How to Find the North Star Using the Big Dipper

How to Find the North Star Using the Big Dipper

To find the North Star, the quickest and easiest way is to first locate the Big Dipper (see main image).

This is also known as Ursa Major (forms part of Ursa Major), The Plough or Great Bear.

Once found, follow the “handle” of the Big Dipper along to the “bowl” section, which consists of four stars.

Locate the two outermost stars of the bowl (lower right and upper right) and extend an imaginary line between the two stars, upwards, for approximately 5 times the distance between them.

You will come to another star.

This is the North Star.

Is the North Star the brightest?

No, contrary to common belief, the North Star is not the brightest star in the night sky, it is actually not that bright at all.

The brightest star in the night sky is Sirius, which is also known as the ‘Dog Star’.

Is the North Star in the Little Dipper?

Yes, the North Star is in the Little Dipper, which forms part of the constellation Ursa Minor.

The North Star’s correct name is Polaris.

To the naked eye, Polaris is not as bright as you would imagine the North Star to be. It glows at a similar level to its surrounding stars, albeit a little brighter than most.

Polaris actually forms part of the constellation called Ursa Minor, also known as Little Bear or Little Dipper.

How is the North Star used for navigation?

The North Star has been used by man for navigation for thousands of years.

As mentioned above, it holds a constant position in the sky and for this fact can be relied upon for accurate navigation.

At this point in time, if you transfer its position in the sky, straight down to a point on the Earth’s horizon, you will have found Earth’s True North.

Once you have pinpointed this, you have a reference on Earth to base your navigation on.

This is the easiest way to find North via the stars.

As you will see from the diagram, it forms the tip of the handle of the Little Dipper and is the brightest of this constellation.

You will notice if you observe the North Star for an extended period of time, that it appears to remain in the same place, while all other stars rotate around it.

This is, of course, the Earth rotating, but it is worth knowing.

The direction of travel of the Big Dipper and other stars around Polaris is clockwise.

The video below from AlfieAesthetics gives a good video explanation:

Is the Big Dipper a bear?

Not exactly…The Big Dipper forms part of the constellation known as Ursa Major.

Ursa Major itself is known as The Great Bear.

So the Big Dipper forms part of the Great Bear, but not all of it.

Why is it called Big Dipper?

The Big Dipper gets its name from the fact that it looks like a large ladle, which has a long handle and a large bowl.

The Big Dipper is the common name in North America.

Elsewhere it is known as the Plough (UK), the Northern Dipper (China), the Ladle (Malaysia) as well as other cultures knowing it as a salmon net or butcher’s cleaver. 

Which star is the North Star in the Big Dipper?

As mentioned above, the North Star is not in the Big Dipper, it is actually in the Little Dipper, which forms part of the constellation Ursa Minor. 

You do/can use the Big Dipper to find the North Star on the Little Dipper though.

If you find the Big Dipper, then you should be able to find the Little Dipper.

How far away are the stars in the Big Dipper?

The closest star to Earth in the Big Dipper is Megrez, which is 58 light years away. 

Therefore, the light has taken 58 earth years to reach your eye.

Equally, if the star were to stop shining, or implode today, then you wouldn’t see evidence of this until 58 years later.

That’s pretty impressive and not easy to comprehend!

In miles, this equates to approx 470.5 trillion miles. Now that’s a long way!

How do you find the North Star in the Southern Hemisphere?

The short answer is that you can’t find the North Star in the Southern hemisphere.

At the equator, the North Star sits right on the Earths horizon.

Once you go below this, into the Southern hemisphere, the North Star disappears from view.

Therefore, you cannot view the North Star while you are in the Southern Hemisphere.

Summary

I hope you found ‘How to Find the North Star Using the Big Dipper’ useful.

If you want more great info, I invite you to take a look at our navigation section here which discusses many useful subjects.

How to Tie Different Paracord Knots

How to tie different paracord knotsHow to tie different paracord knots

There are a variety of paracord knots that can be used in bushcraft, each used for different situations and purposes.

In this guide, I will attempt to run through the most useful and widely used paracord knots for your bushcraft needs.

What is the easiest paracord knot?

The easiest paracord knot to tie has to be the overhand knot which we detail below.

With that being said, you can easily master many different knot types through practice, so don’t be overwhelmed.

Start with the overhand and then move on to the more advanced ones.

You will soon become a paracord master!

