To determine the distance on the ground by ear, it is necessary to stand in such a way that the wind does not directly hit the ears. Eliminate around yourself (several meters) any causes of noise: high dry grass, branches of a bush, etc. It is very important to force yourself to recognize sounds and clearly determine the direction to their source: animals, birds, natural noises, the noise of cars, trains, bells, etc. In this case, it is necessary to take into account the direction of the wind, as well as the echo – repetition of sound as a result of reflection.
Determination of distances in the field by ear.
A monosyllabic echo is heard at a distance of approximately 33 meters from the obstacle. A two-fold echo – at least 66 meters from the obstacle. The passage of sounds is greatly influenced by the terrain and nature of the area. Good audibility will be over an open water surface, in the steppe, in calm weather in the absence of wind and bright sun, with fog and darkness.
At night, a person’s hearing is exacerbated. In winter, in clear frosty weather, the creaking of snow when walking or riding can be heard for several kilometers. Audibility worsens against the wind, in hot sunny weather, on sandy soil, in a forest, in a bush, in dense grass, along arable land and loose fresh snow.
Average daytime audibility on level ground with complete silence.
Train noise – 10 km.
Thunderclap – 5-10 km.
Siren – 7-10 km.
Shot from a hunting rifle – 2-5 km.
Car signal – 2-3 km.
Tractor on a dirt road – 2 km.
Barking of dogs, neighing of horses – 2-3 km.
Truck Noise – 1km.
Inaudible cry of a man – 1 km.
Man steps on the road – 250 – 500 meters.
Cracking falling tree – 600,800 meters.
Knock of an ax, logging – 250 – 500 meters.
Cracked Broken Branch – 80 meters.
Conversation, ringing utensils – 50-100 meters.
Determination of distances on the ground by a light source at night.
Orientation by light, the source of which is known, will help to maintain the desired direction of movement or determine your position on the ground.
Spotlight Vertical Beam – 50 km.
Bonfire – 8 km.
Zarnitsa on the clouds – 5 km.
Flashlight Light – 1.5km.
Determining distances using the construction of geometric shapes on the ground.
This method of constructing geometric figures on the ground is used to determine the width of impassable or impassable sections of the terrain and obstacles, lakes, rivers, ravines, crevices, ravines and the like..
Determining distances using an isosceles triangle.
Choose a flat place on your side of the terrain, approximately equal in width to the measured obstacle. For example, a river. Find and mark your initial location point “A” so that on the opposite side of the river you can see a local object, a separate tree, bush, large stone – point “B”. On its side, at a right angle to the segment “AB”, draw a straight line until (to the point “C”), until the angle “ASV” is formed = 45 degrees. The distance “AC” is the width of the obstacle, since “AB” = “AC”.
Determining distances using a simple triangle.
It is carried out similarly to the previous method, with the difference that the angle “BAC” should be straight, equal to 90 degrees, and the point “C” is chosen so that the angle “ACB” was equal to 60 degrees. Then the width of the obstacle will be equal to twice the value of the distance “AC”. That is, “AB” = 2 X “AC”. To more accurately determine the angles on the ground, you can use various devices, for example, a protractor on the multitool SOG PowerAccess.
Based on the book “Survival beyond the threshold of civilization”.