Reply
 
Thread Tools Search this Thread Display Modes
 
Old 03-18-2019, 06:43 PM   #1
Senior Member
 
JustBob's Avatar
 
City: Bainbridge Island
Country: USA
Vessel Name: Mahalo
Vessel Model: 2018 Hampton Endurance 658
Join Date: Apr 2016
Posts: 433
Garmin Anchor Drag Alarm

Being a lifelong software designer / developer, sometimes I'm amazed at what people create, or fail to create. When we anchor, my wife is at the helm and I'm out at the anchor platform. I have a wireless remote for the windlass. We have headsets so we can communicate easily.

We have decided where we want to drop the anchor.

There's a MARK button on the Garmin MFD. When I determine the anchor has touched bottom I say "MARK" and she replies "MARK." Then we commencing letting out our scope and setting the anchor.

Yesterday for the first time I thought I'd try the Anchor Drag Alarm. After we set the anchor and shut off the engines, I found the screen on the Garmin 8617. You can see in the picture that you can turn the Alarm on, and set the radius. There's an "Edit" button and a "Recenter" button.

Here is the entire documentation on this screen from the manual:

Setting the Anchor Drag Alarm
You can set an alarm to sound if you have moved more than an
allowable distance. This is very useful when anchoring
overnight.
1 Select Settings > Alarms > Navigation > Anchor Drag.
2 Select Alarm to turn on the alarm.
3 Select Set Radius, and select a distance on the chart.
4 Select Back.


They don't even document two of the buttons, nor do they have any advice on how to use this function.

It seems to me, the center of the circle should be where you think the anchor is located. It seems to me I'm showing Mr. Garmin that, with my anchor mark.

Doesn't it seem like that "Recenter" button would center the circle on the mark? It doesn't, it centers it on the screen.

There's no way to move the circle.

Without luckily floating over the anchor, or starting an engine and motoring to it, it seems the only way to use this functionality is to be ready and hit the mark and turn on the alarm.

Thus far, anchoring is a busy time. We are putting the boat where we want it, monitoring our distance to other boats using the radar, figuring out where we'll end up with our scope, you know how it is.

I suppose this is a minor piece of functionality in the grand scheme of things. I know they are doing amazing work like slaying AutoRouting dragons.

But how fricking hard would this be to make much more useful?

I was on the phone with Garmin today (2 hour call back) about another issue and I asked him about this. Was hoping there was some way to move the circle and I hadn't figured it out yet. I emailed him the picture so we could look at the same thing. He didn't seem to understand why I thought it needed to be improved.

In my software company we fixed little things too. If it isn't right, it isn't right. Why punish users that have selected your product and paid good money?
Attached Thumbnails
Click image for larger version

Name:	anchoralarm-130116.jpg
Views:	81
Size:	99.9 KB
ID:	86528  
__________________
Advertisement

__________________
JustBob
www.mvmahalo.com
JustBob is offline   Reply With Quote
Old 03-18-2019, 07:47 PM   #2
Guru
 
OldDan1943's Avatar
 
City: Aventura FL
Country: USA
Vessel Name: Kinja
Vessel Model: American Tug 34 #116
Join Date: Oct 2017
Posts: 2,952
JustBob, I have never figure out how big the circle should be. PLUS, the anchor alarm is of little good if it wont wake you while you are sleeping. I would think there should be a way to extend the anchor alarm to the stateroom or put a bell on the system so you can hear in in the stateroom.
__________________

__________________
If you must love me, don't love me for my beauty. Love me because I know how to cook.
The burial for my intuitive gene was last month.
OldDan1943 is offline   Reply With Quote
Old 03-18-2019, 08:04 PM   #3
Senior Member
 
Join Date: Jan 2008
Posts: 163
Just download the Anchor Alarm app to your cell phone. Works better, place the phone next to your pillow when you sleep so you can hear the alarm. Best part of all, you DONT need a cell signal for it to work, it’s working off of GPS, which works anywhere��
Taras is offline   Reply With Quote
Old 03-18-2019, 08:13 PM   #4
Guru
 