Rope terminology

Good quality paracord is supple and can be tied into a variety of knots very easily. It is therefore ideal for securing items and providing support.

There are various paracord knots that you can use, depending on what you are aiming to achieve.

Before we begin though, there are a few terms that we need to understand.

  • Working end: this is the end that you are tying the knot with.
  • Standing end: this is the opposite end to the working end.
  • Standing part: any part between the two ends.
  • Bight: a section of cord that is formed into a U shape, without crossing over the standing part.
  • Loop: formed by turning the working end back on itself and crossing the standing part.
Paracord length with working end to the right
Paracord length with working end to the right
Paracord bight
Bight in cord

Now we have the terminology sorted let’s move on to a selection of paracord knots that will cover most situations in the field.

Overhand Knot

 Overhand knot paracord
Overhand knot (double)

One of the simplest and probably one that most people already know is the overhand knot.

It can be tied on one piece of rope or cord or used to tie two pieces together in a parallel fashion.

One use for the single overhand knot is to tie a stopper knot, to keep something in place on the cord.

Another is as a distance aid if you want to measure the distance you have travelled during navigation.

A simple overhand knot in a piece of cord every 100m will aid you when you come to total up the distance covered at the end of your walk.

The overhand knot is also very good for joining two pieces of paracord together, should you want to make a lanyard or form a loop of cord, as shown in the image above.

How to tie overhand knot:

  1. Take the section of cord that you want to tie a knot in and form a loop.
  2. Take the end of the cord and pass it through this loop and pull tight.

Simple!

The Reef Knot (Square Knot)

Reef knot square knot - paracord knots bushcraft
Reef knot

The reef knot, sometimes known as the square knot, is also well known.

It is a useful knot for tying two pieces of cord together for simple tasks and also provides a flat surface, which comes in useful if using it in certain situations such as first aid.

There are better and stronger knots available if you are looking to tie two pieces of cord together and put them under strain, which we will cover later.

Indeed, you certainly shouldn’t be using a reef knot for any type of load.

However, for a simple and quick knot for securing items, such as binding down equipment, etc, the reef knot is a valuable one to know.

How to tie a reef knot:

  1. Hold one end in your right hand (working end) and the other in your left hand (standing end), with both ends facing upwards
  2. Take the working end and pass it over the standing end, then tuck underneath and bring back up – both ends should now be on the opposite side to where they started.
  3. Then take the working end (now on left) and pass it over the top of the standing end, tuck underneath and bring back up.
  4. Pull together to form the knot.

Remember the adage: right over left and under – left over right and under.

Following the above will ensure that you tie the reef knot and not the less useful granny knot.

The Prusik Knot

Prusik Knot Paracord
Prusik knot

Designed by Austrian mountaineer Dr. Karl Prusik, the prusik knots original purpose was to allow a climber to ascend a rope in an emergency (or unplanned) situation.

More on this here.

However, aside from climbing, the prusik knot is also very handy for bushcraft and outdoor purposes.

One of the most common bushcraft/survival uses is for stringing out and tensioning a tarp whilst using a ridgeline.

How to tie a prusik knot:

  1. Create a loop, known as a prusik loop, by tying two of the paracord ends together. You can use a double fisherman’s knot for this or similar.
  2. Next, take the opposite end to the knots and form a bite.
  3. Assuming your chosen pole/branch/rope (that you want to tie onto) is laying horizontally, take your bite end and place over the top of this and then back underneath, so that your bite end and knot and are on the same side and pointing towards you.
  4. Take the knot end and place through the bite end.
  5. Dress towards the pole/branch/rope.
  6. Take the loop that is on top (that was the bite) and take it back over and around again, mimicking the first step.
  7. Again, take the knotted end and place through the loop.
  8. Dress this down to create the prusik knot. You should be able to count four wraps in total.

How it works:

When loaded, the knot tightens securely around its subject. It does this as it is a friction knot.

This allows the user to tighten and secure against this knot, allowing them a fixed point to secure to.

When the knot is unloaded and the tension released, the prusik should loosen, allowing the knot to slide along the rope and re-grip at the next intended point.

This allows the user to move the knot along the rope, to the next required point and then load again.

This allows for a very useful knot, that can be secured and quickly moved as required.

The Clove Hitch

Clove Hitch Knot Paracord Bushcraft Hub
Clove hitch

The clove hitch is used to tie onto a pole or branch and is a handy knot to start a lashing or binding with.

