Part I

Before being able to take a compass bearing it is essential to understand the relationship between True North, Grid North and Magnetic North. (Part II, walking on a compass bearing, will follow next month).

The Three Norths

Grid North

Grid North is the navigational term for the northward projection of the north-south gridlines on a map. In Ireland it lies to the east of both True and Magnetic North.

True North

True or Geographic North is aligned with the Earth’s axis and points to the geographic North Pole, the axis on which the Earth is spinning. In Ireland it lies west of Grid North and east of Magnetic North.

Magnetic North

Magnetic North is defined as the direction toward which the north-seeking, (red) arrow of a compass points.  Magnetic North is the northern pole of the Earth’s magnetic field and it deviates from True North over time because the earth’s magnetic poles are not fixed in relation to its axis. The current magnetic north pole is located in the Arctic Islands of Canada and is moving very slowly eastwards. In Ireland it currently lies west of both Grid North and True North.

The relative positions of Grid, True and Magnetic North will vary, depending on where you are in the world.

For the purposes of mountain navigation in Ireland and the UK, True North can be ignored.

 

Magnetic Variation

Magnetic variation is the difference in angle (in degrees), between Magnetic North and Grid North. It varies from place to place, and with time.

In those countries that do not use a grid system, magnetic variation is the difference in angle between Magnetic North and True North.

When taking a bearing from the map, we initially align the compass with the north-south grid lines, or Grid North. However, the red end of the compass needle is pointing to Magnetic North, and we must make a small adjustment to the bearing for this.

Information on the magnetic variation for a particular area can be found in the margins of the map. To calculate the Magnetic Variation we need three pieces of information from the map. 1) Year of map update. 2) The rate of decrease (or increase) of magnetic variation. 3) The current year.

From this information it is possible to calculate the adjustment applied to the compass bearing.

At the present time in Ireland the magnetic variation should be added when taking a bearing from the map to follow on the ground.

In The Wicklow mountains the current magnetic variation (2017) is 4.0 °

 

Taking a Bearing

  1. Place the compass on the map so that one of the long lines on the base plate, (or the compass edge, though this is less accurate), is touching both your starting point and target point.  Ensure that the ‘direction of travel arrow’ is pointing towards your target point.     (diagram 1)
  2. Hold the compass firmly on the map and rotate the compass housing until the orienting lines in the base of the housing are lined up with, (running parallel to), the north-south grid lines on the map; and the orienting arrow is pointing north.  (diagram 2)
  3. Take the compass off the map and read the bearing at the index line on the compass housing. This is the Grid Bearing.  (diagram 3)                                                                                                                                                                                                    
  4. Calculate the magnetic variation for your location and add or subtract this from the grid bearing. Adjust the bearing at the index line accordingly. This is the Magnetic Bearing.
  5. Hold the compass in front of you with the direction of travel arrow pointing directly away from you. Turn your whole body until the north end of the needle lines up with the orienting arrow (put red in the shed). The direction of travel arrow is now pointing you towards your target.

Take a compass bearing

 

Take a compass bearing

 

 

 

 

 

 

 

 

 

 

 

Take a compass bearing

To learn more about mountain navigation, or to join one of our very popular Mountain Skills courses, go to:

Mountain Courses

 

 

More and more of us are taking up hiking as a way of getting fitter, enjoying the fresh air, (a moot point perhaps when it’s grey and raining), meeting like-minded people and exploring the natural environment.  For some, heading out into the mountains for the first time can seem daunting, and it can be reassuring to join up with others in a club setting, or go with a more experienced friend or a guide.  Once you have ventured out a few times and listened to conversations about different clothing and equipment, the best routes to take, the secret of good navigation and even what’s in the sandwiches, you realise there is a lot more to this hiking business than you first thought.

Perhaps you feel you don’t want to be just one of the followers in a group any longer, maybe you want to plan and choose your own routes, and to have the confidence and the ability to take to the hills independently.

This is where the Mountain Skills scheme comes in.

Mountain Skills is a comprehensive navigation and personal skills course that will equip you with the basic knowledge and skills to enjoy the mountain environment in safety.  It is administered by Mountaineering Ireland, who appoints individual ‘providers’ to deliver the courses.  It is divided into three parts, Mountain Skills 1 and Mountain Skills 2 are the two training modules, and they each take two days to complete. The third part is the assessment, also over two days. There is no obligation to take all three parts, but you should clearly start with Mountain Skills 1 and progress from there.

Mountain Skills course with Mountaintrails

Navigation is an important aspect of mountain travel, and poor navigation is the single most common cause for calling out a Mountain Rescue team. No surprise then, that navigation features as a large part of the Mountain Skills syllabus. It’s not all about being able to use a compass; reading a map, relating it to the ground, estimating distance and recognising topographical features, these are all important parts of the navigators ‘tool box’.  Mountain Skills teaches you when and how to use each one to move safely and proficiently through the mountains.

The Mountain Skills scheme will also teach you how to recognise and deal with mountain hazards; the environment, weather, hypothermia and terrain hazards are some of the topics covered.  Personal equipment, movement skills and what to do in the event of an emergency are also looked at in detail.

Mountain Skills is not a leadership qualification, but it is a prerequisite if you wanted to move on to higher qualifications such as the Mountain Leader award.

To quote Mountaineering Ireland, “Mountain Skills is a foundation for personal mountaineering proficiency”.

Night navigation on a Mountain Skills course

Many hikers are now taking part in the Mountain Skills scheme, and see it as a great way to acquire the basic skills for safe and enjoyable mountain days, or to fill the gaps in their hillwalking knowledge.

More details of the scheme can be found on the Mountain Skills page of our website, or on the Mountaineering Ireland website.

Mountaintrails has been accredited by Mountaineering Ireland to deliver Mountain Skills courses.

 

What is ‘Wind Chill’?

 
The core temperature of a human body is around 37C. The air around us is usually cooler than this and so we lose body heat, particularly from exposed skin.
Wind chill is the term that describes this heat loss, and the increased effects of low temperatures and wind.
When wind blows across the surface of exposed skin it will remove heat from that surface, making us feel colder than we would in still conditions. Wet skin and wet clothing will exacerbate the problem, as the rate of heat loss increases from wet surfaces.
The body compensates by sending more warm blood to heat the surface layers, eventually reducing our core temperature and risking hypothermia, (see our previous blog on hypothermia).
Well prepared for the icy conditions in the Wicklow mountains.

 

How do we deal with it?

 
We need to reduce the heat loss from our bodies, and the best way to do this is to wear insulating layers of windproof and waterproof clothing.
Waterproof shell jackets are also windproof and the addition of an insulating layer beneath will keep our body warm.
A warm hat is a must, keep it dry by raising the hood on your jacket. Keep your hands warm by wearing gloves, and carry a spare pair to change in to if they get wet.
You can help your body to generate heat by keeping energy levels high, eat regular high calorie snacks and take hot drinks with you on your hike.
It is important to be aware of the potentially dangerous effects of wind chill, and carry appropriate clothing to keep you comfortable, warm and safe when hiking in the winter months.