Anchor watch

[gimmick]

Does anyone know of a GPS (preferably hand held) with an anchor watch function, and an alarm which is reasonably loud. The alarm on my present GPS is difficult to hear even if I am listening for it.

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[johmal]

My Garmin GPS 76 has an anchor watch feature - but I have never tried it. Have a look at their web site for more info.

John M

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[wooslehunter]

Garmin GPS72 has the same function. It's not very loud but it woke me up a while ago. The anchor wasn't dragging but I set the alarm too fine - you set a limit of movement. Bear in mind that GPS position will easily wander 10m.

On my boat, the unit is mounted about 3 feet from my head though. Much further and it wouldn't have been loud enough and I'm a shallow sleeper.

I posted some time ago about this, thinking of a gizmo that would listen to the NMEA output and wail loudly in the event of a drag.

There doesn't seem to be one but there are lots of people around who are willing to offer advise on the correct way to anchor. Clearly they are so good that they don't see the need for any precautions.

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[Miker]

Pity. A cheap gizmo for an anchor watch would be handy. I already have a fixed and handheld GPS, and don't particularly want to fork out for another. I'll just have to pluck up enough courage to anchor without one.

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[pvb]

Here\'s one...

To get a really loud alarm, you need a dedicated external sounder. I don't know of handhelds which will drive an external alarm, but the excellent Garmin 152 fixed GPS has an anchor watch function plus the capability to drive an external alarm. The yellow wire on the power/data cable goes negative on alarm and will drive a 100mA load (put a relay in if the sounder needs more than that).

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[andy_wilson]

What about the deep/shallow alarm on your depth sounder?

My ancient Garmin 65 has an alarm plenty loud enough to wake someone sleeping in the main cabin or quarter berth, or in the cockpit if sailing and a waypoint alarm is reached.

No good under engine though.

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[snowleopard]

all those beeps

my garmin 128 wakes me even though not in the same cabin.

trouble is, we have so many alarms on board (gps, depth, dsc, smoke, gas, CO, mobile phone etc) that you wake from a bleary state trying to work out what the emergency is. the worst was when i accidentally set a countdown alarm on the ship's clock. it took me ages to find that. for some reason these electronic sounds beat the ear's direction finding ability.

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[mikesharp]

We use a garmin 128 on our 60 footer but the anchor alarm has an accuracy problem ie too accurate. With a long keel and 25 tonne of boat the swing we can get with a 6 times scope on the chain when the tide changes can be quite some distance and produce a number of false alarms during the hight. It is still worthwhile using one though.

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[webcraft]

Why is it worth using something that disturbs your sleep and puts you into a state of alarm for no good reason?

I sometimes set the deep/shallow alarms on the echo sounder but this has woken me up when we haven't dragged - presumably false echoes.

I don't think GPS or your estimate of your swinging circle is accurate enough if you are in a tight anchorage . . . but if you are going to use it then set it for a 50yd drag - that's usually calculable and worth waking up for.

If we need anchor alarms better get one that phones you in the pub to let you know when it's time to get back . . . these events are harder to spot than the ones that happen when you're actually on board.

- Nick





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[MainlySteam]

We always set the GPS anchor alarm unless stopped for only a few hours and find it satisfactory to the extent that apart from very heavy weather it lets us sleep confidently. We set it for the approximate swing radius, though usually just use the measured chain let out though, plus a bit more than the GPS system error (say 20m) and only have the very occasional false alarm - we try, without making a mission of it, to centre it close where we dropped the anchor, and if we have missed that is the cause of the false alarms we have had. We set it very tight if swinging takes us close to shore should the wind be/go onshore.

We never use the sounder as an anchor alarm - many places we anchor are the same depth right up to the rocks and right across the anchorage (right across the anchorage is a common occurance, and a sounder will not then provide an anchor watch).

It works because we have never dragged.

John

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by MainlySteam on 19/10/2003 06:48 (server time).</FONT></P>

 

[wishbone]

To save spending on expesive kit why dont you buy or make a small battery powered amp with built in mic. I should have a circuit diagram somwhere or you could try Maplins. I seem to remember that you could buy a telephone ring amp that picked up the sound and amplified it.
if you don't have any luck pm me.

Come to think of it, there is a electronic kit shop in Liverpool on Dale street it's still there I used to shop there over 25 years ago when I had my electronic boffin hat on! cant think of the name try yell.com......

Wishbone
Rolling, rolling, rolling keep them doggies moving!
Where’s me chuck wagon gone?






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[trevor_loveday]

The yellow wire from a Garmin 128 (quite a popular GPS) can drive an external buzzer. I bought a small one from Maplins for a couple of pounds that is quite loud enough to wake me.

I guess other GPS's have a similar interface (although why anyone would want to buy anything other than a Garmin is quite beyone me...! /forums/images/icons/wink.gif).

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[bob_tyler]

You stated: "It works because we have never dragged"

If you've never dragged, how do you know it works????!!!!

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[MainlySteam]

Just being perverse, of course. However, we do frequently find it does work when we merrily raise the anchor, start off and - you guessed it - the alarm goes as we yet again forgot to unset the anchor watch before departing!

In any event, while it has never been needed in anger we always set it without fail.

Regards
John

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[duckmanton]

I have read of varies cheap methods of alarming oneself if you are draging.
One in PBO using a personal alarm set up, as its cheaper version which is a weight dropped over by the anchor with a small dia rope coming back onboard tied to the hatch, holder upper. Boat moves weight stays in same spot, holder upper pulls out, hatch comes down. Wake you up. Why use a GPS, with all its false alarms.

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[dulcibella]

These are all helpful ideas, but if there arere any real doubts about ability to hold, there is no substitute for a human anchor watch rota or, if short-handed, getting up every couple of hours to check. I don't think many experienced yachtsmen sleep through the sound of rumbling chain or a significant increase in wind strength.

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