OldDan1943's Avatar
 
City: Aventura FL
Country: USA
Vessel Name: Kinja
Vessel Model: American Tug 34 #116
Join Date: Oct 2017
Posts: 2,952
Quote:
Originally Posted by Taras View Post
Just download the Anchor Alarm app to your cell phone. Works better, place the phone next to your pillow when you sleep so you can hear the alarm. Best part of all, you DONT need a cell signal for it to work, it’s working off of GPS, which works anywhere��
What is the name of the app you use? I see 6 choices
__________________
If you must love me, don't love me for my beauty. Love me because I know how to cook.
The burial for my intuitive gene was last month.
OldDan1943 is offline   Reply With Quote
Old 03-18-2019, 08:19 PM   #5
Veteran Member
 
AdmiralS's Avatar
 
City: Stony Point, NY
Country: USA
Vessel Name: Varka
Vessel Model: Ranger Tugs R-27 & Helmsman 43 PH
Join Date: Aug 2018
Posts: 95
We use Anchor Pro and are very happy. We tested it over several weeks during the day to check its reliability and found it to be very good.

We can sleep soundly at night with it running knowing that if we drag it will wake us up.

https://play.google.com/store/apps/d...orpro&hl=en_US
AdmiralS is offline   Reply With Quote
Old 03-19-2019, 04:40 AM   #6
Veteran Member
 
City: Waitamata
Country: Aotearoa
Vessel Name: Karinya
Vessel Model: Pelin
Join Date: Jun 2017
Posts: 58
My Grandad made an app for an anchor alarm when I was a kid and it worked pretty well. It involved tying a fishing line to a bake bean can filled with concrete that was dropped beside the anchor on setting. The other end was fastened to a saucepan placed on the galley table under a large collection of pots and pans. If we ever dragged Grandma would jump up with such a start and a shot of adrenaline that she would have us re-set in no time. All the while the rest of us, including Grandad, slept like babies. I like JustBob’s idea of being able to recenter the circle, it makes total sense to me. Better even than Grandmas idea of where best to fasten the end of the fishing line to command Grandads full attention.
BeeJay is offline   Reply With Quote
Old 03-19-2019, 05:18 AM   #7
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 7,668
Bob

We too have been frustrated with plotter anchor alarm choices. Here is what we have done for a very long time.

This may be counterintuitive in the era of "electronics can solve everything" - use the right anchor and rode so dragging doesn't occur. Another tool we use is the depth alarm if really concerned, taking into account the specific anchorage and tide range.

Over the years we have found that using the plotter, with track on, to place a box around the well set anchor answers a lot of questions in the morning. The box should be large enough to compensate for wind and current variation during the tidal changes. Some use circles if available. We have dozens of saved boxes spotted around WA, BC and AK and return to them as first choices.
sunchaser is offline   Reply With Quote
Old 03-19-2019, 06:05 AM   #8
Guru
 
Simi 60's Avatar
 
City: Queensland
Country: Australia
Vessel Model: Milkraft 60 converted timber trawler
Join Date: Jul 2016
Posts: 1,783
Opencpn.

Using mouse, right click > drop mark > set anchor alarm
Grab and drag into better spot if required

https://opencpn.org/wiki/dokuwiki/do...s:anchor_watch
Simi 60 is offline   Reply With Quote
Old 03-19-2019, 07:30 AM   #9
Guru
 
ranger42c's Avatar
 
City: Maryland
Country: USA
Vessel Model: 42' Sportfish
Join Date: Aug 2013
Posts: 4,157
When we're below, I can't always hear alarms from electronics on our bridge either, and those units take more power than a tablet or cell phone too, so we use tablet/phone apps closer to where we are.

