Compass / GPS

Compass



Compasses come in many guises from the small button type one might find in a survival tin to expensive prismatic compasses used by the military and surveying companies where extreme accuracy is required. By far the most common type is the protractor compass where you will find Silva manufactures the most popular models. You can find this type of compass at any good outdoor retailer.

When considering which model to buy you need to buy one with a base plate of at least 10cm long and damped to enable the magnetic needle to settle quickly. Depending on whether you intend to use the compass at night it may be advisable to pay a little extra for one with luminous numbers. Other features that would be an advantage are a lanyard so you can hang the compass around your neck to prevent losing it. The base plate should contain a “Romer” etched onto it to enable accurate reading of grid references and measurements of distances for differing map scales. Other standard features included will be a magnifying glass, direction of travel arrow, and compass housing with rotating bezel showing four points of the compass and 360 degree intervals.

The main difference between civilian and military compasses is the fact that on civilian compasses bearings are given in degrees and on a military compass they will be given in “mils”. The main differentiation being that there are 17 mils to every degree therefore mils will be more accurate. However, at Spartan you can use degrees for map reading purposes if the compass you possess does not contain mils as an option.

As with any scientific instrument care should be taken in looking after your compass. Do not drop it or expose it to excessive heat, keep it away from radiators and glove compartments of vehicles or the capsule may develop a bubble, which will impair its efficiency.

Global Positioning System (GPS)



Until recently GPS was only available in the realm of the military. Nowadays, for as little as £100, it is possible for anybody to tap into the multi billion dollars worth of satellite technology that is constantly circling the earth. The military still have a big advantage over the technology we can buy, their equipment can pinpoint their position anywhere in the world to the nearest few centimetres. Whereas we have to be happy with an accuracy of a few metres, not bad though for a one off payment of between £100 to £350. There are no licence fees or running costs other than the batteries they consume.

Although GPS systems are becoming more and more popular and can now be seen in as standard in cars, they still have their limitations. Firstly, they need to be able to “see the sky” to be able to lock onto the satellites which means indoors or in a thick forest they are not much use. The fact that being accurate to a few metres may be an excellent advantage to have when stuck in a white out on a bleak open moor. A few metres off course when leaving a mountain summit could result in a quicker descent than was planned. They do eat batteries quite quickly so you need to carry spares and, if there is a national security alert, the military can block your signal at the press of a button.

A GPS hand held receiver should be an additional piece of kit to be used in conjunction with a map and compass and should never be relied upon solely as your navigation tool. There can be no better skill to learn than to use a map and compass if you plan on getting out into the great outdoors. At Spartan, due to the vastness of our site and the fact that the majority of it is thick coniferous forest, a map and compass is the first method you should consider in getting about the site. When this skill has been mastered then the possibilities for using a GPS receiver will become apparent.

The considerations in buying a GPS unit should be the size of the receiver; more channels give a better fix on the satellites. 12 Channels will give you the best results. A greater number of map datums allow you to use your GPS in other countries as our OS system is not used outside the UK, so you should consider how many you will need. As previously mentioned they use batteries quite readily so an external power source could be handy for use in the car or at home if storing data before a game. The ability to store waypoints is one of the most important features of a GPS as these act as little sign posts on your route that you tick off as you go through them. 500 waypoints is a good starting point. Another important feature is to be able to store pre-determined routes; most good units will allow at least 20 to be stored. If your GPS receiver can be connected to a computer, digital mapping can allow you to plan a route on your screen and with the click of a mouse download all the route, waypoint, and altitude data directly onto your GPS.

The most common GPS units at present are from Magellan and Garmin, but others are catching up and prices are still coming down. You can get demonstrations of these units including digital mapping at any good Outdoor Equipment retailer.