Portable Anchor Alarms

sailcruiser · Jan 5, 2012

I use a Bluetooth gps that sits above on deck. I don't know if it works with android for certain but may be worth a peek. It's a Dual xgps150. Amazon had them not long ago for about $80. I know ActiceCaptain just released the free DragQueen but I haven't tried it out yet. SC

Bill Roosa · Jan 5, 2012

tie a string across the companionway. Attach a long line to a dinghy anchor and to a frying pan. Once anchored lower the anchor to the bottom and run the line over the string so the frying pan is lying on the floor in view of the birth. If the boat drags anchor or shifts due to a wind change (and potential drag) the line will pull the frying pan toward the companionway then up and start makin a racket as it bangs on stuff.
You can put slack in the line to account for sailing on your anchor also.

seadaddler · Jan 5, 2012

76CX

I use a 76cx anchor alarm and the batteries last a long time and my wifes Dri=oid is such a power such would not even think of that and my Ray C-80 must use some power but the 76cx which WM had a super deal for it and the g2 chip,I use it for my backup on my boat and also very handy Kayaking here in Florida.
Nick

Stu Jackson · Jan 5, 2012

If you go the Garmin route, you do not need the CSx, which has an altimeter and compass, just the 76Cx.

I have never used an anchor alarm in 30 years. I prefer to anchor securely, using Maine Sail's method. I must admit I do anchor here in Northern California in protected waters. I also admit I have dragged an anchor, but never went to sleep until I knew it was set. I'm still here, but I'm sure many of you others anchor in less protected spots than I have available to me and in varying wind conditions.

That said, if your anchor was subject to drag, then unless the weather changed drastically (for a recreational boater there's always a change in the weather report), then anchor system sizing and technique ought to take a lot of the guesswork out of it.

Ed H · Jan 5, 2012

sailcruiser said:
I know ActiceCaptain just released the free DragQueen but I haven't tried it out yet. SC

I saw that too...Anyone use it yet?

gpdno · Jan 5, 2012

Ed H said:
I saw that too...Anyone use it yet?

Yes, I have used ActiveCaptains anchor alarm. Works well on my iPhone. Just need to keep the phone plugged into the charger otherwise the phone battery will die, then no alarm.

Ed H · Jan 6, 2012

Thanks...I will give it a try... you can't beat the price.

Ed H · Jan 8, 2012

Nodak7 said:
Ed, I looked at it and you have to be careful with the accuracy of the GPS on the cell phone. I found mine was pretty far off and not even close to where I would trust it while I was sleeping.

I understand that.... It would be better than what I have now (nothing)... But what about this- I don't really care about where "x" is, I just want to know when I am 100 feet away from "x".

MLampner · Jan 9, 2012

Nodak7 said:
Ed, if "x" moves, because the GPS is not accurate, then how do you know when you are 100' away because you are are 100' away from "x(2)" not "x".

I actually have found the iphone's GPS to be quite accurate, but that is true above deck. Have had some trouble holding lock below.

Jackdaw · Jan 9, 2012

Nodak7 said:
Ed, if "x" moves, because the GPS is not accurate, then how do you know when you are 100' away because you are are 100' away from "x(2)" not "x".

There is a difference between absolute and relative accuracy in GPS technology. Absolute accuracy is how far the device thinks you are from where you actually are. This is the typical GPS error people think of and is important for map overlay of but matters less for anchor alarms. Relative accuracy means repeatable reads of a fixed position over time. This is more what is needed in anchor alarms, and the good news is that lower cost GPS chips that might suffer with TTFF and/or absolute accuracy do better here. And there is things SW developers can do in software (like dwell) that help things.

All that might make you sleep better. But if you did not I'd understand! ;^)

Bob 04 H260 · Jan 9, 2012

I use my handheld GPS over night when I have concerns with the anchor. Usually just let it run as I come into the anchorage then let it run for a couple of hours to see how the boat swings and if it holding well. If we are having a "bad night" I turn it back on and check it if I have any concerns without even lifting my head off the pillow. The picture below was a night on the north end of Lake Worth with unexpected 40kt south wind. We had a bimini and boom tent so a lot of windage on a small boat. As you can see anchor held, 12 ft of water, 50 ft chain and a 22 lb Delta anchor. It was our 2nd day there so anchor was well set. We were in a slip the next night

. This GPS model has an anchor alarm but I prefer to just look at the screen to see what is going on, our boat does a lot of sailing on the hook and will set off any anchor alarm.
Bob

Jackdaw · Jan 9, 2012

Nodak7 said:
Jackdaw, thanks for the information! I think what you are saying is the cheaper GPS's are sufficient for anchor drag alarms. Correct?

Is there any way to tell from looking at them? Is this data mentioned in the specifications for the GPS?

I'm saying that even if your phone's GPS is very slow to get a fix, or seems erratic when running a car nav program, the relative accuracy of its GPS might be just fine for use with an anchor alarm.

I'd suggest experimentation and good prudent seamanship. Try an app that records tracks and place you phone in a secure place in your boat, connected to power. Ideally no one will be able to pass over it, either below or on the deck, blocking or changing GPS reception. Look at the track to see if it looks 'OK.

I talked to Jeff before he released Dragqueen and he has done some smart things in the app. The app reports accuracy (really EPE, or estimated positional error), and includes delay before an alarm sounds. This is a good idea because it prevents the app from tripping off of one or two 'outlyers', or bad reads. He's done a good job.

Dan Hill · Jan 9, 2012

I like the frying pan app

. Uses less AA batteries

David in Sandusky · Jan 9, 2012

Garmin 76cx

Our handheld gps works fine when we need it, even inside the cabin.

But most of the time, with an anchor matched to the bottom and well set with a scope of 7, we don't bother with an alarm, and sleep just fine.

Portable Anchor Alarms

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