GPS uses and limitations
By pre-setting waypoints to correspond with locations identified on the route card, a leader can use the GPS as a tool to navigate from point-to-point throughout the day. Alternatively the GPS could be carried as a confirmation tool when rest points are reached or ‘geographic embarrassment’ sets in. Likewise the GPS can be used to locate a point of interest in difficult terrain.
It is vital for bushwalkers and ski tourers to recognise GPS’s limitations. As mentioned, the GPS is dependent on being able to ‘talk’ to satellites. Unfortunately, the locations in which bushwalkers and ski tourers demand that this conversation take place are at times beyond the capabilities of hand-held units.
Most current GPS models have difficulty penetrating the canopy of overhead vegetation. Some users state that this problem is greater when the canopy is wet. If the GPS is unable to make contact with its required number of satellites, no position will be given. Similarly if the unit is being used in a gorge or in steep country, the walls of the valley in conjunction with the canopy may reduce the ‘window’ of sky available to the unit. Once again the result may be an inability for the GPS to ‘talk’ to enough satellites.
The units are dependent on their own power source to function effectively. As with all battery powered equipment, they will not work with flat batteries. Most batteries have poorer performance in cold conditions.