The JMT (John Muir Trail) does not have cell service for about 98% of the 211 mile trail, common to any hikers doing hiking in remote mountains.

The Iphone is a great multi-purpose device but up to and including the Iphone 4, if you had GPS on, you also minimally had search-for-Edge cell service on (which drains the battery as there is no cell service, so the phone would keep on searching, draining...).

Anyone on the board have an Iphone 4s? I've hated the fact my Iphone 4 does not allow me to have the GPS on without at the same time having Edge search on (I could turn 3G search off but not Edge). This looks like I can turn off all cellular data services-only off and keep the GPS working. Does anyone on the board have a Iphone 4S and can they confirm? I love having the GPS feature on only for times when you want your photo to have the GPS location tags embedded in the photo, and when you're doing passes full of snow for miles. (Otherwise, I'd want the GPS search off.) I have complained to Apple numerous times, maybe they've listened. Anyone know for sure? Ps, do you know about the JMT Harrison map app for the Iphone?

See the article about this:
http://www.engadget.com/2011/10/15/iphone-4s-lacks-enable-3g-switch/
Link

I seem to recall with my girlfriend's iPhone4 that the GPS still works after turning "Cellular Data" off, it was just A) slow to make a GPS lock without the assistance of cell towers and B) unable to load maps in Google Maps. IIRC you can also use the GPS without any cellular connection by removing the sim card but both methods require a mapping app that stores maps on the phone itself instead of being downloaded from the internet.
Beyond that there was a thread recently about the 4S and the consensus seemed to be that it was heavier and had less battery life than the 4 and so wasn't that attractive.

On the iPhone 4 you can lock the SIM card by setting a password. Go to Settings> Phone > SIM PIN. Set this to 'ON' and setup a password. Now when you next restart your phone it will prompt you to unlock the SIM card. Hit 'OK' [ to continue without unlocking] and all the other phone functions will work normally-BUT without the SIM card on- So no phone calls can be made and no searching for cell towers and no drain on the battery. If you need to make a call you will be prompted to unlock the SIM card- enter the password and it will unlock the card and start the call. Doing this in combination with turning of Data, and WiFi greatly extends battery life for a multi-day trip.

I'd want any GPS I take hiking with me to be waterproof. Is there a waterproof case available for the iPhone? I know some of Garmin's GPS's are waterproof.

I've seen waterproof cases for the iPhone, but they are big and heavy.

Every hiking Garmin is waterproof.

FWIW, I have the 4 (not 4s), and have the same menu item to turn off cellular data. I'll try using my TomTom tomorrow with the cellular data off and let you know if it works.

Yes, there is. The SealLine iSeries cases are relatively light and are waterproof. My iPhone 4 fits perfectly in the small one and has worked great on several trips, including two weeks in wet Alaska. The case weighs 1.1oz on my scale but the new ones (slightly different design) are 1.6oz.

BTW: The Verizon iPhone 4 works fine with cellular data and WiFi off, it just burns up the battery looking for a CDMA signal at full power since the GPS does not work in Airplane mode due to being part of the cellular transceiver section.

Edited by radio_guy on 10/15/2011 20:43:59 MDT.

Here's our article about using iPhone as Backpacking GPS/Mapping device with some critical information about maintaining battery life.

In particular, with the iPhone 4, your comment "if you had GPS on, you also minimally had search-for-Edge cell service on" is not true for the ATT version of the iPhone, but is true with the Verizon version. In the ATT version iPhone4 you can disable the phone while leaving the GPS enabled, and are thereby able to get background battery drain down to the range of 1% per day.

I haven't updated the article with info about the iPhone-4s yet, but will do so when I get 4s info about disabling the phone without disabling gps. If you know anything or learn anything about this, please let me know so I can update the article!

I am maintaining an annotated list of iphone gps apps with info about all the apps I've found. If you know of apps that I've missed, or know of important updates that make my comments inaccurate, please PM me with the info, or just reply to this thread.

Thanks, AmyL

Edited by drongobird on 10/30/2012 17:33:36 MDT.

As far as I know you can update the phone's OS and have the software features of the 4S. My son updated his (AT&T). Then you could check for yourself. If it works you don't need to buy a new phone.

Has anyone any experience with these:

http://www.lifeproof.com/lifeproof-store/apple-cases/iphone-4

(Dust, water, etc.-proof and claimed to be 28 grams.)

Lifeproof box. I've got a buddy with one. He likes to drop his under water all the time now, but he says it is sometimes hard to hear people when talking with it on the phone.
Of course if you're on trail then that doesn't matter .

There are videos on youtube where they are snorkeling with the phone while using it as a video camera. Pretty cool.

I guess I'm confused. The GPS feature needs data service to use, since the maps need to be loaded. It doesn't make sense to have a blank screen with a blue dot. Maybe I'm missing something here...

Paul S - please read the article about using iPhone as Backpacking GPS/Mapping device- it will answer your question about using iPhone as a GPS device for backpacking.

From that article - "The method for using the iPhone for backpacking is to use apps that let you preload the appropriate maps and data files over WiFi. When you are out on the trail without cell service, you can use the preloaded maps along with the iPhone’s GPS."

Edited by drongobird on 11/01/2011 17:42:29 MDT.

I used an AT&T iPhone 3GS on the CDT this summer. I jailbroke it so that I could have access to a "Turn Phone off" button, which leaves the GPS on but keeps it set to "No Service" without wasting battery. I was easily able to go a week without charging, as long as kept it to only a few GPS checks a day.

I just used a LokSac baggie to keep it waterproof.

Honestly though, I think the perfect GPS for the JMT is your brain, a compass, and some maps. I found the parts of the JMT I've walked (the PCT) to be generally well marked. I doubt you could get lost enough to justify the weight of a GPS.