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Catalina/Capri 25/250 Sailor's Forums

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Droid Anchor Alarm

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britinusa
Web Editor

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USA
5404 Posts

Initially Posted - 12/02/2012 : 06:32:20

Found several anchor alarm apps for android.

Any recommendations?

I always set our handheld gps anchor alarm, but it's a pain to see on the small screen in the middle of the night, plus we have to leave the gps plugged in so it's restricted to the galley area.

Paul

Joint Decision. (Sold)
PO C250WB 2005 Sail # 841.

Moved up to C34 Eximius

Updated August 2015

Edited by - on

redviking
Master Marine Consultant

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USA
1771 Posts

Response Posted - 12/02/2012 : 16:09:03

Not sure which one I grabbed. Shows anchor... Works well.

Sten

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 12/03/2012 : 12:22:13

Depends on how dependable the gps in your phone/tablet is. After that, I don't see why one is better than any other. Unless it crashes your phone. That could be problematic.

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britinusa
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Response Posted - 12/03/2012 : 16:31:31

I tried one out for Free, sucked! It would show that we moved over 100' while the tablet was sitting on the dining table at home. Other features looked good: Ability to send a text msg if the scope was exceeded, run in the background, and many more features but in the paid version.

If it's the tablet that is unstable as far as GPS is concerned, agreed! no GPS app will work well.

The handheld wins at this point. But I only tried one app so far.

Paul

Edited by - on

glivs
Admiral

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USA
836 Posts

Response Posted - 12/03/2012 : 18:29:57

Two questions.
First...what has been your experience with anchor alarms?....I can see the potential but just have not realized much benefit using my handheld GPS. A big advantage of our shallow draft (wing) is that we can go inside most of the big boys to get the most shelter from the shoreline if needed. Anchoring in 15+ ft our issue is that the distance to shore in many anchorages does not leave much tolerance for dragging which conflicts with a large swing diameter when the boat is hunting or the winds are shifting 180 as a front passes through. This is precisely, however, when we would like an alarm as our shorelines are mostly very unforgiving.

For the techno savy....how does smart phone GPS technology compare to handhelds? Sure anyone can calculate coordinates but dedicated GPS units (variable with price) take advantage of a lot of tricks to improve accuracy, reliability and speed of acquisition, including optimized electronics, simultaneous vs. sequential receipt of multiple signals and optimized algorithms, e.g., to use information on the carrier frequency, reduce multiple reflections and even management of round off error...And no I'm not talking about survey quality instruments. Anyone seen any tests comparing the two technologies?

Edited by - on

britinusa
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Response Posted - 12/03/2012 : 18:43:45

Q1: Our sailing ground (excuse the pun) is Biscayne Bay. Skinny around the edges where we anchor. By skinny, I mean less than 6' is normal.

With a scope of 7 to 1, we should pay out 42' of line but typically run out at least 50.

So we have an area that is 100' in diameter, and we anchor about 1/2 mile off shore.

So there's not a lot of room to drag going to shore. North and South drag is no big deal if the anchorage is empty, but that's not the norm and sometimes the other boats drop the hook less than 200' from us and other boats.

Consequently, I set the handheld anchor alarm limit to the scope. This means we hear the alarm if the boat swings due to a wind shift, or current shift if light winds.

I would rather wake up several times during the night and go check if we are dragging or swinging rather than risk dragging 100'+ before the alarm. That could (and has) ended up having to make good on the drag at OhSillyHour.

Does that make sense?

Q2: That was the idea of installing an app or two. But didn't want to waste time testing on the water if it doesn't perform inside the house!

Paul

Edited by - on

redviking
Master Marine Consultant

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USA
1771 Posts

Response Posted - 12/03/2012 : 20:50:10

I downloaded this one... https://play.google.com/store/apps/details?id=de.meditgbr.android.anchoralarm&hl=en

accurate on my droid...

gps should be gps, accuracy is set by the feds.

I like this flag keyboard https://play.google.com/store/apps/details?id=net.traduku.FlagKlavaro&feature=also_installed#?t=W10.

sten

Edited by - redviking on 12/03/2012 20:53:06

Stinkpotter
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Djibouti
9076 Posts

Response Posted - 12/03/2012 : 21:16:16

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by redviking
 ...gps should be gps, accuracy is set by the feds...<hr height="1" noshade id="quote"></blockquote id="quote">Do smartphones utilize WAAS?

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Voyager
Master Marine Consultant

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5352 Posts

Response Posted - 12/03/2012 : 22:40:52

Good question Dave.
WAAS will increase your accuracy/reduce error from 33 ft down to single digit feet. So that could be one cause of inaccuracy of your smartphone.
I don't know about your GPS but if I try to get a fix inside my house I get an excuse:
"GPS was unable to receive a usable satellite signal!
Reorient the receiver or if inside, move to a location outside the building!"
Somehow wood, carpets, shingles interfere with reception.
Lastly, GPS uses a set of successive approximations when acquiring a signal, so over time as the receiver continues the acquisition process, accuracy improves. If I try to set a waypoint during this period my GPS will get my position wrong 10 times out of 10.
Have you tried the app out on your patio or garden table after the app has finished acquiring.

Edited by - Voyager on 12/03/2012 22:42:50

rrick
Captain

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USA
261 Posts

Response Posted - 12/03/2012 : 23:08:25

I noticed you said "we." Smartphones have alarms :) More guests, shorter the watch hour (up to eight, traditional).

