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Old 19-09-2014, 13:23   #61
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Re: Anchor Alarms ???

stepping back a bit from anchor alarms specifically . . . I have mentioned before that there seem to be two different philosophies about 'procedure' (with a spectrum between them).

One philosophy is weighted toward lots of routine procedure. The (conventional) military is this way. The other is weighted toward situation and judgement dependent procedure.

You see this with PFD and tether use . . .do you them 'always', or only when your judgement and situation seems to demand them, or somewhere in between?

There is another spectrum of philosophies between those who believe in "KISS and simple', and those who believe in 'full features/functionality'.

Sailors are well scattered along both these spectrum's. I personally am toward the situation and judgement dependent end of the first and the KISS end of the second, but I will never suggest that is the only or the best approach, nor criticize anyone for being elsewhere on the spectrum.

I will not even criticize people who are ignorant of the alternatives and options, but I WILL criticize if they are unwilling to learn or try or work at it (or help others).
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Old 19-09-2014, 14:27   #62
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Re: Anchor Alarms ???

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Originally Posted by transmitterdan View Post
Ted,

GPS in iPhone doesn't require cell service. The anchor alarm apps don't need cell data to know the position has changed. They only need cell data to show your position on Google Earth which some of them do. But they will work as anchor alarms even without cell service
Well, thank you for your response, but I'd like a reliable link that defiantly and reliably confirms this. I have an iPhone 4s which supposedly is meant to have 'GPS' according to some guru's. But I know through experience that once I'm out of phone range, I loose this supposed GPS functionality.

Everything I google trying to work out if it does or does not have true GPS capability seems to indicate it doesn't! It has what some are calling 'Assisted GPS'. I can't seem to find anything from Apple that confirms real GPS, as in accessing the satellite system.

Now, just after posting this I've discovered something directly from Apple, which I think will be more reliable information than someone else simply saying so.

Apple have a help page on all their devices from iOS 4 through to iOS. 7 and under improving location services it says the following.

"Verify that you have a cellular or Wi-Fi network connection. This allows the Assisted GPS (A-GPS) on the device to locate visible GPS satellites faster, in addition to providing initial location information using the Wi-Fi or cellular networks.
Note: Microcells (sometimes called Femtocells) aren't supported with Location Services."

This supports what my experience is. If I get out of cellular range or run out of credit, my location device becomes really inaccurate and more often than not, doesn't work at all.

http://support.apple.com/kb/HT5594
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Old 19-09-2014, 14:35   #63
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Re: Anchor Alarms ???

First off, I apologize if I offended Palarran. The reasoning behind what I said that I think may have offended was "rather than rely on their senses," and I may not have written that clearly enough. I did not mean one should not use anchor alarms, and it certainly is up to each skipper to choose what he or she wants to use and how and when to use it, only that in my experience, the conditions in which one is likely to drag are also likely to awaken one, or to be determined in advance, and one is therefore able to use eyeballs, transits (where present) and other tools, as well.

We do use the anchor alarm on our GPS, and have occasionally also set the depth alarm where we thought it necessary. I guess that puts us in the "it depends on the situation" portion of the sailing behavior spectrum. I think that fatigue would also be a factor in when to use an anchor alarm. I am not now arguing against any use of anchor alarms.

My bias is that I don't have trust for untried by me electronic gadgets. And we see a lot of new cruisers who appear to be over-dependent on electronic stuff. Our way of using anchor alarms has worked for us for on the order of 25 yrs., maybe a little more, and I trust it. I have no objection to anyone using anchor alarms, but then I've never been harassed by someone else's alarm, as was the poster here who started a thread about that.

I'm outta here now, for the time being....

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Old 19-09-2014, 14:40   #64
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Re: Anchor Alarms ???

Ted, iPhone 4 has gps, that's the main one I use for our anchor alarm. It doesn't need a sim cars or wifi connected to operate for anchor alarms or navigation such as navionics. Google maps and earth need a phone or wifi connection
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Old 19-09-2014, 14:52   #65
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Re: Anchor Alarms ???

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Well, thank you for your response, but I'd like a reliable link that defiantly and reliably confirms this.
"All iPhone models (4, 4S, 5, 5C, 5S) include a GPS chip. The 4S and all 5 models also support GLONASS which in some locations should improve accuracy and time to first fix."

How to use the iPhone 4 as a GPS mapping device for backpacking
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Old 19-09-2014, 15:13   #66
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Re: Anchor Alarms ???

