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The section discusses using a handheld GPS for bush navigation.
*** INSERT 3 IMAGES of GPS: MAGELLAN AND GARMIN
A good quality handheld GPS with maps for bushwalking is a sophisticated device that will cost several hundred dollars.
The two main manufacturers are Garmin and Magellan and they make a wide range of models.
Handheld GPS have a host of features and there are many differences between models. Four major points of difference stand out; screen, maps, batteries and toughness.
- Screen: Some models use a touch screen while others use toggle switches and buttons to operate the map cursor and menu functions. Touch screens are simple and easy to use, but become difficult to use in adverse conditions. Screen size is also a consideration. Big is better, except that the device then uses more battery and is heavier.
- Maps: The basemap supplied with most GPS units is a basic one and not of any use for bushwalking. A good topographic map needs to be installed. Topo maps, typically covering Australia and New Zealand, are usually available bundled and pre-installed at purchase. This is reasonably cost efficient. It may be possible to install third party maps as an alternative.
If planning to use the device overseas, the loading of extra maps is another consideration that needs to be investigated carefully prior to purchase.
- Batteries: What is the battery life, what type are they; rechargeable or disposable, and can either type be used?
- Durability and water resistance: Most handheld GPS units are well designed for rugged outdoor use, and they need to be. Check specifications when comparing models.
Using a handheld GPS
It takes a while to setup and learn to use a GPS. Reading the instructions is a start, but a better option may be to go on a trip with someone who already has a similar model to get started, and then practice, practice, practice.
A brief summary of setting up and using a GPS is provided here.
Setting up the unit
The main settings are:
- Units for distance, speed, elevation etc.
- Position coordinates or map datum. UTM, GDA 94 is best for bushwalking, rather than longitude and latitude. With practice the 13 or 14 figure grid reference is easily converted to a 6 figure grid reference for plotting a location on a paper topo map.
- North up. This setting keeps north up at the top of the screen, which is generally the easiest way to read the map on the small screen of the GPS. Some users may prefer Track up (direction of travel is up the screen, like a vehicle-mounted GPS.)
- Compass: Bearings shown as grid or magnetic. The user will have a preference, as long as the user remembers which it is.
Using the GPS
Map screen: This is most useful with the current location shown in the centre of the screen.
Track log: The GPS will record and save a ‘breadcrumb trail’ of the path taken. The file can be renamed for convenience; e.g. Day 6 AAWT. Aside from recording for posterity, the tracklog is useful if a route needs to be re-traced.
Waypoint: Points of interest can be recorded as a location with a name e.g. Day 6 camp. Waypoints can either be recorded in advance as an aid to navigation or recorded on the spot for later reference.
Compass: The device can be set to ‘goto’ a particular location; a waypoint for example. The compass screen will give the bearing to that location and a distance. This is particularly useful in difficult going, as when a major obstacle is met and bypassed, the compass will adjust the bearing and distance accordingly. The compass does need to be checked and calibrated.
Route: A route is pre-defined path created from a group of location points entered into the GPS unit in advance, in the sequence required.
Back at home
A handheld GPS is most useful when used in conjunction with mapping software on a laptop or PC.
Waypoints, track logs and routes are readily transferred between the device and the computer. These files are much easier to view and manage on the larger screen with a mouse. Waypoints and routes for a trip can readily be planned and recorded in advance.
At least one (Garmin) manufacturer produces a range of GPS models that are also an emergency communications device; a satellite tracker and messenger with an SOS button.
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 on the 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.
Route choice must be the bushwalker’s decision
When using a 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 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.
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 handheld GPS map screen. Tracks may be different, and the destination shown on the device may be incorrect. The small screen of a handheld GPS is a limitation. It is much easier to see the ‘big picture’ and route options on a paper map.
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 a handheld GPS for bush navigation.
It does not give the ‘how to’ technical instructions on the various functions. The range of GPS models make this impossible. The instructions for any particular function or device are readily found on the web.
- Beginners guide to choosing a GPS device
- Garmin handheld GPS
- Garmin Inreach handheld GPS and satellite tracker with SOS button
- Magellan handheld GPS
- OziExplorer mapping software for laptop or PC