The Right Direction with a Thumb Compass, by A. Johansson - part 1

Posted by admin 13/06/2017 0 Comment(s) Orienteering basics,

Author: Andreas Johansson 
republished from Andreas Johansson's Blog post ( www.eajohansson.net )

Introduction

If you enjoy sports like orienteering, adventure racing, or just hiking in the woods, you’ve probably used a compass. Most of us are familiar with the basic base plate compass, but many, especially in orienteering, have long since switched over to thumb compasses.

A thumb compass functions like a regular compass, but is a bit quicker to use in combination with a map, as you can often hold it in the same hand. Let’s take a closer look at what a thumb compass looks like, how to use one (there are a few methods!), and what some of the more popular choices are.

Function

“Any compass that points North. Seriously. All that I want from a compass is a magnetic northerly. Everything else is terrain association.”

– Doug Crytzer, from Facebook Adventure Racing Discussion Group

The basic function of a thumb compass remains the same – indicating north. Like a base plate compass, the thumb compass houses a needle, often with red and white markings (or similar), indicating basic north and south directions.

Suunto Arrow 6 Compass
Suunto Arrow 6 Compass

But, where the base plate compass excels at taking a bearing while in a stable setting, often while not moving, with features like a built-in magnifying lens and multiple scales for measuring distance, the thumb compass wins for speed.

Silva Expedition Baseplate Compass
Silva Expedition Baseplate Compass

The thumb compass design is superior in having close contact with the map, helping you thumb the map (an important skill in orienteering) as you go, and making sure your map is aligned correctly.

Skill Level & Compass Use

As you grow in map and compass skills, especially in orienteering, many people follow a similar path. As a novice, a compass is almost not needed, and skills like reading the map to follow trails, handrails, and so forth are emphasized over using the compass. In the USA, this would be runners on WHITE and YELLOW courses (for novice – beginner orienteers).

The author, Andreas Johansson, teaching his kids about orienteering.
Andreas teaching his kids (Oskar and Emelie) about orienteering.

As skill and experience increase, an individual will begin using the compass for legs (routes between controls or checkpoints) that are less well defined. For example, on ORANGE courses (advanced beginner) where attack points are obvious but controls (or checkpoints) are often some distance off into the woods, a basic compass bearing and pace count can help find the control.

As skill and experience grow even further (think GREEN, RED, and BLUE courses), the compass use changes, to where map reading is back in focus, and the compass is used primarily for orienting the map to north.

For advanced orienteers and racers, reading terrain, running contours, and other advanced navigational techniques are more prominent than stopping to take a bearing from control to control.

“In most races, I only use my compass to orient the map. Well – I sometimes walk a bearing. I use [an] old Brunton base plate compass. It’s indestructible.”

– Robert Kinsely, from Facebook Adventure Racing Discussion Group

Oftentimes, course design prevents the use of bearings regardless, since legs are designed on GREEN, RED, and BLUE to mandate route choice, and include difficult sections with less obvious details. Sometimes, taking a bearing on these courses is less effective than reading the map closely. And that’s where the thumb compass comes in handy!

Thumb Compass Design & Rationale

Thumb compass design centers on being readily available at all times, and in close contact with the map. Oftentimes, the compass and map are held in the same hand, with the compass strapped around the user’s thumb, while grasping the map in the same hand.

The Silva Race Jet 360 Compass with Map
My Silva Race Jet 360 compass with map at a recent training session in Cuyahoga Valley.

Thumb compasses come in both left- and right-hand versions, so it pays to think a bit about what works for you, what feels natural, and what will work in the woods. A baseplate compass is easy to reposition and move around the map, whereas the thumb compass stays put on your hand.

Taking a traditional bearing, such as by using the Silva 1-2-3 System (see below), can be done with both, but depending on the size of the map, might be more cumbersome using a thumb compass. It also depends on how you fold your map (if at all) during a race.

The thumb compass is designed to naturally align with your hand, and with your thumb, for keeping in contact with the map, and with reality.

One of the techniques in orienteering and adventure racing is to thumb the map as you go. Thumbing the map  – that is, moving the tip of your thumb along with your actual location – makes for faster acquisition of where you are on the map, and hopefully prevents you from overrunning a control or checkpoint, or missing an attack point.

Thumbing a map.
Thumbing a map.

Many thumb compass designs extend beyond your thumb (see the Suunto models, and some Moscow models) whereas others are cut short, and your index point for the compass falls short of the tip of your thumb (see Silva or Kanpas models below, for example).