It’s not the best of knots if used on its own, as it slips quite easily and needs to be combined with another knot or lashing to be properly secure – but it is a handy knot to know nonetheless.

How to tie:

  1. Take the end of your cord and place over the top of the pole of or branch that you want to secure to.
  2. Take underneath and back around, so that the working end crosses over the first wrap of cord.
  3. Go around once more and feed the end underneath the ‘cross over’ loop that you just formed, so that the cord runs parallel with the tail end.
  4. Dress together and you will have a clove hitch. This can be confirmed by checking that you have a cross formation, as shown in the above image.

The Bowline Knot

Bowline knot - 550 commercial spec
Bowline knot

If you want to tie a fixed loop at the end of your paracord, the bowline knot is a solid choice.

This knot is great as it locks the loop in place and stops it slipping.

How to tie a bowline knot:

  1. Take the working end of your cord and form a loop in it, where you want the knot to form – the loop should follow an anti-clockwise direction, with the working end should sit on top, and should now be facing downwards, towards you.
  2. Take the working end and thread back through this loop, on the right-hand side, passing it behind the standing end and bringing it back around through the loop again.
  3. Pull tight to form your fixed loop.

You now have a bowline.

The Alpine Butterfly

Alpine butterfly Knot 550 cord green
Alpine butterfly knot

If you want to create a loop in a length of paracord, without having to get the ends involved, then the alpine butterfly knot is a good choice.

It enables you to tie a strong loop that you can tie onto, whilst maintaining the strength of the main line.

This provides a variety of possible uses, one example would be to provide the loops for a trotline, to tie your mono-filament hook-lengths onto.

All in all, a very handy knot to know.

How to tie the alpine butterfly:

  1. Take some slack and wrap the cord around the palm of your hand 3 times.
  2. Take the middle section and tuck it underneath the right-hand section.
  3. Bring it around the front, to the left, and over the original left-hand section.
  4. Take it underneath the other two sections, and bring out on the right-hand side.
  5. Grip the loop on the right and pull the two rope ends to form the fixed loop.

You now have the alpine butterfly.

And now the video run-through of the above…

I hope you find the above article useful for learning and tying your paracord knots. Please let us know how you get on in the comments below.

Thanks for reading

James

Bushcraft Hub

Navigation with a Map and Compass – The Fundamentals

Navigation with a Map and Compass

Being familiar with a map and compass is fundamental to good navigation.

From a safety perspective, you should not be in the outdoors without having at least the basics covered.

GPS units are fast becoming the favoured option for navigation these days, whether it be in a vehicle, on our mobile phone, or a standalone unit.

However, it’s far too easy to solely rely on them.

GPS is a fantastic thing – and when it works, it’s an easy way to navigate, doing all the hard work for you.

It’s always easier being told where to go!

However, you are relying on a lot of things to get that position or next bearing.

Will the batteries last? Can you pick up enough satellites? Are there trees blocking the sky?

It’s not always a straightforward and guaranteed process.

Added to that, electronics can fail – that’s a fact. And if that’s your only navigational tool, what now?

Objective of this article

The aim of this post is to take a complete novice through the basic elements of map and compass, and clearly explain how they are used in the real world, whether it be for bushcraft, survival or adventure purposes.

This will also be handy for the more experienced among you who may need a refresher – which let’s face it, we all do from time to time!

The low-tech option

A map and compass are low-tech – time tested navigational tools.

They don’t require electronics, batteries or satellites to work and therefore, have very little to go wrong.

If you’re going off the beaten track, make sure you learn some basic map and compass skills at a minimum and be sure to carry them both with you – even if it’s just as a backup.

There’s nothing wrong with using GPS if you want to – just don’t solely rely on it.


Maps

There is a lot of information on a map, which can seem a little overwhelming when you first pick one up.

In this section, we will run through the fundamentals and get you up to speed.

Map symbols and what they mean

The symbols, diagrams and all other information that are on your map, correspond to an actual feature or landmark on the ground.

These markings – and what they mean, can be found in the area known as the map key or legend.

It is worth familiarising yourself with these symbols as it will make your map reading more efficient.

You do not need to know them all, as you have the legend on the map close by – and some are self-explanatory – but the more you know, the easier your life will be, as you will not have to constantly cross-reference.

To assist you further, the Ordnance Survey has put together a set of educational flashcards. You can use these to help memorise the symbols and meanings.

