GPS Accuracy

Rich Owings at www.GPStracklog.com has a great post on GPS accuracy.  The bad news: accuracy changes from day to day.  The good news: accuracy will be roughly between 10-50 feet most of the time.

From Owings' post:

"You may not realize it, but GPS accuracy varies from day to day. Satellites occasionally go on the fritz, but the biggest issue is the arrangement of the constellation relative to your position."

To read Owing's post go here.

My post on Orienting a Map has received a lot of hits since first published three years ago.  The fundamentals are still essentials of back country navigation.

A quality topographic map is key to your backcountry travels.
Many quality outdoor stores have good maps.  Do check out www.MyTopo.com  Map Pass and the free site at www.mappingsupport.com/p/gmap4.html

Orienting a map is a starting point to identify where I am, where I want to go and where I have been. I orient my topographic map (topo) before I leave the trail head and at regular intervals during a hike.

To read the rest of this post go here.

Robin is one happy GPS user. He has owned his Garmin GPS 60 for two years. The Waypoint file is full of entries. He had recorded hunting trips, camping expeditions with the kids, a few geocaches, and of course the favorite fishing spot. His GPS receiver will hold 500 Waypoints and he has over 350 saved. What a collection of data. But is Robin really managing his Waypoints effectively?

Nope.

Lots of things can happen to a Waypoint or data file. You can put data in. You can take data out. You can lose it (the GPS breaks or the wrong button entry is selected.) But be careful, far worse, too much data can make your navigation difficult.

In my land navigation class I stress keeping your navigation simple. Frequent and simple Waypoint management is essential to GPS use. When it’s time to return to the truck, it should be obvious what Waypoint to select.

Dump the junk before the start of a trip. As you leave the trail head your GPS should have only necessary data saved on your GPS. That Waypoint for the fishing hole is important but needs to be saved elsewhere.

Start by deleting Waypoints that really are not needed. Free those data bites to the atmosphere.

To save your “got to have, must save Waypoints:”

1. Use Garmin’s “Trip and Waypoint Manager.” It probably came with your GPS. It can also be purchased from Garmin for about $30.00; www.garmin.com. Down load those Waypoints to your PC.
2. If you don’t have the Garmin program, consider “Easy GPS.” It is free and available at www.easygps.com.
3. Log the important data in a notebook.

To read the rest of the post go here.

Do you have a favorite navigation web site or blog?

Share your information with us. 

Please forward a link to your favorite web site or blog that provides information on land navigation, GPS in general and backcountry survival.

Send it to: mapcompassandgps@gmail.com

Taking Good Care of Your Compass

Check out my latest post on Seattlebackpackersmagazine.com about taking care of your magnetic compass. 

 

If a hiker is willing to spend hundreds of dollars on a pair of boots why not spend a bit more for a decent magnetic compass; it can make a huge difference.

 

The hiker arrived at the trailhead and was getting ready to start out on his journey. He powered up the GPS to mark his location.  He also brought out the magnetic compass to double check his heading and first bearing. Strangely, he knew he was heading in an easterly direction, he was after all, pointing straight down the trail and the trail tracked 090°, due east. But after aligning the magnetic compass, the compass heading was 13° off.  The hiker correctly held up his movement until he could resolve the issue.

 

To read the rest of the post go here.

For more information about measuring a magnetic compass bearing check out this post.

Direction - Bearngs and Azimuths

In land navigation, bearings and azimuths are used to describe the angular measurement to a distant object.  This is an essential component of compass and GPS usage.

In the field, the hiker needs a way to express the direction to an object or the direction of intended travel.  The two terms most commonly used for such expression are bearings and azimuth.  Both are described by units of angular measurement.

Azimuth is the common term used by the military in land navigation.

Bearing is the term most frequently used by those recreating in the backcountry.  Bearing will be used during the rest of this discussion.  Bearing is the horizontal angle measured clockwise from North.

The degree is the common unit of measurement of a bearing.  A degree can be broken down into the following terms:

                        A circle = 360°                     

1 degree (1°) = 60 minutes

                        1 minute = 60 seconds

Thankfully, most direction information is expressed simply in degrees.  For example, the direction to a destination calculated by a Global Positioning System (GPS) receiver will be stated in degrees.

Degrees will always be described in relationship to a circle and a starting point.  A circle is comprised of 360 degrees; check your compass dial to confirm.  In land navigation, the starting point is from north.  Commonly, the angular measurement is calculated from one of three options.   These are True North, Magnetic North and Grid North.

