2/6/05
SURVIVAL NAVIGATION
TERMINAL
LEARNING OBJECTIVE
In a survival situation, and given a survival kit, employ field expedient navigational aids, in accordance with the references. (Chap 7 )
ENABLING LEARNING OBJECTIVES
(1) Without the aid of references, list in writing the considerations for travel, in accordance with the references. (Chap 7 a)
(2) Without the aid of references, describe in writing the seasonal relationship of the sun and its movement during the equinox and solstice, in accordance with the references. (Chap 7 b)
(3) Without the aid of references, and given a circular navigational chart and operating latitude, determine the bearing of the sun at sunrise and sunset, in accordance with the references. (Chap 7 c)
(4) Without the aid of references, construct a pocket navigator, in accordance with the references. (Chap 7 d)
(5) Without the aid of references, describe in writing the methods for locating the North Star, in accordance with the references. (Chap 7 e)
(6) Without the aid of references, navigate with a pocket or a coal burned bowl, in accordance with the references. (Chap 7 f)
OUTLINE
1. CONSIDERATIONS FOR STAYING OR TRAVELING. (Chap 7 a)
a. Stay with the aircraft or vehicle if possible. More than likely somebody knows where it was going. It is also a ready-made shelter.
b. Leave only when:
(1) Certain of present location; have known destination and the ability to get there.
(2) Water, food, shelter, and/or help can be reached.
(3) Convinced that rescue is not coming.
c. If the decision is to travel, the following must also be considered:
(1) Which direction to travel and why.
(2) What plan is to be followed.
(3) What equipment should be taken.
(4) How to mark the trail.
(5) Predicted weather.
d. If the tactical situation permits leave the following information at the departure point:
(1) Departure time.
(2) Destination.
(3) Route of travel/direction.
(4) Personal condition.
(5) Available supplies.
2 . DAYTIME SURVIVAL NAVIGATION
a. Sun Movement. It is generally taken for granted that the sun rises in the east and sets in the west. This rule of thumb, however, is quite misleading. In fact, depending on an observer’s latitude and the season, the sun could rise and set up to 50 degrees off of true east and west.
b. The following diagram and terms are essential to understanding how the sun and stars can help to determine direction:
Position of the Sun at Equinox and Solstice
(1) Summer/Winter Solstice: (21 June/21 December) Two times during the year when the sun has no apparent northward or southward motion.
(2) Vernal/Autumnal Equinox: (20 March/23 September) Two times during the year when the sun crosses the celestial equator and the length of day and night are approximately equal.
c. Sun’s Movement. (Chap 7 b) As reflected in the diagram above, the earth continuously moves in a cycle from solstice to equinox; throughout each day, however, the sun appears to travels in a uniform arc across the sky from sunrise to sunset. Exactly halfway along its daily journey, the sun will be directly south of an observer (or north if the observer is in the Southern Hemisphere). This rule may not apply to observers in the tropics (between 23.5 degrees north and south latitude) or in the polar regions (60 degrees latitude). It is at this point that shadows will appear their shortest. The time at which this occurs is referred to as “local apparent noon.”
d. Local Apparent Noon. Whenever using any type of shadow casting device to determine direction, “local apparent noon” (or the sun’s highest point during the day) must be known. Local apparent noon can be determined by the following methods.
(1) Knowing sunrise and sunset from mission orders, i.e., sunrise 0630 and sunset 1930. Take the total amount of daylight (13 hours), divide by 2 (6 hours 30 minutes), and add to sunrise (0630 plus 6 hours 30 minutes). Based on this example, local apparent noon would be 1300.
(2) Using the string method. The string method is used to find two equidistant marks before and after estimated local apparent noon. The center point between these two marks represents local apparent noon.
e. Sun’s Bearing. (Chap 7 c) With an understanding of the sun’s daily movement, as well as its seasonal paths, a technique is derived that will determine the true bearing of the sun at sunrise and sunset. With the aid of a circular navigational chart, we can accurately navigate based on the sun’s true bearing:
(1) Determine the sun’s maximum amplitude at your operating latitude using the top portion of the chart.
(2) Scale the center baseline of the chart where 0 appears as the middle number; write in the maximum amplitude at the extreme north and south ends of the baseline.
(3) Continue to scale the baseline; you should divide the baseline into 6 to 10 tick marks that represent equal divisions of the maximum amplitude.
(4) From today’s date along the circumference, draw a straight line down until it intersects the baseline.
