Although a strong urge to perform math is probably not what drove you to leave civilization, there are times when guess-ti-mating is an important skill:
- Your wilderness permit says your campsite must be at least 100 feet from water.
- You are wondering if that tree branch is really high enough to counter-balance a bear bag 10-12 feet off the ground.
- Your son wants to jump of a cliff into the lake and you want to know how high it is, either for bragging rights or for potential insurance paperwork.
- You have just finished setting up your camp and you want to know how much time you have before the sun sets behind that ridge line.
Whatever your reason, the skills to estimate measurements in the wilderness can come in handy.
Body Part Measurements
Okay, that may not have come out right. I am not referring to what you do in the privacy of your own home. I am however referring to how you can use socially acceptable body parts for quick measurements in the wilderness.
Body part measurement has been used for centuries. It did not take long to figure out that humans come in a variety of sizes, including different than me. To solve the standardization challenge important people, such as kings, were used for “good measure.”
- Inch = tip of King’s finger to first knuckle
- Hand = width of King’s hand, about 4 inches
- Foot = length of King’s foot, heel to big toe
- Yard = tip of King’s nose to thumb, or some say circumference of kings waist (though that would certainly be subject to inflation)
- Common Cubit = distance from King’s elbow to tip of middle finger
Since you probably will not be bringing a king with you to the wilderness, knowing your own standard measures can be helpful. If nothing else you will be more convincing when describing that spectacular rainbow trout:
I am telling you it was four hands wide. The thing was practically a cubic.
For wilderness measuring, knowing the distance of your own stride is probably the most helpful. Certainly your stride will vary depending on the steepness of the grade and the burden of your load, but with a little practice you can acquire a fairly consistent “measuring stride.”
Stretch a tape measure across the ground, then casually walk ten steps. Don’t exaggerate your steps, don’t reach for maximum distance, just keep it very natural. After 10 steps look down, identify the distance, and divide by 10. (If you do really enjoy math, take 13 steps and divide by 13 instead). For me, in 10 steps I travel about 25 feet, or 2.5 feet per step. So a campsite for me should be about 40 steps from the water (40 x 2.5 = 100 feet).
It is a lot easier to pace out a distance on level ground than to say walk up a tree or the side of a cliff. To convert a height to a pace-able ground distance, you can use the “stick tilt” method. Hold a stick at arms length such that the tip of the stick is at the top of what you are measuring and your hand grips the stick at the bottom. By keeping your arm fully extended you keep the visible ratio of the stick and the object being measured consistent.
Once you have the correct ratio, tilt the stick 90 degrees (from vertical to horizontal) so you can pace off the distance on the ground. It works best if you have a helper you can position (a little to the left, no no your other left, that’s it, perfect) otherwise you need to look for visual clues on the ground to pace if off yourself, all the while wondering why you no longer have any friends.
How many Brian’s tall is it?
Another technique is to use an object or person of a known height, positioned the same distance away. For example if Brian is standing at the top of the cliff you can use him as a reference. To improve the accuracy, position yourself a reasonable distance back from the cliff. (Besides, if Brian happens to fall off the cliff you will be able to time how long it takes him to reach the bottom, figuring acceleration at 32 feet per second per second.) Holding a stick at arms length you can measure how many “Brian’s” tall the cliff is. If Brian is 6 feet tall, you multiple the number of Brian’s by 6 to get the height. Five and a half Brian’s equals 33 feet (5.5 X 6 = 33). Personally, I recommend bringing someone along who is 10 feet tall, making the math much easier.
New Meaning to Wrist Watch
A quick estimate of time can be made with your hand stretched at arms length. The earth rotates 360 degrees in a 24 hour period. In other words, every hour is represented by 15 degrees of movement across the sky. Assuming you have relatively normal body proportions, a fist at arms length is equal to about 10 decrees of the sky. (Yes, if you are a big person your fist will be bigger, but your arms will also be longer, so the ration is about the same for most people.)
If your fingers are spread out as wide as possible, they cover about 20 degrees of the sky. Whatever method you are using, test it by measuring from the horizon to straight over your head. If you have worked it out correctly, that should be 90 degrees.
When you are setting up camp or preparing dinner and wondering how long the sun will be up, you can simple measure the distance between the sun and the horizon in degrees.
- 30 degrees means you’ve got about 2 hours
- 15 degrees means you only have 1 hour
- A beautiful sunset means you’re pretty much screwed