Wednesday, January 28, 2009

Navigation - Some Essentials


When folk first start navigating, they use handrail features all the time. Handrails are linear features such as paths, fences or streams. They are excellent navigational aids providing safe routes between points. You simply follow the feature without having to keep looking at the map or compass.

Attack Points

When you are homing in on a small target such as the tent or snow hole you plan to spend the night in you want to maximise your chances of finding it first time. To do this it is good to identify a well defined feature near your target and use this as a starting or attack point to find your objective. By approaching your destination like this, if you do not find it first time you can easily return to your known attack point and start again.

Aiming Off

It is foolish to always aim directly at an objective when walking on a bearing in poor visibility as it is highly likely that errors will creep in and you will end up to one side or the other of the target. In this case you will not know which side you are on so it will be guess work to locate the objective. Aiming off describes the technique of purposefully taking a bearing to one side and is commonly used when the objective is a linear feature such as a a stream, path, wall or ridge.

Estimating Distance

As important as the ability to walk on a bearing is the need to accurately estimate distance travelled. Pacing and timing are techniques that require practice in varied conditions before becoming an integral part of your personal toolbag of skills. If you can make it so that effective estimation of distance travelled becomes second nature then it helps free your concentration to make important mountaineering decisions when visibility is poor. Remember that you will need to be able to estimate distances going up, down and across slopes on grass, rocks or snow...

Avoiding Hazards in Poor Visibility

Where a hazard exists which presents a real danger - such as a cliff, cornice, avalanche prone slope or snow covered water for example - then you need a foolproof method of walking around it without losing your overall sense of direction. Doglegs or boxing are two easy techniques for doing this.

By doing a dogleg you simply go along two sides of a triangle rather than along the single long side. This will mean that you have travelled further, but the method will take you clear of the unseen hazard you identified on the map that was presenting a risk.

Boxing is used when you have to avoid a hazard when walking on a bearing. Instead of following a straight line route you walk around three sides of a box as shown in the illustration. By walking to the side at 90 degrees all you have to do is turn the compass until the needle is aligned with east (or west) without changing the important main bearing. Walk for a distance that is easy to remember (say 100m), continue on the main bearing for the desired distance, then turn west (or east) for 100m to be back on line again.

Identifying your Position in Poor Visibility

The aspect of slope underfoot is often a really useful piece of information which helps you identify where you are. In whiteout conditions any sense of horizon is lost and it may be difficult to be sure whether you are travelling up down or across a slope. Rolling a snowball can help you identify the fall-line which is an imaginary line running straight down the hillside. On the map this line runs at 90 degrees to the contour lines.

Establish the direction of the fall-line and take a compass bearing down it. Adjust this magnetic reading to a grid bearing and align the compass on the map until the edge is at 90 degrees to the contours.

This technique does not give you an exact position, but it does provide an additional piece for the jigsaw by confirming which slope you are on.

Monday, January 26, 2009

Monday Morning Wave

All existence moves in waves - heat waves, sound waves, light waves, waves of nausea, joy, relief; shock waves, radio waves - but there is only one place in the known universe where we can actually be one with these transmitters of energy: when we actually ride waves. That's why we get so high from the experience

- Jim Kempton -

Wednesday, January 21, 2009

Navigation - Grid References

Considering their importance in navigation, grid references are comparatively simple. First of all, what are they? Grid references are a numerical system of identifying a given point on a map. The numbers (when used with the right map) are applicable to only one area on that map.

A four figure grid reference will give a position within a kilometre square. This, though useful, is often too big. So generally navigators go further and use six figure references which brings the area down to a 100 metre square.

How do they work? There are a few rules to remember when using a reference. Get them right and there should be no more problems. The numbers, when referred to, identify a grid line on the map.

So first and foremost find the number along the bottom of the map and identify the grid line - Eastings. Then look for the number up the side - Northings. Run a finger up the vertical line and one along the horizontal line until they meet. That should put you at the intersection of two lines forming a cross. Now, which of the four squares do the numbers relate to ? This is the second rule. When using the numbers along the bottom look to the right of the vertical line. when using the numbers on the side look above the horizontal line, at the intersection.

The same rules apply to the six figure grid references. One additional rule is that the first column on the left is zero and the last column is nine. The bottom row is zero and the top row is nine.

Monday, January 19, 2009

Words of Wisdom

True wisdom comes to each of us when we realize how little we understand about life, ourselves, and the world around us.

- Socrates -

Wednesday, January 14, 2009

Navigation - The National Grid

The National Grid is a system of squares devised to enable the map makers to have a point of reference, although it is imaginary, to create an index system allowing parts of the country to be identified. This is different from using latitude and longitude.

This National Grid System consists of a frame of 100 kilometre squares laid over the Ordnance Survey Maps of Great Britain. Each 100 km square has a two letter code and is numbered 00 to 99 from West to East and from South to North. It is important to realise that a six figure reference will appear every 100 km and it is essential to quote the two letter prefix will refer to a square (see image).

Beyond knowing that the National Grid System exists and how to order maps using it, the average hill walker and navigator will have very little need of any additional information.

Monday, January 12, 2009

Words of Wisdom

Thinkers think and doers do. But until the thinkers do and the doers think, progress will be just another word in the already overburdened vocabulary of the talkers who talk

Wednesday, January 07, 2009

Navigation - The 6 Principles

- Where do you want to go?

- Which way are you going?

- How far is it?

- How long will it take?

- What will we see on the way and when we get there?

- Can you show this is the right place now you are here?

Monday, January 05, 2009

Monday Morning Wave

The ocean . . . cold and wild the surf, rushing in to overwhelm the beach, the wind, stinging my cheeks, enveloping me in total freedom

- Scott Holman -

Friday, January 02, 2009

Happy New Rear (Again).........!

....... here's wishing everyone bucket loads of happiness and barrel loads of fun as we enter 2009 :0)