  

It’s all a matter of choice, and you may have to experience it a bit to find the compass that works for you.

“Moscow Compass: love the needle speed, interchangeable between wrist mount or thumb mount. The thumb plate can have a magnifying glass attached to it.”

– Ian Hoag, from Facebook Adventure Racing Discussion Group

Many thumb compass designs from major manufactures (Silva, Moscow, Suunto, Kanpas) include markings on the plate of the thumb compass, like scales, and indicator arrows or other markings. Some of the designs are completely blank.

A new brand on the market, Str8 compasses, has only one design, with indicator lines to aid in map alignment, but no other markings.

The new Str8 Compass
The new Str8 Compass

Some thumb compasses have a rotating bezel, like a traditional baseplate compass, and some have degrees, colors, letters, or other markings on the bezel. If the compass has a rotating bezel at all, it has lines that match the map technical north lines for easy alignment, and for using a bearing system like the Silva 1-2-3 method.

Using any of these models takes a bit of practice, and it’s worth noting that it pays off greatly to practice with your thumb compass (or any compass you plan to use) before a race or event.

For example, if you’re used to a baseplate compass with a 360 degree rotating bezel and scales for measuring distance, and you switch to a blank thumb compass, it can be a bit like night and day. Until you get used to it, that is!

The Silva 1-2-3 System

The Silva 1-2-3 system is an easy method for taking a bearing with a compass, assuming it has a rotating bezel and index lines.

Simply line up the edge or other feature of your compass with the direction of travel you wish to take, rotate the bezel so that the index lines (often below the north/south needle in the compass housing) line up with the north index lines on the map, then remove the compass from the map, and rotate yourself so that the north arrow lines up with the arrow in the bezel, and head off.

This is sometimes called “red-in-the-shed” method in Boy Scout trainings. Easy, right?

Yes, it can be easy, if you’ve practiced. Using a baseplate compass this way is typically part of any map and compass training, or reading materials on map and compass work. But translating that to a thumb compass can be a bit tricky, primarily if the compass doesn’t have the required bezel. So how does that work?

Thumb Compass Methods

Let’s say you’ve decided on a thumb compass without a rotating bezel, like the Silva Race Jet, or Moscow Model 8 Rainbow. How do you take a bearing using one of those compasses, or keep a direction? Let’s start with the rainbow, or color indicator version.

The Rainbow Method / Silva SPECTRA System

Most of the non-rotating bezel thumb compasses use an alternative method to keep track of where the needle should to be in order to head in the direction you want. Silva and Moscow both use the same method, with Silva using a larger needle and larger indicator, and Moscow using a smaller needle, and hence smaller indicators. KanPas is very similar to Moscow, but with different symbols.

   

In both cases, you start off taking a bearing much like in the Silva 1-2-3 system, lining up the compass with your desired direction of travel. Then, since you can’t rotate the bezel, you have to rotate yourself so that the north needle on your compass and the map line up, and off you go.

Keep in mind with the Moscow model, if you’re heading south, you’ll simply have to use the south needle as indicator, since the color markings don’t go all the way around the bezel.

To keep on track, you simply have to remember where the needle is at the time when both map and north arrows are aligned (see below).

This method can be tricky for legs where you prep ahead of time. I frequently prepare my compass while climbing up a hill towards an attack point, only to use the actual bearing a hundred meters later. The rainbow technique also requires you to be very comfortable with aligning yourself to nature and reality on the fly.

The Blank Method

The Blank method is even more complex, where there are no indicators as to where the needle is when north is aligned, and you simply have to remember its position. This method is sometimes preferred by elite level orienteers who have built up extensive experience with map and compass, and have advanced map reading skills.

On the upside, there is less clutter around your compass housing, and the compass is primarily used for aligning the map with north (true or magnetic, depending on your map) as you navigate from control to control.

  

The are only three brands that offer the blank bezel – Silva, Str8, and Kanpas. Silva typically rates very highly, and produces premium products, but Thierry Gueorgiou, orienteering legend, has recently switched to the Str8 model.

Thierry Gueorgiou, orienteering using a Str8 Compass
Thierry Gueorgiou, orienteering using a Str8 Compass

Recommended Thumb Compasses

There are only a handful of compass manufacturers on the market, but picking the right one can be a difficult choice. You may start with one, and move on to another. Some stay brand loyal, while others are ambivalent.

Continue to part 2 ...

Write a Comment