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Prospector
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Canada
3159 Posts

Response Posted - 12/04/2012 : 07:45:23

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by redviking
 I downloaded this one... https://play.google.com/store/apps/details?id=de.meditgbr.android.anchoralarm&hl=en

accurate on my droid...

gps should be gps, accuracy is set by the feds.
sten
<hr height="1" noshade id="quote"></blockquote id="quote">

Differing opinion here. I find that my tablet drops the GPS signal in a most amazing manner. Its really a big deal for me. If I set teh car navigation up before I leave home, for a trip to toronto, I usually lose GPS within 10 minutes, and won't regain it for at least half an hour. Absolute junk.

The tablet wants to switch to cell signal to triangulate its position, and will kick out a message that it has no cell signal since I don't have a data plan.

When it is working, It is usually accurate to within 10 feet.

I don't trust the GPS at all in this thing. GPS is not the same in all devices.

Edited by - on

Dave5041
Former Mainsheet Editor

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3758 Posts

Response Posted - 12/04/2012 : 10:19:28

Location is key. My Iphone has no problem in the cabin with only fiberglass to contend with. I usually put it on the dash when driving, but it works pretty well on the console. Accuracy is about the same as my Garmin Nuvi and Etrex. The Etrex has better sensitivity in marginal locations

Edited by - on

glivs
Admiral

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USA
836 Posts

Response Posted - 12/05/2012 : 07:45:31

<blockquote id="quote">quote:<hr height="1" noshade id="quote"> gps should be gps, accuracy is set by the feds. <hr height="1" noshade id="quote"></blockquote id="quote">
Short answer: no; otherwise GNSS would be of no use in surveying or research. Correct answer: On open water where 5 to 10 m accuracy is all that is required I suspect different units will yield similar position estimates. Getting a position estimate, however, is only part of the issue. For example, dedicated units typically provide information on the estimated accuracy of position estimates (I don't know about smart phone apps). Although we are in a WAAS environment, we sometimes see uncertainty in position estimates as large as 30m (100') because for that 10 min. window, the satellites are poorly aligned for our region. Who cares if I'm just tracking my path but if I'm anchored 150m off a rock shoreline with a 40m scope, that 30m uncertainty makes a difference to me and my anchor alarm. I always average my anchor position but even then, uncertainty remains. My old Garmin 76 provided an accuracy estimate on the averaged position; my Oregon 450 does not. If headed out for the weekend I now often check configuation using [url="http://www.trimble.com/planningsoftware_ts.asp"]Trimble planning[/url] software. Overkill, but easy to do.

Off the water, huge difference between units. In hiking in the local foothills my old Garmin 76 would almost always acquire a position estimate within a minute or less. I've left my Oregon sitting beside the 76 for 10's of minutes without it ever locking on sufficient no. of satellites to get a position.

Edited by - on

GaryB
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4303 Posts

Response Posted - 12/05/2012 : 19:22:44

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by glivs
 <blockquote id="quote">quote:<hr height="1" noshade id="quote"> gps should be gps, accuracy is set by the feds. <hr height="1" noshade id="quote"></blockquote id="quote">
Short answer: no; otherwise GNSS would be of no use in surveying or research. Correct answer: On open water where 5 to 10 m accuracy is all that is required I suspect different units will yield similar position estimates. Getting a position estimate, however, is only part of the issue. For example, dedicated units typically provide information on the estimated accuracy of position estimates (I don't know about smart phone apps). Although we are in a WAAS environment, we sometimes see uncertainty in position estimates as large as 30m (100') because for that 10 min. window, the satellites are poorly aligned for our region. Who cares if I'm just tracking my path but if I'm anchored 150m off a rock shoreline with a 40m scope, that 30m uncertainty makes a difference to me and my anchor alarm. I always average my anchor position but even then, uncertainty remains. My old Garmin 76 provided an accuracy estimate on the averaged position; my Oregon 450 does not. If headed out for the weekend I now often check configuation using [url="http://www.trimble.com/planningsoftware_ts.asp"]Trimble planning[/url] software. Overkill, but easy to do.

Off the water, huge difference between units. In hiking in the local foothills my old Garmin 76 would almost always acquire a position estimate within a minute or less. I've left my Oregon sitting beside the 76 for 10's of minutes without it ever locking on sufficient no. of satellites to get a position.
<hr height="1" noshade id="quote"></blockquote id="quote">
It's all about the type of antenna, the strength of the receiver, the alignment of the satellites, and how clear of a shot you have from the satellite to the antenna.

Most (not all) hiking type GPS units seem to have an antenna and receiver that are optimized to pull in a signal even when under trees.

MY HTC phone is not WAAS enabled and has only OK accuracy. My Garmin GPSMAP 378 is WAAS enabled and fluctuates between 7 and 9 feet accuracy on a constant basis.

Edited by - on

redviking
Master Marine Consultant

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USA
1771 Posts

Response Posted - 12/06/2012 : 11:59:30

My HTC when running the Droid anchor alarm ap will set the alarm off while moving the phone down below when set for a couple of meters. As a plotter, using Navionics it was just as accurate as my Garmin. Had to do a night time icw transit after the Xmas parade, and let me tell you it was driving while blind here. No lit markers for miles.

Sten

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Stinkpotter
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Djibouti
9076 Posts

Response Posted - 12/06/2012 : 14:32:02

That's when you want radar--to tell you where the next marker really is.

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piseas
Former Treasurer

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USA
2017 Posts

Response Posted - 12/06/2012 : 16:18:00

Paul, I have Iphone and use Drag Queen. Dont know if android available. But its accurate.
Steve A

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redviking
Master Marine Consultant

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1771 Posts

Response Posted - 12/06/2012 : 20:24:24

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 That's when you want radar--to tell you where the next marker really is.
<hr height="1" noshade id="quote"></blockquote id="quote">

Pilings, no reflectors... Not a lot to get a ping from.

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PCP777
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1225 Posts

Response Posted - 12/08/2012 : 11:28:39

Going to try Drag Queen for Android.

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