Working with Waypoints

This chapter covers the use of waypoints on Garmin receivers. It is copyrighted by Dale DePriest.

Table of Contents


Capturing your position as a Waypoint
Planning Ahead Waypoint Entry
Updating Waypoint Data
Viewing Waypoint Data
Deleting Waypoints
Distance to Waypoints
Proximity Alarms
Tips and Tricks

Waypoints are used to store and remember locations that are of interest to the user. They are often used to store intermediate turns and intersections that help define a route to a particular destination. Similar to the waystations used by pony express riders as stopover points waypoints mark significant places on your journey. In some documents and gps receivers these may also be called landmarks.

Garmin receivers have differing capabilities in the number of waypoints that they can save. The earliest units could save 250 waypoints while later models can store up to 500. The G-12CX can save 1000 waypoints. In addition some units have additional waypoints that are stored in an internal database. These database waypoints are discussed in the chapter on databases.

Generally waypoint names can be anything you wish. On most unit they must be no more than 6 characters long and contain no spaces but can contain any combination of letters and numbers and some punctuation. The newest units permits 10 character names and these can include spaces. The emap, 76 family, and etrex store waypoints in 3 dimensions by including altitude. All other units only store horizontal position. The 76 family will also store depth data for water if an optional depth sensor is attached.

When you first create a new waypoint the unit will automatically assign it a name. These names are three digit numbers starting with 001 and incrementing each time you create a new waypoint. Even if you rename a waypoint the unit will generally assign the next number in the sequence anyway and will not reuse the numbers until it reaches 999. On some units it will automatically use the lowest available number but and on many others you can force the number sequence to continue from wherever you wish. To do this just name a waypoint from the number sequence. For example naming a waypoint to 001 explicitly will cause the next automatic number to be 002 unless this is in use. It will automatically increment until it finds an empty number. Some folks assign a waypoint to a high number to force a block of numbers to be sequential for a particular use.

Capturing your position as a Waypoint

Storing your present location is the usual way to record a waypoint. You simply hit the MARK key, on the G-III, etrex, 76, and emap press and hold the ENTER key, and the waypoint entry form will appear. The location you were at the moment you pressed the button is already saved in the waypoint information on the form so even if you are traveling at 65 miles per hour down the freeway you can reliably capture a single point with the press of the button. A unique default name is assigned automatically but you can modify this name at your leisure without effecting the position data. Finally you should hit "save" to store the waypoint in your database. The waypoint screen from the G-12 family looks like:

MARK POSITION
-------------
  Waypoint
  001    .     - default name and icon - both can be changed.
N 39 15.395'
W121 02.166'   - current position - not editable here.
-------------
Add to route
number __      - You can add a new waypoint to a route here.
-------------
 +/- __._FT    - used with averaging to indicate FOM
-------------
AVERAGE?       - averaging available on newer units
SAVE?

On some units there is an averaging feature. If you are standing still you can click 'average' on the waypoint save screen and the Garmin will start taking readings to average with the one that was captured when you hit the MARK key. Averaging will continue until you finally select save and enter. While averaging is going on the unit will display a FOM, figure of merit, number to indicate the probable accuracy of the average to this point. On the G-III family and emap you first save the waypoint and then you can average by selecting this option from the local menu on the waypoint display screen. (Please see more information on averaging below.)

If you are using dgps you can still average the position but the improvement will be much less since dgps is already more accurate. Averaging still can reduce the some of the effect of a temporarily poor DOP. While averaging is going on you can move to the name field and enter the name you wish so that when you have achieved a stable FOM you want you can save the results.

Man Overboard

All units except the aviation models, the etrex, and emap have a man over board (MOB) capability. This is accomplished by pressing the GOTO key (Nav key on the 76) twice in a row and then hitting enter. This will store a special waypoint at your current location named MOB and will automatically start the navigation features of the unit to aid you in navigating back to that point. A position marked in this way is designed as a safety feature for boat use when someone might actually fall overboard. You may find other uses as well such as when your hat blows off you head driving down the road. If you want to save that location then you should rename it since it will be overridden by the next MOB sequence.