Ordnance Survey flash cards
Ordnance Survey flashcards

See the full list here

How to fold a map correctly

Your map will usually arrive pre-folded, so this part is done for you. The problem arises when you need to get it back that way!

To refold it to its original state, follow the steps below:

  • 1 – With the map laid out flat in front of you, fold the bottom half underneath the top half.
  • 2 – Concertina back in on itself, following the direction of the preformed creases.
  • 3 – Fold in half again – Done!

Map scales

What does map scale mean?

The scale of a map depicts its direct relationship between a distance measured on the map and the distance that this measurement relates to on the actual ground.

For example on a 1:50,000 map, this means that for every measurement you take on a map, everything is 50,000 times bigger in the real world, hence the scale of 1:50,000.

OS maps are generally produced in one of two different scales – 1:25,000 & 1:50,000.

What does 1 2500 mean on a map?

It means that 1cm on the map, equals 25,000cm in the real world. This is known as 1:25,000 scale.

Using the 1:25,000 scale as an example, a 1cm measurement on the map = 25,000 times that distance on the actual ground.

So if you convert the real-world figure to meters – a 1cm on the map would become 250 metres in the real world (1cm: 25,000cm).

4cm on the map would become 1km (100,000cm) in the real world – and so on.

How big is a grid square on a 1 25000 map?

At 25,000 scale, a map’s grid square is 4cm x 4cm and equals a 1km x 1km square on the actual ground.

What does a 1 50000 map mean?

It means that 1cm on the map, equals 50,000cm in the real world. This is known as 1:50,000 scale.

Using the 1:50,000 scale, 1cm = 50,000cm in the field, is equal to 500 metres.

This equates to 2cm = 1km.

How big is a grid square on a 1 50000 map?

So a grid square on the 1:50,000 scale, is 2cm x 2cm in size, as opposed to the 4cm x 4cm for the 1:25,000 scale.

So, although the size on the map is different, the grid squares represent a 1km x 1km square on the actual ground for both scales. Hopefully, that’s not confusing.

As you can see, the 1:50k map’s 1km grids are smaller (2cm). This means that the map can cover larger areas, which at times has its advantages.

On the other hand, the 1:25k map’s grids are larger, with the total map covering an overall smaller area, but because the grids are larger, the map is ‘zoomed in’ and therefore shows more detail.

The video below is a Royal Marines training aid and helps explain this visually.

Royal Marines – how to read a map video

Which os map is best for walking

In simple terms, if you want more detail, go for 1:25k scale.

If you want less detail and more ground distance covered on the map – go for 1:50k.

The way I remember this quickly is ‘Less is more’, i.e., the lower number (1:25k) gives more detail than 1: 50k.

Your selection should be based on the situation and preference.

Conversely, in some situations, a 1:25k can actually show too much detail and in doing so, cause the location’s features to become over detailed and less clear.

A 1:50k version of exactly the same section, showing the same feature, although less detailed, can actually be clearer to read – as it is less convoluted.

If you are covering larger areas, such as in a vehicle, then the 1:50k version is probably more appropriate and also means you can take fewer maps with you.

Personally, I like the 1:25k version for outdoor navigation on foot here in the UK.

One of the most popular here in the UK is the Ordnance Survey Explorer range of maps. These come in either the standard version or the Active version, which features a waterproof coating – allowing it to be used in all weathers.

I tend to opt for the standard version and keep it in a map case if the weather is bad.

Navigation with a Map and Compass -  OS Map image
1:25,000 scale Ordnance Survey Explorer map – Cairn Gorm

How to set a map

Setting a map simply means aligning the map’s North, with actual North in the real world.

Do this visually by aligning landmarks on the map, with landmarks on the ground. Your location must be known to do this though.

You can also do this by using your compass. More on this in the compass section later.

Grid references

How to find a grid square

In order to identify a location on a map, you need to accurately pinpoint its location.

This is done in the form of a grid reference. 

On a larger scale, for mapping purposes, the UK is broken up into 100 x 100km squares, or grids.

This is known as the National Grid.

These grids are assigned a pair of letters to identify them as per the diagram below.

Note: The USA, Canada, and many other countries have a very similar system. For this article, we will use the UK system – but the same principles apply – just adapt to your area.

How to find a grid square - National Grid Lines Map
Source: Ordnance Survey

When you purchase a map, you will no doubt have noticed that the map has two letters stamped on it in certain places.

