G = [Df + Ff] * [tW + (k * tC)] / 4

Where in:
G = Grade points for the hike

Df = Day factor
Where a: -
1 day hike = -0.11
2 day hike = 0
3 day hike = 0.11
4 day hike = 0.22
Add an additional 0.11
for every extra day thereafter

Ff = Facility factor
Where a: -
Hutted day walk (from one central hut) = 0.5
Multi hutted set trail = 1.0
Tented (carry your own tent) set trail = 1.3
Wilderness area (own route with tents) = 1.5

tW = Total hike distance in km

k = Constant factor of 0.0133

tC = Total of all ascents in metres

EXPLANATION

An explanation of the factors and constants used may help to explain the logic (right or wrong) of the formula.

The basis of the formula is an average person doing a 2 day hutted trail.
It has been assumed that a basic load for this hike would be 10kg plus 1kg per day for food, therefore a total of 12 kg.

Ff - FACILITY FACTOR

Basic load as before equals 12 kg
It is assumed that no additional equipment or weight is required for a hutted route therefore that is the base factor of 1.0.

If the trail consists of day walks from a central hut there should be no requirement to carry all your kit, only the basics of food and water for the day plus the survival items of warm or wet weather clothing, 1st Aid kit, etc.

Therefore for this type of trail the factor is assessed as:
12kg - 6kg /12kg = 0.5

If the trail is a tented route then quite apart from the additional weight of the tent itself (either total or as a split load) there are additional items of stoves, pots, sleeping mattresses, lamps or torches, fuel etc.

This additional weight has been assumed as 3.5kg and therefore the factor is assessed as:
12kg + 3.5kg /12kg = 1.3

k - CONSTANT

This constant is intended to equate the metres climbed over the hike to an equivalent number of kilometres of fairly flat walking.

It is widely written that for every 1 000' (300m) of ascent then one should allow for one hours extra walking time. Assuming that a comfortable flat walking speed equals 4km per hour this means that a 300m climb is equal to 4km.

Therefore:
1m climb = 4.0km /300m = 0.0133km

SUMMARY

As I hope you now understand, I have tried to reduce the hike, taking into account the additional weight etc, to an equivalent number of kilometres of flat walking. The reason for dividing the total by 4 is two fold, firstly it gives a reasonably sized number for the grade and secondly by dividing by 4 should give a number that, if my theories are correct, is the same as the number of hours walking time.

John Neville
Tel: +27 (0)12 993-3531
E-mail: c/o johnn@airports.co.za