Using GPS, Maps and Mapping. Tracks4Africa & Top GPS Tips for Planning a Journey
The following tips are based upon the experience of myself and in addition those of Kevin Bolton, probably the most knowledgeable and experienced user of GPS in South Africa. However before reviewing these tips it is important to know a bit about datums and why Tracks4Africa is necessary for travel outside South Africa
The Reason Why Tracks4Africa is essential when moving outside of South Africa (and also recommended even for travel within South Africa)
To understand the importance of what I'm stating you need to realise that different countries use different datums (reference points) for their maps. In simple language this means that co-ordinates transferred from a map using a particular datum onto a GPS with a different datum will not translate into the exact same spot and can be hundreds of metres out (this error can be vital in many cases).
Not only this the fact is that many maps will not even show the datum in use and as such coordinates from the map can bear no resemblance to the real position and as such are completely unreliable.
Even in South Africa the official 1:50,000 maps do not have the same datum. Some have the Cape Datum and the more modern ones the WGS 84 Datum. South Africa is standardizing on the WGS 84 but it takes time to change all the maps.
| Country | Datum |
| South Africa | Cape or WGS 84 (the datum is printed at the bottom of the 1:50,000 maps) |
| Lesotho Botswana Swaziland Zaire Zambia Zimbabwe |
These countries all use Arc 1950 |
| Namibia | Schwareck |
| Kenya Tanzania |
Arc 1960 |
| New South Africa | WGS 84... this is also becoming the international standard |
So What Does This Mean for Track4Africa?
The maps produced by Track4Africa are created based upon ACTUAL journeys made and standardised to the WGS 84 datum. This means the GPS can be set to the WGS 84 datum and the co-ordinates on the Tracks4Africa map will correspond exactly with the GPS coordinates no matter which country is visited.
Because Tracks4Africa is based upon actual verified journeys all points of interest data is also reliable eg petrol availability.
Good GPS Tips
- Always use your common sense in addition to a GPS
- Do not leave South Africa without Tracks4Africa
- Do not leave without a good paper map
- Do not leave without a compass.
- In an ideal scenario you would have a back up GPS or travel with other people who have a GPS.
- Make sure your GPS can record tracks and can preferably track back. In general street navigation GPS units do not have track back installed.
- Inside South Africa set up the GPS for "Fastest Route" and NOT "Shortest Route"... in this way you can avoid driving through areas completely unfamiliar to you
- Quad helix antenna is better bet than patch antenna in terms of receiving GPS signals in difficult areas. In addition accuracy is greater and lock on to satellites is faster.
- Duracell batteries are not recommended. The best batteries are Energizer Lithium. According to Kevin these batteries give up to 5 times longer life, do not have same tendency to leak and are 33% lighter in weight. Carry extra batteries and keep in a safe place.
- Always make sure when using a GPS in conjunction with a map that the datum is the same on the GPS as used on the map... eg WGS84 or Cape or Arc 160 as the case might be. Each GPS can be set to the correct datum.
- The default datum setting on your GPS should be WGS84
- Enable WAAS on the GPS
- When walking with a GPS hold it away from the body to get best signal... ideal place is in a pocket on a hat.
- Some Landrovers, Peugeot, Citroen and Renault cars may need an external antenna to get good GPS reception while driving.
- Beware on some maps that the co-ordinates used and the datum of the map may be different. Tracks4Africa SHOULD be used to verify published co-ordinate data when planning a complex trip outside South Africa.
- Match the GPS co-ordinate system with the map is use... eg Degrees Minute Decimal Seconds or other format.
- If you ever get lost always transmit position data in system used on your GPS or map.
- 1 second on a map is roughly 30 metres
- 1 degree on a map is roughly 100km
- A compass tip... do not buy a compass outside South Africa in Northern hemisphere for use here. The reason is that the needle tends to be pulled down thereby interfering with free rotation of magnetic needle.
- How to choose a GPS