These two letters correspond to one of the areas in the image above that your map is covering.

Your map will likely cover a few different sections of these squares and will, therefore, mention multiple letters in places.

What comes first in a grid reference?

Whichever of these sections you are working off on your map forms the first part of your grid reference. e.g. NH

This way, if you are trying to communicate this grid reference to someone else, they will know which section of the country you are referring to when you state the two letters.

Now that we have established the 100 x 100 km mapping area you are working from, we now need to narrow this down considerably, in order to pinpoint the specific location.

How grid squares are broken down

Now, this 100 x 100km NH section mentioned above, is broken down further into 10 x 10 km squares as below.

How grid squares are broken down
OS National Grid square NH, divided into 10 x 10km squares

You will see these on your map, as the thicker blue lines that intersect at every 10th digit on the map, ie 10, 20, 30…

This has now given us a 10 x 10km (100 square km) area to work in, as shown by the yellow box above.

This is progress, but we still need to get this area down further to achieve any sort of accuracy.

Next, each of the 10x10km squares are broken down further into 1km x 1km grid squares.

How to Find a Grid Square on a Map
A smaller 1 x 1km section of the much larger NH area – this is an actual grid square on a map

Grid squares

How to find grid square

We are now down to the actual grid squares that you see on the map.

These are 1km x 1km wide and of course, give us a total area per grid square one square kilometer.

The red square in the image above signifies one of these squares.

We can now get a reasonable amount of accuracy by simply making reference to this square.

It is still a fairly big area but gives a good high-level indication of where something is located on the map.

We state this by giving a 4 figure grid reference.

How to take a 4 figure grid reference

what are eastings and northings on a map?

What are eastings and northings on a map?

Eastings are the numbers that run along the bottom of a map, from left to right.

Northings are the numbers that run up the side of the map, from bottom to top.

How to read eastings and northings

Eastings

Always start by referencing the numbers that run along the bottom first.

These are known as Eastings, as their numbers increase as they travel East.

To help with the correct sequence, remember the adage:

“Go along the corridor, then up the stairs”

So along the corridor = Eastings.

For the red square above, this would give us a number of 97.

Notice how we reference the number at the start of the square (97), not at the end.

Northings

Now we go “up the stairs” by stating the Northing figure.

This equals 18.

We now need to put these two together to obtain a 4 figure grid reference.

This gives us 97, 18.

We are not finished yet though!

As mentioned earlier, there will be multiple 97, 18 grid squares across the country, so we need to signify which mapping area we are referring to.

We do this by adding the area code at the start of the grid reference.

In this example, we are working off map section NH, which gives us a complete 4 figure grid reference of NH 97,18.

By communicating the above, everyone will know exactly what 1km x 1km section of the country you are referring to.

This is how you give a 4 figure grid reference.

How to take a 6 figure grid reference

Knowing where we are within a 1km square is helpful, but for a more precise measurement, we really want to drill down further and get that location within 100 metres of the actual location on the ground.

To do this we take a 6 figure grid reference.

This is done by breaking that 1km grid square down further, into 10 sections, from left to right and bottom to top.

How to take a 6 figure grid reference

We have our 4 figure grid reference from before of NH 97,18.

This represents the whole of the red square above, but we want to pinpoint the Boat House, so we need to go further still.

As you can see, we need to divide the grid square up further into sections of 10.

You will need to do this mentally, as the grid squares do not go any smaller on a map.

Your compass romer will assist you if this helps. Use the correct romer for the scale of the map you are using. In this case 1:25,000.

We can now locate the boathouse by counting along the bottom first – “along the corridor”.

Then…

Count upwards (“climb the stairs”) to reach the correct square.

In this case, it is 3,3

We now need to add this to the grid squares 4 figure grid ref of NH 97,18 to give us NH 973, 183

This is a six-figure grid reference and is the most common format used for navigation purposes.

Why do we use 6 figure grid references?

A six-figure grid reference is usually the most commonly used type of grid reference, as it gives a decent amount of accuracy for a location.

As above, it gives you an area of 1000m squared, which on the ground is a fairly ‘tight’ area to work with.

However, if you want to get more accurate, you need to break things down further…

How to take a 8 figure grid reference

As mentioned above, a six-figure grid reference is usually as far as you need to go for a good indication of location.

However, there may be times when you need to drill down even further still and provide an 8 figure grid reference.

How accurate is a 8 figure grid reference?

