where the anchor becomes progressively fouled over time, losing a little more of its ultimate holding force as time goes by, until the anchor is in the middle of the clump of 'tumbleweed'.

Maybe we could be a bit more cunning. Suppose we take an (approximate) wind strength derived from a simple instrument such as a thermistor velocity meter and derive (or look up) an expected range of maximum rode forces due to that wind. Now, if the load signature on the rode is far from the signature we would expect from the wind, we could generate an alarm.

One problem is that dragging usually happens suddenly. One minute you are perfectly well anchored and the next, you are making way down the anchorage at up to a knot or two. Very quick, very unexpected and very disconcerting.
 
Sell the boat and live ashore until that becomes available, eh? /forums/images/graemlins/smile.gif

No, accuracy is not the problem with a GPS anchorwatch. Boats move due to wind and current and in an anchorage all boats move together. You might have a long scope - if you are anchored in 10m you might have 60m out which, roughly, gives a circle of radius 50m in which you might be at any time. i.e. 100m movement is perfectly normal. As soon as you set GPS alarms in a crowded anchorage they go off too often. What you want is a GPS on your anchor, not a GPS on the boat! I don't think it's possible, tho'
 
Hold on.

If you anchor and you have that 50m circle as you describe, then you just set the anchor alarm in the middle of the circle, yes? Where the anchor is? And give it a 50m allowance. I guess the problem here is you have to know exactly how much rode you pay out, but that is solvable. From the depth you could work out the actual over-ground radius that any given amount of rode provides (from the trigonometry). If this is all computer driven then it could even be smart enough to know the tides, and dynamically adjust itself over time, so low tide doesn't mean you go over the limit. And it could compensate for the maximum amount of stretch in the rope, and so on.

So in strong winds you will be right up against that radius of 50m, however it's calculated, correct? Because the chain and or rope will be pulled straight. You can't go over it. So if you go over it by even 1m, it must mean the anchor has moved.

Wind changes direction, you just move to a different point on the circle's perimeter.

Am I missing something?
 
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Half the trouble is that anchors are underspecified even y the companies selling these products. If people used a bigger anchor, and heavier chain, they could sleep peacefully - ask 90% of cruising yachties.

[/ QUOTE ]

None of the dragging incidents that I witnessed this year were in conditions where the anchoring system was anywhere near its rated limit. People were dragging in as little as F4 but typically 5/6. I have discussed anchors and anchoring with dozens of yachtsmen this year and I don't remember a single one saying that they felt a bigger anchor or chain would help. Most people think that the key factor is the bottom - some bottoms are good holding, some are patchy, some are dodgy and some are downright dangerous. After that, the choice of anchor is seen to be a matter of personal preference, like one's choice of aftershave.
 
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Hold on.......Am I missing something?

[/ QUOTE ] Yes, it's not easy to set the anchor watch at exactly the right point when you are short-handed and in any case you can drag quite a way before you finally set. Like most people, I use the GPS anchor watch but it isn't very good which is why I started this thread. It's also why people are trying to invent anchor alarms!
 
Has anyone yet remembered to set their anchor alarm as they actually drop their anchor?

The alarm setting options on all 3 of my GPS's don't allow a retrospective alarm set: they all action from the position you are at when you "set" the alarm to "on", which often means you need to allow for the complete swing diameter rather than just the radius.

Anyone know any better way of doing it?

Pops
 
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