AY Honors/Map and Compass/Answer Key

This honour is similar to the General Conference's Orienteering Honour. This page will mainly show the answers to the different questions or where a different answer is needed. The Honour is equivalent to the New Zealand NZQA 431 Navigation in Good visibility.

Section 1 – The Map

1a. What is a topographical map?

Refer to Orienteering Honour Basically a view from on top. Symbols and colours to represent true features on the land.

1b. What is found on a topographical map?

Refer to Orienteering Honour Key, contour lines, scale, grid system, trigs, G-MA information, map series and name

1c. Give three uses of a topographical map.

Refer to Orienteering Honour

Decription of land surface showing the shape of the land.

Shows positions of roads, fences, and other man made objects.

Indicates a pictorial view from above

2. What is an orthophoto map?

An orthophoto map uses aerial photos as the background with symbols and other information overlaid. Find a picture of one using Google.

3. Be able to recognize twenty signs and symbols found on a topographical map, giving some in each of the following categories:

Most good tramping (hiking) maps will have a key showing lots of different symbols representing various features.

File:Map key.jpg

map key

4. Know and explain:
a. Elevation.

2. Contour interval

In the NZ old inch to a mile series 1:63360 the difference in height between contours was 100 feet. In the new (2005) metric series 260. the interval is 20 metres.

3. Recognize nine ground formations from their contour lines. Valley, Ridge, Spur, Cliff, Saddle, Shoulder, Escarpment, Knoll, Brow

File:Hollyford map.jpg

Hollyford NZ topo map

4b. Distance

This is a horizontal distance as the crow flies. It is not always a very acurate estimation of the amount of land between two points (land distance). Land distance depends on terrain. Land distance = horizontal distance + (contour interval x number of contour lines).

1. The map scale

Relationship of the horizontal distance between two points on the map and the horizontal distance on the ground in real life. This is shown as a ratio

2. Measuring map distances

Look at the map scale to calculate the real distance

4c. Map grid system.

1. What is the grid system used for?

To accurately locate reference points on a map using a set of 6 numbers.

2. Rules for reading grid references

Grid numbers are a two digit number at the end of each grid line. However a grid reference must contain 6 numbers. 3 from the horizontal and 3 from the vertical. The third digit is the approximate distance in tenths between the two nearest grid lines. Always give the longitude first then latitude.

3. Demonstrate ability to read grid system

A typical grid reference would look like 355884. Most topo maps would explain how to do this on the borders.

5. Know and Explain

a. Grid North

The direction of the North Grid lines run verticaly on the map so the top op the map would be grid north.

b. True North

Usually grid north and true north are the same on topo maps BUT in some cases this is not the case especially as the maps get closer to the artic regions. Check the map do NOT guess or assume or you will be geograhically embarrised ie. lost. Check the magnetic delination on the map.

c. Magnetic North

The direction to which the red pointer needle on the compass nearly always points. The difference between true North and magnetic North is called the magnetic declination or G-MA (Grid Magnetic Angle)

d. Declination

The compass needle alignes itself with the earths magnetic flux (lines)of force passing through the place you are standing. The difference detween true north and magetic north is the G-MA angle. This changes with the earth's magnetic field variations. The G-MA must be considered when using a compass to orientate a map. The map will give a value and time calculation so you can work the value of the angle.

Section Two – The Compass

1. What are the eight major points of the compass and their bearings?

1. N 0°/360°
2. NE 45°
3. E 90°
4. SE 135°
5. S 180°
6. SW 225°
7. W 270°
8. NW 315°

2. Become familiar with several different types of compass.

I have come to understand that there is a difference between Northern Hemisphere compasses and Southern Hemisphere compasses. I am free to be corrected on this point. It may pay to check if you are country hopping.