An 8 figure grid reference will give you an area accuracy of 100 x 100 metres – which gives us a total 1000m square area of accuracy.

This tightens things up considerably!

To do this, as you have probably guessed, the square from the 6 fig example above, is further divided into ten each way, to give us another figure to add to our grid reference.

You will again need to do this mentally, and it is a bit tricky to exactly pinpoint it sometimes.

Your compass romer may help, although the numbers are meant for 6 fig references, not 8, so you will need to mentally divide this up.

Example of an 8 figure grid reference

For the location of the Boat House above, we look at where its location is in relation to the smaller square that it sits in.

How to take a 8 figure grid reference
Boat House location – 8 figure reference – grid lines and numbers are imaginary

If we divide this up again – this sits at 4 across and 3 up of the square.

We now add this to our six-figure grid reference to give us NH 9734, 1833

This is how you obtain an eight-figure grid reference.

It’s just a question of drilling down further.

Grid reference quiz

Using the above principles, work out the following (answers at the end):

Grid reference quiz - waterfall

Question 1

What is the 4 figure grid reference for the waterfall above, highlighted in blue?

Grid reference quiz - Blue grid
Waterfall location within grid square NN 91,97 – mentally divided into 10 each way

Question 2

Now, turn this into a 6 figure grid reference by dividing up the above blue grid square mentally.

We know the waterfall sits inside grid square NN 91,97.

We now need to determine where it sits within this grid square.

What two coordinates do we need to add to make this the correct six-figure ref?

Next example

6 figure Grid Reference Quiz - Church
Church location within grid square HL 15,76

Question 3

The above grid square is an entirely fictional HL 15,76 (there shouldn’t be any churches in this region)

Turn this into a 6-figure grid reference, to give the church’s location.

You now should have a good understanding of how grid references work and how to obtain one.

I would suggest you now practice this with an actual map to hone these skills further.

Answers:

Question 1 = NN 91,97

Question 2 = 3 & 2, which gives us the total 6 figure grid ref of NN 913,972

Question 3 = HL 157, 766


The compass

We now move on to the compass and how it relates to navigating with a map.

What makes a compass work?

So, what makes a compass work? Well, the short answer is that the compass has a freely moving and rotating magnetically charged needle, that points to Magnetic North.

This function can then be used to give you a North direction, as well as the others, such as South, East, West and everything in between.

The compass can be used on its own – as well as being able to working conjunction with a map.

As you will see, when M&C are combined, they become highly effective navigational tools.

Let’s explore further…

What are the parts of a compass?

Let’s start with the parts of a standard baseplate compass and what the purpose of each part is.

Note: I am using a plate compass for this article, chiefly a Silva Expedition 4, which is a time tested and an incredibly functional unit, used by NATO and many other organisations worldwide.

Your compass may vary slightly, but will not differ much.

I am also basing this article on the Northern Hemisphere. If you are in the South, you will need to adjust accordingly.

Compass Baseplate Section

What is the baseplate on a compass?

This baseplate is the main ‘plate’ section, that the compass is based on.

On here you will find:

The direction of travel arrow

This is the arrow that points to the direction of travel. There is also an illuminated line just past this arrow, which shows the arrow’s position at night.

Direction of Travel Arrow - Silva Compass
The direction of travel arrow

Ruler

Used to help measure distance on a map and provide a straight edge to draw and take bearings with.

Compass ruler - Silva Expedition 4 Baseplate
Compass ruler

Romer scales

What is a compass Romer?

These are sets of right-angled lines that will be marked out in different scales. These being 1:25,000, 1:40,000 and 1;50,000.

These are used to help obtain a grid reference depending on the scale of the map you are using – by dividing up the map’s grid square into 10.

This gives you a more accurate way of obtaining a 6 figure grid reference.

See the map (grid reference) section above for more info.

Romer scales on Expedition 4 - Map and compass navigation
Romer scales on Expedition 4

Magnifying lens

What is the magnifying glass on a compass for?

The magnifying lens is used to enlarge sections of the map to help you read it.

It also has the added benefit of being able to help you start a fire if needed.

See more in our article here.

What is the magnifying glass on a compass for?
Silva compass – magnifying lens

Rotating bezel section

How to use a compass bezel – compass bezel function.

This is the part that rotates within the baseplate, known as the compass bezel.

This allows you to adjust the angle of the compass against the baseplate which allows you to take bearings, set a map etc.