A "survey" of anchor alarm apps:

Best Anchor Watch/Alert/Alarms apps?

I think I did on one cruisersforum.com, too.

-Chris
__________________
South River, Chesapeake Bay
ranger42c is offline   Reply With Quote
Old 03-19-2019, 07:55 AM   #10
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,535
The trouble is that a lot of software gets written by people who never use it. How many of the engineering at Garmin in Kansas do you thing are cruisers? Let along how many have anchored while trying to coordinate setting an alarm mark, let alone figure out how large a circle to set to allow for rode length, scope, and GPS position relative to bow, and over all boat length, let along been waken in the night by an alarm and a dragging anchor.


I haven't tried any of the phone apps because I fundamentally don't trust the phone reception and reliability when it's below deck. But I like the idea of one that uses the boats GPS over wifi. I could get comfortable with that.


So far the two I like, and I use them both together, are the anchor watch in Maretron's products, and the boundary circle in Coastal Explorer. I mark our position on both when the anchor touches down. Both have adjustable position and radius. And both can be wired to speakers that will wake the dead. CE tracks add some more info plotting boat movement and providing an excellent visual indicator of drag as you will see the boat's sweep slowly smearing down wind.


And in addition, I use a VNC (remote computer screen viewer/mirror) to let me watch the Maretron screen bedside on an iPad. My "At Anchor" Maretron screen have the anchor alarm which shows the swing circle and the boat's position and heading, plus weather info, and a bunch of other things I like to watch while at anchor. While sleeping, I can quickly glance over, see what's up, and if all is well, go right back to sleep without waking up too much.


It all works for me, and I have no doubt there are many, many equally good ways to accomplish the same thing.
__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Old 03-19-2019, 08:50 AM   #11
Senior Member
 
JustBob's Avatar
 
City: Bainbridge Island
Country: USA
Vessel Name: Mahalo
Vessel Model: 2018 Hampton Endurance 658
Join Date: Apr 2016
Posts: 433
Quote:
Originally Posted by Simi 60 View Post
Opencpn.

Using mouse, right click > drop mark > set anchor alarm
Grab and drag into better spot if required

https://opencpn.org/wiki/dokuwiki/do...s:anchor_watch
Right.... but I'm not using OpenCpn.
__________________
JustBob
www.mvmahalo.com
JustBob is offline   Reply With Quote
Old 03-19-2019, 08:52 AM   #12
Senior Member
 
JustBob's Avatar
 
City: Bainbridge Island
Country: USA
Vessel Name: Mahalo
Vessel Model: 2018 Hampton Endurance 658
Join Date: Apr 2016
Posts: 433
Quote:
Originally Posted by twistedtree View Post


So far the two I like, and I use them both together, are the anchor watch in Maretron's products, and the boundary circle in Coastal Explorer. I mark our position on both when the anchor touches down. Both have adjustable position and radius. And both can be wired to speakers that will wake the dead. CE tracks add some more info plotting boat movement and providing an excellent visual indicator of drag as you will see the boat's sweep slowly smearing down wind.
Thanks Twisted. Since I have both of these I shall give them a look!
__________________
JustBob
www.mvmahalo.com
JustBob is offline   Reply With Quote
Old 03-19-2019, 09:04 AM   #13
Senior Member
 
JustBob's Avatar
 
City: Bainbridge Island
Country: USA
Vessel Name: Mahalo
Vessel Model: 2018 Hampton Endurance 658
Join Date: Apr 2016
Posts: 433
Quote:
Originally Posted by OldDan1943 View Post
JustBob, I have never figure out how big the circle should be. PLUS, the anchor alarm is of little good if it wont wake you while you are sleeping. I would think there should be a way to extend the anchor alarm to the stateroom or put a bell on the system so you can hear in in the stateroom.
Was thinking about your question and (hard to believe) but college geometry reawakened in my brain and I recall that A squared + B squared = C squared.

If you are in 50 feet of water when you drop, that's A.

