GPS on iPhone

[trapezeartist]

Instead of buying a handheld GPS, I decided I could use SWMBO's iPhone as a backup GPS in case the chartplotter goes down. The idea is, in the event of losing the chartplotter, I can read coordinates off the iPhone and plot them on to paper charts. The snag is that the app I am using gives the coordinates google-style in decimals of a degree, so it would need a lot of calculating to convert to degrees and decimals of a minute.

Is there a different app that outputs coordinates directly in the conventional marine notation? There are zillions of GPS apps available but after reading up on about 20 of them I was starting to lose the will to live.

 

[Monique]

Lose the will to live??

My iPhone displays degrees, minutes and seconds. This is through the "Compass" header. Unless you are in fog entering a narrow estuary, there is not much use for better accuracy... IMO of course

 

[grumpy_o_g]

There's no compass in an iPhone 3G - it wasn't added until the iPhone 3GS - so that may be the source of the confusion. A word of warning - the iPhone is about the least water resistant piece of electronics ever created - it even has tell-tales inside it that change colour if they get wet. The first thing an Apple "technician" will do if (when?) they get their hands on your iPhone is peer down the headphone jack to see if it's still white at the bottom. If it's not your next movement should be to reach for your wallet as all bets (including Apple's insurance) are off it's turned red. I would very strongly recommend an aquapac or something similar to protect the iPhone.

For backup position you could just use the Navionics chart app - £15 but it gives you all the UK region charts on your iPhone and is surprisingly usable. It will give your lat/long but you could just as easily use the app itself as a backup and it will gives you tides, let you input waypoints, etc. just like any other basic plotter. It's a little slow on an iPhone 3G but definitely usable.

If you still want to go ahead I'd recommend digging in your pockets and splurging 99c for Travelling Companion. It has a GPS "Compass" (i.e. it derives your course from your position history, as do ALL so-called compass apps for the iPhone 3G) the compass "flips" on touch to show a small map street level map of where you are. It also give Lat and Long in DMS or decimals of a degree. It will also attempt to gives altitude and a postcode and address and that's it. The only downside it that it only works in landscape. If you tilt the 'phone tot he vertical then it switches to show settings. I know they're vertical in the piccies below but that's just the way the website showed them and I'm too lazy to copy them to Photobucket and rotate them and then paste the links - sorry.

It's very fast compared to loading up Google maps or the Navionics app and is great to use when for walking round bits of of a town or city you don't know - it seems to get most use from me when trying to follow directions to a pub in London actually. The screenshots above must be from an iPhone 3GS - the compass defaults to North when the speed is 0mph on an iPhone 3G.

 

[Monique]

I learned much from your post Grumpy OG.

Thanks

 

[gregmlucas]

Boatie

...for less than a fiver has a basic GPS wihich gives position in degrees | minutes | decimal plus a range of built in waypoints - certainly covers the Solent but not sure about other areas.

I bought it for the weather which has general synopsis | inshore waters (and will remember your area) | five day synoptics.

Excellent value

 

[Bosun Higgs]

There's been a bit of debate on here about how well the IPhone GPS will work at sea, particularly offshore when It cant get part of the fix from the phone system ie its working purely as a gps. Something to do with the obviously limited aerial it can be equipped with.

Basic full on GPSs are available for around £100. You can probably get a second hand one for £30. What's your neck and your families worth?

 

[MoodySabre]

How accurate is "GPS" on an iPhone? Doesn't it arrive at your position by triangulating from phone masts rather than from satellites.

I see from Travelling Companion above that 50 metres is quoted - that sounds a huge amount for inshore pilotage.

 

[Phoenix of Hamble]

iPhone 3GS has a proper GPS built in... it doesn't use phone network triangulation. It does however use the network to get an initial approx fix to improve GPS 'lock' time.

This can cause probs at sea, as firstly the GPS fix takes longer, and secondly, the attempt to find a non existent cellular network can kill the batteries.

 

[l'escargot]

How accurate is "GPS" on an iPhone? Doesn't it arrive at your position by triangulating from phone masts rather than from satellites.

I see from Travelling Companion above that 50 metres is quoted - that sounds a huge amount for inshore pilotage.

Mine has just given me a fix within about 10 to 15 feet.

 

[trapezeartist]

Basic full on GPSs are available for around £100. You can probably get a second hand one for £30. What's your neck and your families worth?

Fair point, BH, but at the moment my sailing is very limited in its distance from home waters. So generally, if the main GPS goes down, I can probably pinpoint myself pretty accurately with the Mark One eyeball. The iPhone is the bit of string to back up the belt and braces. When I travel further afield, I will be looking to a proper (cheapie) GPS for my first line of back up. And if I manage further afield still, I'll have to learn the astro stuff.

 

[Bosun Higgs]

In which case, can I recommend the 3 point fix and the exercise of those skills you learned on your nav course.

 

[Stu Jackson]

I...gives the coordinates google-style in decimals of a degree, so it would need a lot of calculating to convert to degrees and decimals of a minute.

Not really, all you have to do is work up a simple spreadsheet from 0 to 60 with reasonable intervals.

D/M/S CONVERSION TABLE
Minutes in decimal Minutes in seconds
i.e. 37d 55.25m = 37d 55m 15s
=(+Ax*60)

 

[mcframe]

iPhone 3GS has a proper GPS built in... it doesn't use phone network triangulation. It does however use the network to get an initial approx fix to improve GPS 'lock' time.

This can cause probs at sea, as firstly the GPS fix takes longer, and secondly, the attempt to find a non existent cellular network can kill the batteries.

Fair point - I wonder whether my iPhone can get a fix before my (non-tinfoil-wrapped) old emergency Garmin eMap can update it's almanac and get it's fix.

I don't think I've fired it up since I bought (but didn't fit) some lithium AAs for it 5 years ago....

 

[dunedin]

Not really, all you have to do is work up a simple spreadsheet from 0 to 60 with reasonable intervals.

D/M/S CONVERSION TABLE
Minutes in decimal Minutes in seconds
i.e. 37d 55.25m = 37d 55m 15s
=(+Ax*60)

Agree - its a cinch, and the i-phone will have an inbuilt calculator so don't even need spreadsheet.
I bought a Nokia N95 on this basis a few years ago (pre-Iphone 3G) - gives GPS, maps, calculator - plus MP3 player, camera - oh and even can use for calls

 

[pau1gray]

Instead of buying a handheld GPS, I decided I could use SWMBO's iPhone as a backup GPS in case the chartplotter goes down. The idea is, in the event of losing the chartplotter, I can read coordinates off the iPhone and plot them on to paper charts. The snag is that the app I am using gives the coordinates google-style in decimals of a degree, so it would need a lot of calculating to convert to degrees and decimals of a minute.

Is there a different app that outputs coordinates directly in the conventional marine notation? There are zillions of GPS apps available but after reading up on about 20 of them I was starting to lose the will to live.

Ok - if you are willing to ignore the anti-iphone brigade and still want to continue then search for NavigX Lite which is free and will report the positions in H DD MM SS.SSSS and is free - hope this helps - there is also a utility called GPS Utility (costs £1.79) which can give you your position in a number of different formats