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The ubiquitous term ‘GPS’ can refer to:
- The Global Positioning System of orbiting satellites, the basis of a highly accurate digital navigation system.
- Part of a device (eg a function on a mobile phone)
- A device (e.g. a handheld or vehicle mounted GPS unit)
The section discusses the use of a mobile phone for bush navigation.
* a mobile phone is also referred to as a smartphone.
Route choice must be the bushwalker’s decision
When using a mobile phone or handheld GPS for bush navigation, there is an important difference compared to using these devices for road based navigation.
A very familiar feature of a mobile phone or vehicle GPS is the device’s capability to show the best road or public transport route to a destination, which is usually accurately specified by a street address.
In the bush, away from roads, until recently the map on a mobile phone or handheld GPS could not show a ‘best’ route, or indeed any route at all other than a straight line. However, Google Earth on a mobile phone and newer model handheld GPS unit will now show a walking route between two points.
Any “suggested” walking route shown on Google Earth or a GPS device must be taken with a grain of salt. The suggested route may be far from the ‘best’ route, and may not even go to the required destination.
Google Maps warns: “Use Caution – walking directions may not always reflect real world conditions.”
The decision about the best route needs to be made by studying any track notes and the paper map, and comparing that with the route shown on the mobile phone or handheld GPS map screen. Tracks may be different, and the destination shown on the device may be incorrect. The small screen, especially on a handheld GPS, is a limitation. It is much easier to see the ‘big picture’ and route options on a paper map.
Backups
Even with full mapping on an electronic device, a paper map (and compass and knowledge to use them) are essential, at least as a backup. A device might fail, get lost or be damaged. The batteries may go flat; more likely if the trip is unexpectedly longer than planned.
No technical detail or instructions
This section describes the range of options for using mobile phone for bush navigation.
“How to” technical instructions on various functions are not provided. The range of mobile phones and phone apps make this impossible.
Instructions for any particular function, app or device can be readily found on the Internet.
Using a mobile phone for navigation
There are several ways a mobile phone with its built in GPS and maps can be used for bush navigation. They are listed here from the most basic to the more complex.
1. Google Maps
A Google map of the area of a trip can be downloaded to the device prior to the trip. This ensures the map is available in areas with no phone coverage. It also greatly reduces battery drain, as the phone can be used in flight mode on the trip, as a data connection is not required anyway.
When downloading a Google map area, only the selected view, of the 3 view options is downloaded. Terrain view, which includes contours, is generally the best. For some trips the satellite view will also be useful.
Offline Google maps are very large files, so the phone will need sufficient storage capacity.
As with all aspects of bush navigation, practice and experimenting is necessary to make the best use of Google maps on a mobile phone.
North Up
Generally the map is easiest to read if north is at the top of the screen. When using two fingers to zoom in and out, it is easy to accidentally twist the map slightly each time, moving it to well off north up, which can confuse be confusing. Tapping the small compass symbol at top right of the screen will return the map to ‘north up’.
2. GPS app
Install a GPS app. There are many alternative apps, with a wide range of features.
The main elements of any GPS app are a compass and the current location. The location will be a latitude and longitude; not useful for bushwalking.
The coordinate format can be changed to UTM, so the location will be shown as a 13 or 14 figure grid reference. With a small amount of instruction and practice, this long grid reference can be read as a ‘traditional’ 6-figure grid reference; useful for finding the location on a topographic map.
3. Mapping apps
Install a Mapping app, e.g. Avenza or Terra Map (2019).
There are two aspects of a mapping app to consider:
- the app itself; do its features and operation suit the user.
- what topo maps can be downloaded and used with it, and at what cost? Generally, (free) base maps lack sufficient detail for bushwalking.
On-line maps are of limited value as a data connection is required to access them.
Mapping apps are sophisticated software that may suit the more technically minded users. They are not so intuitive to use, and lots of practice is needed to develop the familiarity needed to use them well.
As with a handheld GPS, waypoints, routes and track logs can be saved, manipulated, downloaded and uploaded.
The occasional user is better to stick to Google maps.
Advantages of using a mobile phone as a GPS
- Most people own one and are familiar with its operation and settings
- No need to purchase and carry an additional piece of equipment device
- Geo-referenced maps can be downloaded for offline use
- Relatively big screen compared to a handheld GPS
- Can be used to communicate in an emergency. See Emergency Communications
- Emergency warnings (fire, flood, wind, storm) and weather forecasts can be received
Limitations of a mobile phone
- Using a mobile phone as a GPS, or camera or for anything else reduces battery life. The more functions that are turned on and the more often the screen is used, the shorter the battery life.
- A mobile phone battery will tend to flatten very quickly on bushwalks, if not turned to flight mode, due to a weak or patchy signal (see notes on Mobile phones page).
- The screen is difficult to see in bright conditions and very difficult to use if wet, cold, shivering, sweaty or otherwise impaired.
- Mobile phones are not robust; very easily damaged if dropped or fallen on. A broken screen is unusable. On the other hand, handheld GPS units have very robust construction and are made for use in the outdoors.
Optimising the use of a mobile phone for navigation
When purchasing a phone:
- some mobile phones are water resistant
- some mobile phones have a ‘glove’ setting, enabling touch screen operation with gloved fingers
- some designs are more robust
- protect the phone with heavy duty ‘armoured’ case with a lanyard attachment
When preparing for a trip:
- download any maps required ahead of the trip
- practice practice practice
- pack at least 1 power bank battery and correct cable, to recharge the phone (solar panels are an alternative on extended trips)
- store in a secure waterproof pouch when not in use
- switch to flight mode, and use only when necessary.
Finding location on a paper map from a map screen
Generally it’s reasonably easy to identify the current location on a paper topo map or mud map using the location shown on the map of a mobile phone or GPS screen. Nearby named features; tracks, rivers, peaks etc are used as reference points and the exact location found from the contours and the “shape” of features and the countryside.
However, it is possible for the topographic map installed on the device is quite different in detail to the paper topo map; different contour interval, different tracks shown and named, and even different background colours.
If confusion arises:
- ensure both maps are being viewed with north up.
- zoom the digital map out until some named or major features are identifiable. Locate these features on the paper map.
- compare the shape; the twists and turns of main tracks, creeks and rivers until the layout of the countryside can be matched on the screen and on the paper map.
- zoom in on the device slowly to the current location while keeping track of matching features on the paper map, until that location is confirmed on the paper map.