Navigation for Skiers – Part 1

One of the ski-touring skills that many people find hardest to acquire is map-work. Being able to use a map to work out where you are, where you’ve been and where you think you’re going next is fundamental to safe travel. The best way to manage avalanche risk is by choosing the right terrain. The best way to get information about terrain that you can’t see is from a map. Maps can also aid us to find those hidden powder stashes or secret routes through the trees. Maps can help us to have fun too!

Tori Redmond navigating the Verbier backcountry - Jan 2019

Tori Redmond navigating the Verbier backcountry – Jan 2019

Nowadays, there’s plenty of helpful technology to aid us with our planning and also to find our way when out on the hill. Apps such as FATMAP and White Risk can be very useful, especially in helping us to prioritise information and visualise it on a map. Mapping GPS units are also extremely useful. They often have bigger batteries than a mobile and don’t necessarily rely on touch screens: you can keep your gloves on and your fingers warm. Preloading waypoints can also save you stress and thinking time. However, if you’re downloading other peoples’ waypoints from websites, make sure they’re from a source you know to be accurate.

 

“Anything that can possibly go wrong, does.”

Murphy’s Law as stated by John Sack

 

For the BASI Level 4 European Mountain Safety exam, things go right back to basics. When your GPS batteries are flat and your iPhone is full of snow, the tools you have to rely on are your map, compass, altimeter and pacings.

 

Generally skiers use maps with a scale of 1:50,000 or 1:25,000. This ratio tells you how many times bigger something on the map becomes in the real world. For the first scale, 1mm on the map represents 50,000mm in the real world, which is easier to think of as 50 metres. For the second scale, 1mm on the map represents 25 metres in the real world, so it can potentially show a lot more detail. From this you’d think that we would always want to use 1:25,000 scale maps but 1:50,000 maps can have advantages for skiers.

Which scale map do you need for mountain navigation?

Sometimes there can be too much information on the map, cluttering it up and confusing us. A 1:50,000 map has less information on it and some people prefer to use them for this reason. A 1:25,000 map can also have details on it that we are never going to find under 2 metres of snow. Important things to consider when choosing a waypoint is, “How big is it?” and “Will I to be able to see it when I get there?”. If you’re planning a longer tour, a 1:50,000 map can mean that you only need one map and don’t need to take it out of your map case and refold it in the wind and snow. In Switzerland, special 1:50,000 maps are available for the winter, showing ski-touring routes and slopes over 30°.

 

However, 1:25,000 maps also have their place in winter navigation. In steeper terrain it can be easier see where cols and couloirs are located. It can also be easier to see the changes in slope angle and aspect that will help us with terrain choice and managing the avalanche risk. There can also be extra details, such as buildings or forest roads. A laminated A4 1:25,000 map covers about 6 ½ x 4 ½ km, which can be plenty for a day tour, especially if it’s double sided.

 

For the BASI Level 4 EMS courses, an assessment criterion is for candidates to be able to use either 1:50,000 or 1:25,000 to find their location. However, the kit list only specifies 1:25,000 scale maps and both assessment venues are in France, so it’s best to get some practice using French 1:25,000 maps before your exam.

 

Things can get very mathematical very quickly when it comes to measuring distances from the map and working out timings. Add to this the stress of navigating because the weather is bad or something has gone wrong. Many mountaineers carry a table, like the one shown below, tied to their map case or compass. Print it out at credit card size and laminate it. Remember to leave a wide border of plastic and hole punch through the plastic only to keep the paper waterproof.

An example of a table to work out distances on each scale of map

To sum up, think about the sort of terrain you’re going into and journey you’re planning on doing and choose a map that’s suitable. If you want to be fluent at map-work, make sure that you’re comfortable using both scales. Maps are expensive but they open the door to adventures. We’ve talked about sources of free maps in a previous article. In the next article we’ll start to look at how read the map. We’ll focus on how to interpret contour lines and the different types of information that we can get from them.

 

“You must have a map, no matter how rough. Otherwise you wander all over the place.”

J.R.R. Tolkien interviewed by The Telegraph

 

Written by Dave Roberts – keep an eye out for the next in his 4 part series!

Maps can also help us to find those hidden powder stashes - 4 Vallees, Switzerland - Jan 2019

Maps can also help us to find those hidden powder stashes – 4 Vallees, Switzerland – Jan 2019