The use of a phone as a GPS in the back country is not only practical, but offers big advantages over a dedicated GPS device.
This page describes the hardware and software that I use. As my phone is Android, I cannot comment on Apple phones.
A good phone for GPS does not have to be the latest. I use the Acer Z630, that was available for $200 in 2016. This phone has a large display. This is a big advantage for use as a GPS as much surrounding terrain is visible, allowing for orientation with respect to neighboring terrain. Other important features are a compass sensor, a good battery and Assisted GPS (A-GPS) which finds satellites more quickly.
Newer phones are now available with better specs. Important for GPS work are a large display (5.5 inch), good battery (4000 mAh), compass, A-GPS, GLONASS (Russian satellites) and even BDS (Chinese satellites).
Advantages of a phone for GPS
- large display - the Z630 has a 5.5 inch (720 x 1280 pixel) display, as compared to the Garmin 60csx which has a 2.6 inch (160 x 240 pixel) display
- fast pan and zoom - much faster than the Garmin 60csx, which redraws the screen each time
- tracks are stored in open source format (.gpx), rather than the Garmin proprietary format (.gdb)
- no need to use special software to retrieve tracks from the device
- the phone is a general use computer, providing a camera, bird apps, flower apps, etc.
- not waterproof - the phone must be kept in a plastic bag and is not easy to use in the rain
- more fragile - must be more careful where it is kept; use a screen protector
The Acer Z630 has a 4000 mAh battery which is large for a phone. I have used it for a full day and returned with 70 percent battery remaining. Additional battery life can be had by turning off wifi and bluetooth (airplane mode).
The phone can be used over a number of days with the use of a power bank, a battery that allows the recharging of phones through the micro-USB charging port. An advantage of the power bank is that it allows recharging without turning the phone off. A power bank is similar in weight to spare batteries for a GPS device.
When tracks are recorded with both a phone and a GPS device, there is little noticeable difference. There is a limit to handheld GPS accuracy, as a group of GPS users will notice when they compare stats at the end of a trip. Canyons and walls especially compromise accuracy, probably due to reflection of the signal.
GPS Phone Apps
I use Backcountry Navigator (BCN), which is quite good. There is a free version and a paid version, so you can try it out for free. I have found Backcountry Navigator to be quite satisfactory so I have not looked at other GPS apps. My only complaint is that it treats routes the same as tracks.
There are numerous GPS apps available, and a variety of map sources. While I have looked at alternatives, I have not done any detailed comparisons. Many apps are deficient in that they lack such basic functionality as creating waypoints.
While Backcountry Navigator can be used by downloading maps before you set out hiking, the better alternative is to use pre-built atlases - basically databases of maps. These can be placed on the phone SD card.
OpenAndroMaps.org provides an excellent set of maps in the form of atlases. If the site is accessed from the phone, it allows one-click downloading of atlases to Backcountry Navigator. Maps are available for Alberta (0.25 GB) and British Columbia (1.4 GB). Best of all, maps are available for virtually all around the world.
One needs to be careful of some maps provided by social media sites as they contain a number of apparent trails which are nothing other than somebodies track through the bush.
The GPS Exchange Format (.gpx files) has become the standard for saving GPS tracks, waypoints and routes. Garmin devices use Garmin GPS Database (.gdb) files. The Keyhole Markup Language (.kml files) is used to define map features, usually in conjunction with Google Maps, and can also be used to store tracks.
Bow Valley Software Tools
Bow Valley Software has a page available - GPX Workshop - for working with tracks, waypoints and routes with storage in gpx files.