(5) The number this line intersects is today’s solar amplitude. If the number is left of 0, it is a “north” amplitude; if the number is right of 0, it is a “south” amplitude. Use the formula at the bottom of the chart to determine the sun’s bearing at sunrise or sun set.
Circular Navigational Chart
f. Shadow Stick Construction. This technique will achieve a cardinal direction within 10 degrees of accuracy if done within two hours of local apparent noon. Once again, this technique may be impractical near the polar regions as shadows tend to be very long; similarly, in the tropics shadows are generally very small.
(1) Get a straight, 3-6 foot stick free of branches and pointed at the ends and 3-5 small markers: i.e., sticks, rocks, or nails.
(2) Place the stick upright in the ground and mark the shadow tip with a marker.
(3) Wait 10-15 minutes and mark shadow tip again with a marker.
(4) Repeat this until all of the markers are used.
SHADOW
STICK METHOD
(5) The markers will form a West—East line.
(6) Put your left foot on the first marker and your right foot on the last marker, you will then be facing north.
3. POCKET NAVIGATOR. (Chap 7 d) The only material required is a small piece of paper or other flat-surface material upon which to draw the trace of shadow tips and a 1 to 2 inch pin, nail, twig, wooden matchstick, or other such device to serve as a shadow-casting rod.
a. Set this tiny rod upright on your flat piece of material so that the sun will cause it to cast a shadow. Mark the position where the base of the rod sits so it can be returned to the same spot for later readings. Secure the material so that it will not move and mark the position of the material with string, pebbles, or twigs, so that if you have to move the paper you can put it back exactly as it was. Now, mark the tip of the rod's shadow.
b. As the sun moves, the shadow-tip moves. Make repeated shadow-tip markings every 15 minutes. As you make the marks of the shadow tip, ensure that you write down the times of the points.
c. At the end of the day, connect the shadow-tip markings. The result will normally be a curved line. The closer to the vernal or autumnal equinoxes (March 21 and September 23) the less pronounced the curvature will be. If it is not convenient or the tactical situation does not permit to take a full day's shadow-tip markings, your observation can be continued on subsequent days by orienting the pocket navigator on the ground so that the shadow-tip is aligned with a previously plotted point.
d. The markings made at the sun's highest point during the day, or solar noon, is the north—south line. The direction of north should be indicated with an arrow on the navigator as soon as it is determined. This north-south line is drawn from the base of the rod to the mark made at solar noon. This line is the shortest line that can be drawn from the base of the pin to the shadow-tip curve.
e. To use your pocket navigator, hold it so that with the shadow-tip is aligned with a plotted point at the specified point. i.e.; if it is now 0900 the shadow-tip must be aligned with that point. This will ensure that your pocket navigator is level. The drawn arrow is now oriented to true north, from which you can orient yourself to any desired direction of travel.
f. The pocket navigator will work all day and will not be out of date for approximately one week.
POCKET
NAVIGATOR
4 . NIGHTTIME SURVIVAL NAVIGATION
a. Mark North. To aid you in navigating at night, it is beneficial to watch where the sun goes down. If you're going to start moving after dark mark the northerly direction.
b. Locating the North Star. There are two methods used in locating the North Star. (Chap 7 e)
(1) Using the Big Dipper (Ursa Major). The best indictors are the two "dippers ". The North Star is the last star in the handle of the little dipper, which is not the easiest constellation to find. However, the Big Dipper is one of the most prominent constellations in the Northern Hemisphere. The two lowest stars of the Big Dipper's cup act as pointers to the North Star. If you line up these two stars, they make a straight line that runs directly to the North Star. The distance to the North Star along this line is 5 times that between the two pointer stars.
(2) Using Cassiopeia (Big M or W). Draw a line straight out from the center star, approximately half the distance to the Big Dipper. The North Star will be located there.
LOCATING
THE NORTH STAR
NOTE: Because the Big Dipper and Cassiopeia rotate around the North Star, they will not always appear in the same position in the sky. In the higher latitudes, the North Star is less effective for the purpose of orienting because it appears higher in the sky. At the center of the Arctic circle, it would be directly overhead, and all directions lead South.
c. Southern Cross. In the Southern Hemisphere, Polaris is not visible. There, the Southern Cross is the most distinctive constellation. An imaginary line through the long axis of the Southern Cross, or True Cross, points towards a dark spot devoid of stars approximately three degrees offset from the South Pole. The True Cross should not be confused with the larger cross nearby know as the False Cross, which is less bright, more widely spaced, and has five stars. The True Cross can be confirmed by two closely spaced, very bright stars that trail behind the cross piece. These two stars are often easier to pick out than the cross itself. Look for them. Two of the stars in the True Cross are among the brightest stars in the heavens; they are the stars on the southern and eastern arms. The stars on the northern and western arms are not as conspicuous, but are bright.