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"All iPhone models (4, 4S, 5, 5C, 5S) include a GPS chip. The 4S and all 5 models also support GLONASS which in some locations should improve accuracy and time to first fix."

How to use the iPhone 4 as a GPS mapping device for backpacking
That's hardly an authoritive link! There are lots of people saying the same thing. But is it accurate? Is it true? I know it's a common idea that if it says so on the web, then it must be accurate, but I'm a little more skeptical than the aliensaretrue.com references.

I've just sat in my lounge room, about 4 miles from a Telstra cell tower (that's our most reliable ones), and did a little experiment. At my location I seem to have excellent gps location services on for example my Navionics app. I then pulled the sim out, rebooted, and all of a sudden it's having trouble finding where I am. I went outside just to make sure the house was not interfering. Nothing. I put the sim back in, and picks it up immediately.

This seems to me to again confirming just my 'experience', once I get out of cell range the gps reliability his highly suspect, if it even works at all.

But, according to the following 'APPLE' link, you can improve gps accuracy by ensuring your in either wifi or cell range and/or have credit. Which is indicating what?

iOS 7: Understanding Location Services
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Old 19-09-2014, 15:15   #67
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Re: Anchor Alarms ???

GLONASS looks helpful, it's now operational, as long as we can trust the Russians?
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Old 19-09-2014, 15:17   #68
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Re: Anchor Alarms ???

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Originally Posted by estarzinger View Post
I personally am toward the situation and judgement dependent end of the first and the KISS end of the second, but I will never suggest that is the only or the best approach, nor criticize anyone for being elsewhere on the spectrum.
An interesting topic. I agree with the KISS philosophy especially in boat design and equipment. I think with minor differences our views are very close. I also agree with situation and judgement dependent type of decision making, but in some areas we would make very different decisions.

Our views on anchor alarms is a good example:

I have dragged in less than 10knots of wind. While it was an unusual situation (the anchor buoy caught around the stern ladder and tripped the anchor). I have seen swivels snap, and even anchors drag because someone forgot to to put the bolt in a Kobra anchor. My view is that while the above mistakes can be avoided there are other traps that could potentially cause a drag in light wind.

I am not as confident as you that I would always wake when dragging particularly with a slow drag where the boat does not turn beam on to wind.

I also find (perhaps because of differing equipment) that with a normal anchor alarm false positives are almost non existent.

One major distinction concerns whether the "rule" is made by an outside agency. If the government, or my insurance company, mandated the compulsorily use of an anchor alarm in all conditions that would be following "routene procedure".

On the other hand if it my judjment that the anchor alarm should be used because I feel the advantages (warning me of dragging) outweigh the drawbacks (a slight increase in electricity consumption) I would argue that it is more along the lines of judgment call. The only difference is the threshold. My criteria is the anchor must be down and wind must be 0 knots or above
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Old 19-09-2014, 15:27   #69
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Re: Anchor Alarms ???

Quote:
Originally Posted by estarzinger View Post
"All iPhone models (4, 4S, 5, 5C, 5S) include a GPS chip. The 4S and all 5 models also support GLONASS which in some locations should improve accuracy and time to first fix."

How to use the iPhone 4 as a GPS mapping device for backpacking
Battery life is the downfall of all iPhones for these apps. If you charge it to full right before you turn in, it might make it all night. Additionally, in numerous side by side trials, the accuracy of my wife's iPhone GPS is not as good as either of my Android phones or my Nexus7 tablet. This includes on the boat, in the car or sitting at home. My S4 will easily go 36 hours on the boat even if not turned off at all. We relegate the iPhone to phone calls home for which it is well suited. I have seen the iPhone locate my wife 3\4 of a mile away when she's right in front of me.
My theory is that Google is more motivated than Apple because GPS location is a more important part of their business than is the case with Apple. Either way an anchor alarm is a safety backup for the boat and crew. Whatever you use, (I cross check all dark of night alarms with my plotter on max zoom) it needs to be accurate.
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Old 19-09-2014, 15:34   #70
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Re: Anchor Alarms ???

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But, according to the following 'APPLE' link, you can improve gps accuracy by ensuring your in either wifi or cell range and/or have credit. Which is indicating what?
"Assisted GPS" is a poor and confusing term. It normally means the device has a proper GPS chip, but can also use the phone signal to triangulate a position.
This is superior to a "normal" GPS.