You pay out 150 of rode, that's B.

Do the math and that tells you that in theory your boat can only be 141 away from the anchor, max. Of course that will lengthen if the tide lowers, and shorten if the tide raises.

So I would say ignore the calculated value for b, and use how much rode you payed out. Add a fudge factor for some limited movement, tidal change, etc.

So for like this example I think a circle of 200' or 225' should work?
__________________
JustBob
www.mvmahalo.com
JustBob is offline   Reply With Quote
Old 03-19-2019, 09:27 AM   #14
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,535
Quote:
Originally Posted by JustBob View Post
Thanks Twisted. Since I have both of these I shall give them a look!


One thing to watch out for with the Maretron anchor alarm that may not be obvious...... the alarm is only armed when the boat mode is set to “Anchored”. I found this out the hard way, but fortunately no grounding. They have subsequently placed a big “Armed” indicator on the anchor alarm to clearly show the status.
__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Old 03-19-2019, 09:47 AM   #15
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 7,668
Bob
The circle really gets interesting to estimate in a 35' tidal range. In lighter airs our chain tends to move towards the anchor as currents shift and drag the chain every 6 hours. For these and other reasons we prefer a short scope, all chain and oversize anchor.

For our vessel, an anchor alarm powered from a depth sounder has proven much more meaningful than GPS sensing alone. Irregular bottoms - with that not charted high spot looming at low tide - has awoken us more than once.

If the master is far from the data center as is likely in your and TT's case, a Maretron or other unit parked near your bed can have all sorts of data alarmed in whether depth, position, genset status, inverter etc. In some large yachts I've seen a mini control room of data in the Captain's quarters.
sunchaser is offline   Reply With Quote
Old 03-19-2019, 09:48 AM   #16
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,535
Quote:
Originally Posted by JustBob View Post
Was thinking about your question and (hard to believe) but college geometry reawakened in my brain and I recall that A squared + B squared = C squared.



If you are in 50 feet of water when you drop, that's A.



You pay out 150 of rode, that's B.



Do the math and that tells you that in theory your boat can only be 141 away from the anchor, max. Of course that will lengthen if the tide lowers, and shorten if the tide raises.



So I would say ignore the calculated value for b, and use how much rode you payed out. Add a fudge factor for some limited movement, tidal change, etc.



So for like this example I think a circle of 200' or 225' should work?

Exactly, thought the ride length is C, but that’s not the point. The key is that ride length is a very close proxy for swing circle. But I also mentally add the boat length, plus a little for good measure. But with 150’ out, 225 seems like a good circle.

There are other subtleties that he-who-shall-not-be-named, formerly of ActiveCaptain argued because your GPS position is not the actual anchor drop point since your GPS is more midship and your anchor is at the bow. So in one direction that length difference adds to your circle, and in the opposite direction it subtracts. I think he was right about all that, but I also think that it really doesn’t matter unless you are trying to anchor within some small distance of other boats, and we all know that only sail boats do that :-)
__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Old 03-19-2019, 12:28 PM   #17
Senior Member
 
porman's Avatar
 
City: Duvall, Wa
Country: USA
Vessel Name: Beach Music II
Vessel Model: 2003 Mainship 430 Trawler
Join Date: Aug 2014
Posts: 428
I'm still a fan of Anchor Pro on my Android phone. It uses GPS so doesn't need a cell signal. There is no problem maintaining a signal next to my bed. Just remember to set it when you drop the anchor and set the radius of the circle you want. I'm a light sleeper at anchor so I occasionally look over and see how far away from the anchor we are. It even has a nighttime setting so it is easier to see. And the alarm will wake up anyone.
porman is offline   Reply With Quote
Old 03-19-2019, 12:40 PM   #18
Senior Member
 
JustBob's Avatar
 
City: Bainbridge Island
Country: USA
Vessel Name: Mahalo
Vessel Model: 2018 Hampton Endurance 658
Join Date: Apr 2016
Posts: 433
Quote:
Originally Posted by sunchaser View Post
Bob
For our vessel, an anchor alarm powered from a depth sounder has proven much more meaningful than GPS sensing alone. Irregular bottoms - with that not charted high spot looming at low tide - has awoken us more than once.

