Naismith's rule

Naismith's 1 h / 3 mi + 1 h / 2000 ft can be replaced by: The basic rule assumes hikers of reasonable fitness, on typical terrain, and under normal conditions.

For planning expeditions a team leader may use Naismith's rule in putting together a route card.

[citation needed] In practice, the results of Naismith's rule are usually considered the minimum time necessary to complete a route.

Assuming an individual can maintain a speed on the flat of 5 km/h, the route will take 6 hours and 34 minutes.

[4][6] As you can see, the Scarf's assumption allows also to calculate the time for each speed, not just one as in case of the original Naismith rule.

Over the years several adjustments have been formulated in an attempt to make the rule more accurate by accounting for further variables such as load carried, roughness of terrain, descents and fitness (or lack of it).

Additional adjustments for uneven or unstable terrain or conditions can be estimated by dropping one or more fitness levels.

He assumes the Naismith's base speed of 5 km/h and makes the following further refinements for going downhill:[13][15][21] Later he says that the fitness of the slowest member of a party should be taken into account and thus a more practical formula for a group is:[13]

Naismith 's rule [ 1 ] [ 2 ]
Pace [ 6 ] in minutes per kilometre or mile vs. slope angle resulting from Naismith's rule [ 7 ] for basal speeds of 5 and 4 km / h. [ n 1 ]
A plot of walking speed versus slope resulting from Naismith's rule [ 7 ] and Langmuir corrections [ 7 ] [ 15 ] for base speeds of 5 km/h and 4 km/h compared to Tobler's hiking function . [ 16 ] [ n 1 ]