True North is the direction from any point on the globe to the North Pole.  All lines of longitude are lines that run true north and south.  Angular measurement is calculated from the starting value (0°) clockwise to the desired direction.  For example, east has a direction of 90°.  (The best practice is to state the bearing in three digits, thus, 90° becomes 090°.)  Bearings measured from the North Pole are referred to as degrees true.

Magnetic North is the direction to the Magnetic North Pole.  Note that Magnetic North and True North are not the same.  The angular difference between True North and Magnetic North is known as declination.  (For more information read my post Declination). The angular measurement is measured clockwise from the magnetic north arrow to the desired direction.

Grid North for the recreating hiker is in relationship to Universal Transvers Mercator (UTM) grid.  The globe is bounded by 60 UTM zones that stretch north to south.  The central meridian of the UTM zone is aligned to true north.

For the backcountry navigator, the simplest method is to use bearings that are in relation to true north.  In my navigation classes I suggest that students “match the map” that will be used in the field.  In most cases a map is oriented to the North Pole.  A GPS can be setup such that the receiver provides direction information in degrees true.  I also recommend consider the purchase of a declination adjustable compass such as the Suunto M3 or the Silva Ranger.  Though the magnetic needle always point to magnetic north, the dial provides direction data in degrees true.  Thus, both instruments (GPS and Compass) will match the map.

 

Survival Myths

For just about any survival situation, there’s a wealth of knowledge out there, and a lot of it’s bad.  Often things aren’t helped by the burgeoning number of survival reality shows, which are designed to entertain rather than to educate.

by Leon Pantenburg

The proliferation of survival shows had brought about a dangerous mind set. Many people think that because they saw a survival method performed on a TV show, that technique will work for them.

In many cases, if not most, the TV show is scripted to be entertainment. Actual, valid survival skills are secondary to sensationalism. Don’t rely on them for your survival training.
But a worse situation can occur when some of these myths perpetuated by the TV survivalists are accepted as fact. Without trying them, people assume they know a valuable skill or technique.

Dryer lint as firestarter, for example. At just about every firemaking presentation, someone will ask, as if it’s a new idea, why I don’t recommend  carrying lint.

To read the rest of Leon's post go here.

A Star to Guide Us - the North Star

The North Star is a beacon that we can use to guide us in the backcountry.

Few hikers use the celestial bodies in the night sky to navigate by.  But on a clear night, the night sky provides a feature that is an excellent source of direction.  It doesn’t matter if it is June or November, if you are in Wyoming or Oregon.

The North Star or Polaris is the principle star that I will focus on. 

For the backcountry hiker consider that Polaris is fixed in position over the northern pole.  Unique from other celestial stars and planets, Polaris is very closely aligned to the earth’s axis.  Stars and planets rotate around Polaris.  And like the sun, this rotation is from east to west through the sky.  Polaris will be found approximately half way between the northern horizon and straight overhead.  In the northern hemisphere, Polaris can found in our northern sky and is never more 1° from true north – the North Pole. 

 



Outdoor Quest - Finding Polaris
 

 

 

 

 

To read the rest of the post go here.

 



 

Stay Safe With Your Spot Locator - Update

Since writing this post two years ago SPOT has continued to be a very popular backcountry tool for the hiker.  In those two years Global Star has come out with new models.  Further, the rumors of Global Star's demise (spread by the competitors) has been transparent to the user and may be false.


 

 

I have used mine while hunting, camping and hiking.  I have also been on the receiving end as a SAR team member while tracking a lost hiker.  SAR teams in my home state now use SPOT locators to track team members while they are in the field because the device provides near real time updates.

While backpacking with my sons, hundreds of miles from home in a remote area of Glacier National Park, I was able to send information to my wife every evening.  Those messages from my SPOT (which stands for “SPOT”) locator gave my wife peace-of-mind.

Locator beacons have been available to outdoorsmen for several years.  The basic idea is pretty straight forward: to help someone stay out of trouble in the backcountry by providing a method for them get help.

Spot units are communication devices that use satellite systems to link to control stations to forward messages.  SPOT, manufactured by Global Star Communications, has made locator beacons affordable and multifunctional.  Criticized initially for a lack of GPS sensitivity and other issues, SPOT responded with the SPOT II & III, an upgraded and improved, smaller and more reliable model.  An annual subscription fee is charged to use a SPOT unit.

SPOT units are a good choice for anyone who wants to stay connected to family, friends and emergency responders.  One of my friends gives his wife the SPOT when they go shopping in Portland, Or., at the malls!  Talk about urban survival skills!

To read the rest of the post go here.