In the SLMM you may need to use map grid references for a couple of purposes:

1. The control sheets provided at the start include the 6-figure grid references of the controls on your course and you use these to mark which of the pre-printed control circles on your map you need to visit.
2. If you get into difficulties and need to call for help you will need to communicate your location and a grid reference may be the best way to do this.

Harvey and OS maps both use a grid system to help you pinpoint exact locations. Here’s how to use it:

4-figure grid references

Maps are covered in a series of 1 kilometre by 1 kilometre grid squares, each with a 4-digit reference, for example 2453. The first 2 digits are called the ‘eastings’, the vertical lines numbered along the bottom and top of the map and the last 2 digits are the ‘northings’, the horizontal lines numbered along the left and right sides of the map. So the 4-figure grid reference 2453 indicates the 1×1 kilometre square whose bottom left hand corner is the intersection of the 24 easting and the 53 northing.

6-figure grid references

To provide a more accurate location within a 1×1 kilometre grid square we mentally divide both the eastings and northings into tenths and provide another two digits to represent these. So the point marked below in the 2453 grid square can be given a 6-figure grid reference of 243531.

Note that the 6-figure grid reference is actually the bottom left hand corner of an imaginary 100mx100m square containing the feature of interest. So although the 6-figure reference is accurate enough for mountain marathon navigation purposes, it is actually only accurate to within 100m in each direction.

Note that many compasses provide a ‘roamer scale’ that can help you to estimate the tenths needed for a 6-figure reference. There may be several roamer scales for different map scales and you must use the correct one! The SLMM maps are 1:25000.

We’ve produced a couple of guidance notes for teams new to mountain marathons.

The first of these provides some practice in choosing routes between controls. Sometimes these are obvious but sometimes there are several alternatives that can be considered. The document allows you to use previous SLMM courses as examples and view the actual routes taken by winning teams.

The second document provides advice on nutrition during the event, including food and drink during the day and for camp meals. It may help you to keep your calorie to weight ratio high but still have enjoyable food and snacks.