Note: The imaginary point depicted in the picture is the dark spot devoid of stars.
SOUTHERN CROSS
d. Moon Navigator. Like the sun, the moon rises in the east and sets in the west. Usethe same method of the shadow stick as you did during the day.
5. IMPROVISED COMPASSES. There are three improvised techniques to construct a compass.
a. Synthetic technique. The required items are a piece of synthetic material, (i.e., parachute cloth), and a small piece of iron or steel that is long, thin, and light. Aluminum or yellow metals won't work (only things that rust will do). A pin or needle is perfect, but a straightened paper clip, piece of steel baling wire, or barbed wire could also work.
(1) Stroke the needle repeatedly in one direction against the synthetic material. Ensure that you lift the material a few inches up into the air at the end of each stroke, returning to the beginning of the needle before descending for another stroke in the same direction. Do this approximately 30 strokes. This will magnetize the needle.
(2) Float the metal on still water using balled up paper, wood chip, or leaf. Gather some water in a non-magnetic container or a scooped out recess in the ground, such as a puddle. Do not use a "tin can" which is made of steel. (An aluminum can would be fine.) Place the float on the water, then the metal on it. It will slowly turn to orient itself.
b. Magnet technique. You will achieve the same results by using a magnet. Follow the same steps as you did with the synthetic material. The magnets you are most likely to have available to you are those in a speaker or headphones of a radio.
c. Magnetization through a battery. A power source of 2 volts or more from a battery can be used with a short length of insulated wire to magnetize metal. Coil the wire around a needle. If the wire is non-insulated, wrap the needle with paper or cardboard. Attach the ends to the battery terminals for 5 minutes.
d. Associated problems with improvised compasses. The following are common problems with all improvised compasses.
(1) Soft steel tends to lose its magnetism fairly quickly, so you will have to demagnetize your needle occasionally, though you should not have to do this more than two or three times a day.
(2) Test your compass by disturbing it after it settles. Do this several times. If it returns to the same alignment, you're OK. It will be lined up north and south, though you will have to determine by other means which end is north. Use the sun, stars, or any other natural signs in the area.
(3) Remember, this will give magnetic north. In extreme northern lattitudes, the declination angle can be extreme.
6. NATURAL NAVIGATION.
a. Find out where the prevailing winds originate.
b. Sun’s path in Northern Hemisphere is SE-SW
1. Bend in trees because of prevailing winds.
2. Sapling Coloration: whiter on one side, darker green on the other. The sunny side (south side) will cause the tree to turn whitish which is a natural sunscreen. White will be on the SW to SE side of the tree. Pick one that is in the open, exposed to the elements all day.
3. Hottest side of a slope will enhance growth: thicker vegetation the SW side.
4. Snow melt on one prominent side of the tree: melt/freeze will indicate the south side.
5. Bleach Rock: the sun’s rays has a bleaching effect, lighter side will be to the south. Obviously white rocks are just white rocks.
c. Look for more than one sign to confirm your direction.
7 . SURVIVAL NAVIGATION TECHNIQUES
a. Navigator.
(1) Employ a navigation method.
(2) Find the cardinal direction.
(3) Pick a steering mark in the desired direction of travel.
b. Maintain a Log. The possibility may arise when you will not have a map of the area. A log will decrease the chance of walking in circles.
(1) Construction.
(a) Use any material available to you i.e., paper, clothing, MRE box, etc.
(b) Draw a field sketch annotating North, prominent terrain features, and friendly/enemy position.
(2) Maintenance.
(a) Annotate distance traveled, elevation gained and lost, and cardinal directions.
(b) Maintain and update field sketch as movement progresses.
(c) Ensure readability of your field sketch. (i.e.; don't clutter the sketch so much that it can't be read.)
c. During Movement Constantly Refer To.
(1) Log.
(2) Steering marks.
d. Actions If You Become Lost.
(1) Immediate action
(a) Orient your sketch. This will probably make your mistake obvious.
(2) Corrective action
(a) Backtrack using steering marks until you have determined the location of your error.
(b) Re-orient your sketch.
(c) Select direction of travel and continue to march.
REFERENCE:
1. FM 21-76, Survival, 1992.
2. AFM 64-5, Survival, 1969.
3. David Seidmond, The Essential Wilderness Navigator, 1995.