On this bezel you will find:

Degree markings

These are marked on the outside edge of the bezel, from 0-360 degrees. There will also be North, East, South and West markings on here.

How many degrees are there in a compass?

There are 360 degrees in a compass bezel.

These will usually be marked out as a line for each degree, with a larger marker for every fifth degree and numbered every ten degrees.

How many degrees are there in a compass? - Compass bezel with degree markings
Compass bezel with degree markings

Index line

What is the index line on a compass?

This is the marker that the numbers on the rotating bezel match up to – which indicates the degrees figure for your bearing.

Orienting arrow & Orienting lines

What is the orienting arrow on a compass used for?

This orienting arrow points to 360 degrees (North) and gives a reference for the compasses magnetic needle to line up with. This comes in handy when taking a bearing.

These are also straight lines on the bottom of the bezel, that are parallel with the orienting arrow, that are used to line up with the grid lines on the map.

These help when taking a bearing from a map, or transferring one onto.

What is the orienting arrow on a compass used for? - Orienting lines and orienting arrow
Orienting lines and arrow

Magnetic needle

What is the magnetic needle used for?

This is the business part of the compass that points towards Magnetic North.

As you can probably guess the red end with ‘N’ on it signifies North.

What is the magnetic needle used for? - Silva compass magnetic needle
Magnetic needle – red end points to magnetic North (crazy ay!)

Declination scale

Used on an adjustable declination compass to offset the difference between grid and magnetic North.

More on magnetic declination below.

Adjustable declination compass - Silva Expedition 4
Declination scale

Luminous parts

The key parts glow in the dark to enable you to operate at night.

As you can see in the image, the key parts are illuminated to allow for operation.

Silva compass glow in the dark
Silva compass glow in the dark

What are the parts of a compass – video recap

This video from OS gives a brief visual run-through of the above sections:

Magnetic declination

Compass declination explained

Before we move on to bearings, we need to discuss magnetic declination.

This is the term given to the difference between Grid North and Magnetic North.

In simple terms:

  • Your compass needle will point towards Magnetic North.
  • Your map’s vertical grid lines point towards Grid North.
  • True North is different again and generally ignored for M&C purposes.

As you can see – they are not the same and are located at different points of the globe.

Magnetic Declination Diagram

What is the difference between magnetic north and true north?

Ok, so let’s get this multiple North business out of the way!

As above, there are variations between Grid North, Magnetic North as well as True North.

To be successful in navigation, you need to understand the difference between the three.

Let’s run through them.

What is Grid North used for?

Grid North is what the vertical lines on a map point to. 

The reason for the difference between Grid North and True North is the fact that the vertical lines placed on a flat map, do not perfectly replicate the physical ones that are present on the round Earth.

There is a variation – even though it’s hard to get your head around how this can be the case.

In practice, this variation is very minimal and for most navigational tasks, it can be ignored.

However, just know that there is a difference between Grid N and True N.

What is Magnetic North used for?

Magnetic North or MN is what a compass needle will point to – which is the Magnetic North Pole

It differs from True North above, as the magnetic pole field sits slightly off centre to True North.

This magnetic pole also shifts ever so slightly over time.

Due to this, when comparing MN against GN on a map, an offset is manually added in to allow for this.

This is known as magnetic declination or magnetic variation.

How much of an offset depends on how far away the two Norths are between each other, at that point in time.

The magnetic pole is constantly moving and varies from year to year.

Therefore, when you need to transfer a bearing between a map and compass – or vice versa, you need to manually add in (or subtract) the difference.

The current offset is usually displayed on your map and is known as the declination diagram. 

On this diagram, there will be a date mentioned and the offset figure in degrees.

It will state the difference between True North, Grid North, and Magnetic North.

It will also tell you what the variation is each year and in what direction the variation is moving.

What is the definition of True North

True North is the point at the very centre of the top part of Earth, otherwise known as the North Pole.

It is the Earth’s top axis point.

This is also what the North Star’s position relates to – when its position is transferred down to the Earth’s horizon.

For map and compass purposes, you do not need to worry about True North too much – just to have an understanding of what it is.

And now for the video explanation of the above:

Using a compass to navigate (How to use a compass to find direction)

So you have your compass, you have your map – let’s get moving!

Orientation of the map

What is map orientation?

Firstly, it is helpful to orientate your map, so that it is facing the same way as the land in front of you, i.e., North on the map is facing North in the field.