3. Know the parts of an orienteering compass.

File:Silva compass.jpg

Parts of an Orienteering Compass

4. Demonstrate your ability to:

a. Take a bearing from the map

i. Place long edge of compass along the bearing desired.

ii. Hold compass base on the map and turn compass housing until orienting arrow is parallel to grid lines.

iii. Correct for G-MA

iv. Hold compass at waist and turn until needle aligns with orienting arrow. Travel in the direction of travel arrow.

b. Take a land bearing

Point the travel arrow towards where you want to go. Rotate compass housing until the orienting arrow is directly below the magnetic needle. This will give the magnetic bearing.

c. Take a back bearing

Used to check back where you have come from. The bearing should be 180 deg different or the compass can be turned around so that the white end of needle aligns with the orienting arrow. (Check for slipping)

d. Walk on a magnetic bearing

Set the compass to the required magentic bearing. Follow the travel arrow. It is good practice to look in the direction of travel and find a notable feature in the distance then the compass can go back in your pocket. If visibility poor or nil use a rope and a runner to go ahead and caste about till the runner on the desired bearing. Then move to the stationary runner following the tight rope. If no rope use same method but go by sight, not letting the runner out of your sight you position him in line with the travel arrow.

5. Resection.

a. What is resection?

Used to locate your position on a map

b. Demonstrate your ability to do a resection.

Take two or more back bearings from known features. Remember to transfer backward for G-MA. The point where the two or more bearings cross is your location. Of course is acuracy is not an issue you could look at the features around you and find them on the map and wok out where you are in relation to the sighted features.

Section Three – Direction without the aid of a Compass

1. Watch.

Southern Hemisphere method only.Point the 12 to the sun. Halfway between the hour hand and the 12 is North. You still have to use your intelligence for this as early morning time and evening time care must be taken as to which half you use. Eg 8am sun is rising in the East; point 12 to the sun North is halfway between the 8 and the 12 at the 10. BUT late evening the sun is heading to set in the west say time is 8pm you point the 12 at the sun. North is halfway between the 8 and the 12 at the other side of watch at the 4. This should be used only as a guide as in some countries the real time has been adjusted and sometimes there is daylight saving time etc.

2. Southern Cross.

The Southern Cross is a constellation in the Southern Hemisphere sky. The crux has a longer axis. In your mind extend this about 4 times its lenght. Find the halfway point between the Pointers (Alpha and Beta Centuri) and ake a right angle line to meet the extended line you took from the crux axis. The junction of these two lines is the SCP Southern Celestial Pole. If you were at the South Pole this would be directly above you. This is the point where the night sky revolves around. Point to this spot then lower your arm to the horizon. Where you are pointing is South.

4. Shadow Stick.

This method is a waste of time. We all know the sun rises in the East and sets in the West. The stick shadow shows you this. Also when the sun is at its zenith the highest it gets in the Southern Hemi look at the sun and it is towards the North the opposite in the Northern Hemi. So we learn that at mid day is the best time to find North (or South).

But if you must... place a stick in the ground on an open area. Mark the shaddows at times through out the day. From this you can find North or South (depending what side of the equator you are on) from the shortest shaddow and also East and West by drawing a line from the ends of the longest shaddows assuming you had an early morning and late evening marking with equal time from mid-day. But for this you have to be lucky to have sunshine for most of the day, which usually is not the case if you are lost. Anyhow it is something to know if you do not have a watch to know when mid-day is.

Section Four – Practical

1. Demonstrate how to take a map bearing between two points and then navigate between the two points.

The exercise is not the ability to travel exactly on a bearing between the two points, this is usually imposible in rough wilderness areas. Following an established trail or not so established between the two points would be permissable.

2. Complete a 20 km bushwalk in unfamiliar terrain. The walk is to include one night camping in the open at least 5 km from the mode of transport. Participants are to keep a log book detailing grid references and plans for the proposed route together with records of actual course taken.

Log the pre trip plans of the proposed route.

Log the actual trip giving grid references for the start point, the camp point, the finsih point.

Camping in the open means in tents or forestry hut. on some trails it is not permitted to tent within certain distance to the trail, so check.

Have lots of fun and save lots of memories.