» Survivaltek » Tag » Time

“Thumbdial” – Finding Direction In The Fog

Ken — Sat, 20 Oct 2012 00:00:35 +0000

Without a compass or GPS, how do you determine direction in the fog when you cannot see the sun or landmarks? We know that the sun rises in the East and sets in the West, and if we know the approximate time of day we can tell basic direction. We know that at Noon the sun is due South so mid-morning the sun is South East and in the mid-afternoon the sun is South West. The trick is locating the sun to gain our bearing.

The “thumbdial” method is reminiscent of the “sundial” but works in reverse. A sundial when correctly oriented can determine the time of day. A thumbdial, when you know the time of day tells you the direction of the sun, thus providing orientation. The secret of the thumbdial is that it reveals the sun’s location by revealing it’s shadow.

Begin by standing in an open area and placing the tip of a knife blade on top of your thumbnail and rotate it slowly, watching for a slight shadow to be revealed on the matte textured surface. The location of the sun of course is on the opposite side of the knife blade from the shadow. The wide and narrow silhouette of the blade helps to accent this. The sun’s brightness is defused in fog but still maintains a brighter presence which is revealed by the very slight shadow.

The shadow that you see may be slight, but that does not diminish it’s importance in determining what could be the critical revelation of direction.

Time and Estimation – The Three D’s

Ken — Sat, 04 Jul 2009 20:44:27 +0000

I’ve been pondering some of the ways that we use time in estimation. Here are three applications:
1) Daylight until sunset
2) Distance of Lightning
3) Depth based on sound from a dropped object

Daylight - When you are outdoors and need to know how much daylight you have left to make camp or to return to your car from a hike, stand facing the sun, extend your arm forward while holding your hand horizontally at a 90 degree angle facing you. Hold your hand so that the top of your thumb touches the bottom of the sun. The distance from the top to the bottom of your hand represents an hour. You can use your other hand below to measure another hour and so on. Once the sun sets, there is roughly a half hour of usable light remaining.

Distance - When you see lightning, thunder soon follows, because light travels faster than sound. By counting the seconds between the light and the sound, you can estimate the distance between you and the lightning. Sound travels roughly 1000 feet per second, so 5 seconds equal a mile. When the lightning storm approaches you, the delay grows shorter. When the lightning storm departs, the delay grows longer. Remember, if you can hear thunder, you are close enough to the storm to be struck by lightning, so seek shelter immediately.

Depth - Ever wonder how deep that pit or shaft is? Providing no one is below, you can drop a pebble and count the seconds before you hear it hit the bottom. The actual time is not linear as the object gains speed during it’s decent, however, the following linear time table is a rough guide to depth:

Elapsed Time / Velocity
1 second / -32 feet per second
2 seconds / -64 feet per second
3 seconds / -96 feet per second
4 seconds / -128 feet per second
5 seconds / -160 feet per second
6 seconds / -192 feet per second

Consider thinking “South” for direction

Ken — Wed, 21 May 2008 00:12:47 +0000

I was having coffee outside on a deck today and decided that I wanted to know what direction I was facing. I looked at my wrist watch to notice the time relative to Noon and it gave me a ballpark bearing on South, because the sun is always due South at Noon (actually, Noon – “Standard Time”). You can use a wristwatch in another way by pointing the hour hand at the sun, then determine the mid-point between the hour hand and 12, and THAT is South. It works whether AM or PM during daylight hours. My thoughts in the past have always been oriented to North, as maps are indexed that way, however, thinking “South” allows me to keep the sun in sight during daylight hours, and allows me to determine direction faster. So, consider thinking “South” next time you’re on an outing and the sun is shining.