If the master is far from the data center as is likely in your and TT's case, a Maretron or other unit parked near your bed can have all sorts of data alarmed in whether depth, position, genset status, inverter etc. In some large yachts I've seen a mini control room of data in the Captain's quarters.
First, I really like the idea of monitoring/alarming on the depth. I shall definitely play with this idea.

Second, I have the Garmin GMI-20 in the master stateroom so theoretically I can monitor anything in the Garmin system. I have heard about using it as anchor drag watch but don't know how to do it as of yet. It's a shame the Garmin manuals are so lacking in information.
Attached Thumbnails
Click image for larger version

Name:	gmi20.JPG
Views:	27
Size:	47.0 KB
ID:	86535  
__________________
JustBob
www.mvmahalo.com
JustBob is offline   Reply With Quote
Old 03-19-2019, 12:47 PM   #19
Senior Member
 
JustBob's Avatar
 
City: Bainbridge Island
Country: USA
Vessel Name: Mahalo
Vessel Model: 2018 Hampton Endurance 658
Join Date: Apr 2016
Posts: 433
Quote:
Originally Posted by twistedtree View Post
Exactly, thought the ride length is C, but that’s not the point. The key is that ride length is a very close proxy for swing circle. But I also mentally add the boat length, plus a little for good measure. But with 150’ out, 225 seems like a good circle.
Yes, I typo'd B when I should have said C. But you said "ride" and it's "rode," so brother we are even

Yes, kind of interesting about anchor placement vs where your GPS is. I think it is also likely that when you go to set the hook, you are going to drag it some distance before it digs in.

My Garmin system often reports that I'm WELL outside of the range I should be from my anchor (mark). Like 100 feet.

I got concerned that my chain counter wasn't accurate. That since Garmin is saying the boat is 225' away from the mark, that I really didn't let out 175', I payed out 200+.

So I carefully marked the chain and found that the chain counter is spot on.

So it seems to me the delta in my case could be a combination of the anchor platform vs GPS (which is probably 32-35 feet) and some dragging before the hook takes hold.

Probably if we need a level of precision inside of 50-75 feet we are in the wrong spot?
__________________
JustBob
www.mvmahalo.com
JustBob is offline   Reply With Quote
Old 03-19-2019, 12:57 PM   #20
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,535
Quote:
Originally Posted by JustBob View Post
Yes, I typo'd B when I should have said C. But you said "ride" and it's "rode," so brother we are even

Yes, kind of interesting about anchor placement vs where your GPS is. I think it is also likely that when you go to set the hook, you are going to drag it some distance before it digs in.

My Garmin system often reports that I'm WELL outside of the range I should be from my anchor (mark). Like 100 feet.

I got concerned that my chain counter wasn't accurate. That since Garmin is saying the boat is 225' away from the mark, that I really didn't let out 175', I payed out 200+.

So I carefully marked the chain and found that the chain counter is spot on.

So it seems to me the delta in my case could be a combination of the anchor platform vs GPS (which is probably 32-35 feet) and some dragging before the hook takes hold.

Probably if we need a level of precision inside of 50-75 feet we are in the wrong spot?



"Ride", that's pretty funny. Totally missed it, but I'm good at missing typos, especially my own.


Another factor is GPS accuracy, and 9m is pretty common. So that adds another 30' of slop.


It's just not high accuracy stuff, so counting every detail isn't worth it.


That said, in shallow anchoring I can see how it starts to make more of a difference. Say 8' of water and 30' of chain. Your boat length and GPS error are 3x the rode length....
__________________

__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 08:59 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012