Basic Navigation Leading Cadet Training Basic Navigation Map

Basic Navigation Leading Cadet Training Basic Navigation Map and Compass Lecture 1

Basic Navigation Basic navigation is – Knowing where you are on the map. Knowing where you want to get to. And finding the best route to get there. Good navigation is a combination of: Good Map Reading Skills. and good Compass Work.

Magnetic North The Earth has its own magnetic field, so a free moving needle aligns itself with this field. This needle will always point in a north/south direction. UNFORTUNATELY the magnetic north pole does not coincide with the geographical north pole (true north).

True, Magnetic & Grid North True North is the direction to the earth's axis Magnetic North is in Hudson Bay, Canada. o In the UK Grid North is about 2 East of True North. The other problem is, Magnetic North changes its position over time ! UK Grid North Magnetic North True North

True or Grid North ? Lines of Longitude get closer as they approach the North and South Poles. Grid Lines differ in that they cover a flat surface (i. e. the Map) Because of this, Grid Lines don’t match lines of Latitude or Longitude, nor do they point to the Magnetic pole, or to the North Pole (True North) Instead they are said to point to an imaginary point called Grid North

True or Grid North ? So when navigating on a map we use Grid North Not Magnetic North and not True North The Symbol of Magnetic North The Symbol of True North The Symbol of Grid North

Magnetic Variation is the angular difference between true north and magnetic north, UK Grid North and is different across the world. In some areas it is east of true Magnetic north. North True North So Magnetic Variation must always be allowed for when using a map and compass for navigating. To help, magnetic variation is always displayed on the bottom right of a Map. Magnetic Variation

Magnetic Variation Because all compass references are made to either Grid North or Magnetic North, UK Grid North the angular difference between True Magnetic North these 2 north's must be known. This angular difference is called the Grid Magnetic Angle (GMA) Grid-Magnetic Angle Magnetic Variation

Summary True North and south are at the geographical poles. Grid North is the direction to which all Ordnance Survey Maps are oriented. We take our map bearings using Grid North. Magnetic North is the direction to which a compass points, and in the UK it is located approximately 1º West of Grid North.

Orientate Your Map When using a map the first thing to do is to Set the Map with your surroundings, using identifiable features. Hill Island River Woods Church

Orientate Your Map Set the Map with your surroundings Stream junction Shoulder on a steep slope You are here Old walled enclosure Re-entrant at base of slope

Orientate Your Map Set the GMA against the direction of travel arrow of your Compass. If you cannot Put the compass on the map set the map and align the North-South using observable features grid lines. you can set it with your compass. Turn map & compass TOGETHER until the needle falls inside the orienting arrow – red end pointing North.

Finding North If you find it difficult to set your map using features on the ground, it may help to know where North is. Without a compass however, determining North is a bit tricky. You can get a rough idea of where North is by using one of the following methods…. .

Finding North 1. The Pole Star In the northern hemisphere the North Pole is indicated by the position of the Pole Star. First find the Great Bear or Plough. Find the two ‘pointer’ stars and follow them for a distance of four times their separation. And there you find the Pole Star

Finding North 2. Using a Watch If you can see the Sun, hold your watch with the hour hand pointing at the sun. Half the angle between the 12 o’clock position and the hour hand points South. If you have a Digital watch, draw a diagram showing the correct time, and use that instead. Due South.

Finding North 3. The Shadow Method Place a stick in the ground and mark the end of its shadow. Wait for 10 to 15 minutes, and then mark the new shadow. A line between the marks runs roughly west to east. The line dissecting this shows north to south East South North West

Check of Understanding The difference between true north and grid north arises because. . . Latitude and longitude lines do not match grid lines Grid lines get closer together near the Earths poles Latitude and longitude lines match grid lines exactly Lines of latitude are not parallel

Check of Understanding The position of the magnetic north pole: Is not fixed but changes a little every year Is the same as the true north pole Is fixed and remains in the same place constantly Only changes when new maps are issued

Check of Understanding The angular difference between magnetic north and grid north on a map is known as? Compass deviation angle Grid magnetic angle Magnetic deviation angle Grid deviation angle

Check of Understanding Which of these symbols represents magnetic north? W X Y Z

Check of Understanding What is the approximate difference between true north and grid north? 0 to 5 degrees 6 to 8 degrees 8 to 10 degrees More than 10 degrees

Check of Understanding Which of these statements about the direction of magnetic north is true? It is the same as true north It is the same as both true north and grid north It differs from both grid north and true north It is the same as grid north

Check of Understanding Where on a M 726 OS map is the Technical Information giving details of magnetic variation located: The bottom right side At the very top On the extreme left On the back

Check of Understanding Which north do you use when navigation with an Ordnance Survey map? Grid North True North Geographic North Magnetic North

Check of Understanding When using a map what is the first thing you do? Organise the Map Sight the Map Range the Map Set the Map

Check of Understanding Which of the following is not a method for determining north without a compass? Finding the wind direction Finding the Pole Star Using a watch and the sun Using shadows and a stick

Check of Understanding From the diagram, if a shadow moves from position 1 to position 2 which arrow points to the north? W X Y Z

Check of Understanding How can you find north by day without a compass? Use a map and stick stuck vertically in the ground Use your mobile phone Ask the rest of the group and make a considered decision By pointing the hour hand of your watch at the sun, bisect the angle between that and the 12 o'clock

Check of Understanding From the diagram, which letter indicates the correct position of the Pole Star? W X Y Z

Basic Navigation Leading Cadet Training End of Presentation