In situations such as inside a high rise building phone signal triangulation can speed up the initial fix and may in fact provide better position information than the GPS. (The GPS signal is weak and can easily be blocked indoors) Once outside the GPS position will be far more accurate. The device will no longer use the phone signal triangulation (although sometimes it can still speed up the initial fix)

The situation is particularly confusing because some devices do not have the GPS chip and just use phone signal triangulation.

I can confirm that my ipad2 and my android phone both have proper GPS chips and will work as a normal GPS outside the phone coverage areas. (Not all iPads have this). These are both listed in the specs as having AGPS or "assisted GPS"

I don't know the iPhone models, but from what others are saying your phone should be the same.

Sometimes these problems occur because the GPS is not turned on, or the app you are using does not have permission to use the GPS information. Of course it could also be a hardware, or software fault with the GPS chip leaving the phone to manage with only the phone signal position information.
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Old 19-09-2014, 15:40   #71
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Re: Anchor Alarms ???

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Originally Posted by tedsherrin View Post
That's hardly an authoritive link!
well I don't know what you consider 'authoritative':

How the iPhone knows where you are | Macworld

How the iPhone GPS differs from a standalone navigation GPS
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Old 19-09-2014, 16:24   #72
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Re: Anchor Alarms ???

Quote:
Originally Posted by tedsherrin View Post
.........

I've just sat in my lounge room, about 4 miles from a Telstra cell tower (that's our most reliable ones), and did a little experiment. At my location I seem to have excellent gps location services on for example my Navionics app. I then pulled the sim out, rebooted, and all of a sudden it's having trouble finding where I am. I went outside just to make sure the house was not interfering. Nothing. I put the sim back in, and picks it up immediately.

This seems to me to again confirming just my 'experience', once I get out of cell range the gps reliability his highly suspect, if it even works at all.

But, according to the following 'APPLE' link, you can improve gps accuracy by ensuring your in either wifi or cell range and/or have credit. Which is indicating what?

iOS 7: Understanding Location Services
I tend to share Tedsherrin's concern. As an example, I found that when using a friend's iPhone 5, the inbuilt compass was inactive unless the phone was picking up an active 3G signal. There didn't seem to a logical reason for this. The best explanation I could work out was that it needed a location in order to know the local magnetic variation but even so, the position should have been available from the GPS chip...

So I remain doubtful of many claims about phone location services outside cell or wifi coverage and thus also doubtful about using such services as anchor alarms; I am happy to be proven wrong
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Old 19-09-2014, 16:36   #73
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Re: Anchor Alarms ???

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By 'authorative' means a reliable source, not a review or Macworld! the manafacturer for example is always a good source.

Your second article is a good one, and it's summary states, "The iPhone’s GPS us very good. Without extra software, however, iPhone navigation is entirely dependent on the Internet", my emphasis exactly.

My main point is, going to sleep and relying on an 'app', that depends on cellulor connection is not what I'd be doing. Risking my boat and possibly the lives of my family on something that is clearly not accurate at sea.
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Old 19-09-2014, 16:54   #74
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Re: Anchor Alarms ???

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I have dragged in less than 10knots of wind.
How many times a year, or a decade, do you drag?

I am always a bit surprised at anchor and related threads because for us it is just not a problem. When we were "world cruising" on hawk with the big Bruce we dragged once in a decade (Albany, SW Australia) and then we knew full well that we were going to drag because of the bottom. When we were experimenting with other (next gen) anchors we dragged about once a year, always (except once) in situations where we knew there was a risk (because of heavy kelp or rock or such). And on silk RTW we never dragged - had trouble getting a good set sometimes but never dragged after being satisfied with the set.

Quote:
Originally Posted by tedsherrin View Post
By 'authorative' means a reliable source, not a review or Macworld! the manafacturer for example is always a good source.
.
Look . . . I have used both iPhone and iPad navigation 1000nm out at sea. They worked, they very definitely have GPS Chips. But if you want to believe yours does not, that's just perfectly fine also.
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Old 19-09-2014, 17:22   #75
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Re: Anchor Alarms ???

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.............. I have dragged in less than 10knots of wind. While it was an unusual situation (the anchor buoy caught around the stern ladder and tripped the anchor). ..........
I came close to that once. I was told of a trick and set my buoy up for it but haven't tried it yet.

Instead of tying the trip line to the buoy, run it trough the buoy (this assumes a ring of some sort on the buoy) and small weight to the end. The weight will keep the line pretty much vertical over the anchor. Of course it's important that the weight be small enough not to trip the anchor loose.
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