You don’t have to do this, but I find it simplifies things, especially when you are learning.

To align your map, you can use features on the ground, to give you a good idea.

See How to set a map above.

A quicker and more accurate method though is to place your compass on the map and line up the orienting lines with the vertical grid lines on the map so that they run parallel with each other.

The orienting arrow should be facing North (upwards) on the map.

Keep these lines together and rotate the map and compass, until the magnetic needle’s North rests inside the orienting arrow.

Your map is now facing Magnetic North.

How to take a bearing using a compass

Map bearing to compass bearing

Assuming you know where you currently are on the map, you will no doubt now want to navigate somewhere else.

To do this, firstly find where you are and where you want to travel to.

So on the map, you will now have your start and finish point for this particular leg of the journey.

There will be a straight line between these two points – the direction of this line will form the bearing.

We now need to transfer the direction of this straight line between the two points on the map – to the direction between your start and finish points on the actual ground.

Transferring the bearing (convert map to compass bearing)

To get this bearing onto your compass…

Start by placing the compass edge next to your start point on the map – this is your current location.

Rotate the compass, with its side edge pivoting on the start point, until the other end of this edge lines up with your intended finish point.

The finish point should be at the same end as the direction of travel arrow at the top of the compass.

This ensures the direction of travel arrow is pointing in the right direction for where you need to go.

With this lined up and held in place, rotate the bezel until the orienting lines marry up with the vertical grid lines (eastings) on the map.

Once you have done this, adjust for declination if necessary.

Remember, when adding magnetic variance from grid (map) to mag (compass), add the variation on to the bearing.

Now, lift your compass from the map – it’s time to line your compass up with the real world!

With the compass in your hand and in front of you, rotate the whole compass until the magnetic needle’s North sits inside the orienting arrow.

When these two line up, the compasses direction of travel arrow will be pointing where you need to go.

Pick a landmark in the distance that is on this line. This is your direction of travel.

This whole process can be repeated to cover long distances and is how you use a map and compass to navigate.

Transfer bearing from compass to map

If you want to transfer a bearing from the ground onto a map, you do the above in reverse.

This is handy if you can see a landmark, but are not exactly sure where you are on the map right now.

To do this – from where you are standing, line up the compass’s direction of travel arrow with the landmark in the distance.

Now rotate the bezel until the magnetic needle is inside the orienting arrow.

You now have your bearing – which now needs to be transferred to the map.

Adjust for declination – ‘mag to grid get rid‘ – so deduct the current degrees variation.

Now find the landmark on the map and place one of the straight edges, at the top section of the compass on this point.

Now, rotate the whole compass – pivoting the edge on the landmark, until the magnetic needle sits inside the orienting arrow.

Your position is now somewhere on the line that extends down the edge of the compass from the landmark.

How far is for another article where we will cover resection.

This process takes extra bearings from other landmarks to help pinpoint your actual position on the map.

For now, though, you have the basic ingredients for taking a bearing, from map or compass and using it to navigate.

This will get you started on the right foot.

Magnetic compass errors

What can distort a compass?

Metal: Your compass is a sensitive magnetic instrument and can be affected by metal close by.

Be aware of this and don’t use a compass near large metallic objects, such as a vehicle or iron gate, as these can skew the readings by sending the needle off course.

Compass type: it might sound obvious, but make sure your compass is suitable for the region that you are operating in.

That being the Northern or Southern Hemisphere.

Most global compasses will operate in the North, South and Equator regions, but check yours is suitable for the area you intend to work in.

Further info and resources

Mountain Navigation by Peter Cliff

If you would like some further reading on the subject, we would highly recommend the above book, Mountain Navigation by Peter Cliff.

It’s a nice straightforward book to read, without any unnecessary information.

Purchase links: UK | USA | CAN


Silva Expedition 4-360 Compass

To purchase the compass mentioned above (Silva Expedition 4-360), you can do so by clicking on the relevant link below.

Purchase links: UK | USA | CAN


Where can I buy an ordnance survey map?


To get the relevant outdoor maps for your country, visit one of the links below.

Purchase links: UK | USA | CAN

Summary

You should now be familiar with the basics of map and compass navigation and how the two work together.

This will help you in the field by giving you the very foundations of navigation – which will help you now, but also in the future, as your knowledge and skills progress.

As ever, thanks for reading and please let us know what you thought in the comments below.

Has this helped you? If so, please share with a friend.