Accuracy Considerations

The accuracy of a particular fix is dependent on a number of factors. For example if the satellite geometry is poor the solution will be inaccurate. Satellites close to the horizon will have good satellite geometry when coupled to one high unit but they suffer from atmospheric effects which can make the accuracy worse. These factors are taken into consideration when the unit reports the estimated position error, EPE on the Satellite status screen. You should consult this information to determine just how good the fix is. In addition the G-III family reports a Horizontal Dilution of Precision, HDOP, number near the vertical bars on the satellite status screen. (Some other handheld units can also display this information using undocumented commands; see the chapter on secret commands for more details.) The HDOP number is unitless where higher numbers indicate a worse fix. For a 4 satellite solution a 1.0 would be considered to be an excellent geometry and anything below 2.0 would be great. When there are more than 4 satellites available that can be used to compute a solution the older multiplex units will pick the best 4 for the computation. They will also track 4 more so that as satellites move or the unit moves into new positions a selection of the best four can be made and switched as necessary. Switching to another set of satellites can, of course, effect the EPE accuracy. The newer 12 channel units automatically use all of the available satellites so they tend to effected less by this kind of change. Using more satellites is called an overdetermined solution and can result in a DOP of less than 1.0. The meaning of Garmin's EPE number is not documented and it seems to vary for one model to another and even from release to release. With the latest units it seem to reflect a probability from about 50% to perhaps as high as 63%. That is 50% of the time you will be more accurate than the EPE shown but 50% of the time you could be worse. This, of course, is only an estimate but a more conservative approach would be to double the EPE number and expect to be within that accuracy range about 95% of the time.

All of the data above is reflective of horizontal accuracy. Vertical accuracy is generally 50% worse than horizontal accuracy but is not reported in the gps. This is primarily due to the difference the DOP for a vertical geometry. Many folks are disappointed with this level of accuracy since they often know their approximate altitude and can judge this inaccuracy much easier than they can the horizontal accuracy. If you only have a 2D fix then the most recent altitude setting is used to compute the horizontal fix and if this altitude setting is wrong the horizontal position can be much further off. If you only have a 2D fix you should check and adjust the altitude manually as required to ensure an accurate fix. This can be set on the position page either directly by displaying and selecting it or on the G-III family and emap from the local menu.

If you augment your gps with a DGPS beacon receiver you can negate most of the atmospheric effects. As a result the accuracy of a DGPS is improved to 5 meters or less depending on the distance between you and the beacon transmitter. A beacon transmitter uses its precisely known location to correct for receive errors and then sends this correction data to your unit. For DGPS to work you need to be able to receive some of the same satellites as the beacon transmitter so that a differential fix can be achieved. In the US the coast guard operates beacon transmitters which are available over much of the country with an effort currently in progress to cover the entire USA. Many countries around the world also have beacon transmitters. However, if you are in a area not covered by these free beacon transmitters or would prefer a receiver that is not a bulky as the standard beacon receiver/antenna combination there are also DGPS services being offered using FM radio frequencies and even directly from overhead satellites. Unfortunately these kinds of services are not free.

Note that DGPS not only improves the horizontal solution but also the vertical solution subject to the same 50% degradation due to satellite geometry.

The latest technology for DGPS is called WAAS (EGNOS in Europe) and is available on the newest units. Please see the miscellaneous chapter for more details.

Averaging Techniques

This section is a little more advanced than others in this chapter. Skip this section if your not ready to dig into accuracy issues.

If you don't have a DGPS solution available you may still be able to achieve a better than 17 meter solution (the Garmin spec) by the use of averaging. The idea of averaging is to leave the unit stationary and collect multiple solutions and then average them to obtain a better answer. This can be done with the unit itself, collecting data for later computer or manual analysis, or by hooking it to a computer and collecting the data in real time directly on the computer. If you want to average altitude data you must use an external computer since there are no altitude averaging functions inside any Garmin unit. (An exception is the emap and the 76 family.)

If you don't have an averaging function or can't stand still long enough to use and you still want to perform position averaging then use the tracklog. Set the sample interval so that the tracklog won't overflow in the time you want to average and let the machine collect the data. Depending on the model unit you have you will have 768, 1024, or 2000 samples when the log is full. Any of these are plenty for our purposes. The tracklog can be downloaded to a computer for analysis or you can perform an unscientific analysis right on the screen. Switch to the map screen and zoom in as far as you can while maintaining all of the points on the display. Now use one of the techniques described below to place a new waypoint in the center of all of the tracks by visually weighing the distribution.

This trick can also be used on tracklogs collected while moving. Suppose you keep a log of several days trips to work and back. You will be able to visually see a distribution at every turn in the route. Assuming the log doesn't overflow and erase your previous trip you should be able to place a waypoint on the map page that is a reasonable average of the trips. You can selectively turn the log on and off to make this a usable method of obtaining an average using the machine itself. Similarly you could collect multiple waypoints over a long period and visually average them to obtain a better solution or use a computer to analyze the waypoints after downloading them. If you use this technique be sure you take them several minutes apart and don't expect great accuracy unless you are willing to collect a lot of points.

Averaging can be done even with a pencil and paper. Generally setting the grid to UTM can make this a bit easier but the idea is to record the location data every 30 second or every minute for a short while and then average the data you recorded. Even 15 minutes of data will improve the location somewhat. Data recorded over a longer interval or will more separation is usually better so you could record several wapoints over several days or even weeks and average them later.

By the way, if you are watching the FOM (figure of merit) while averaging and it starts to creep up instead of down, perhaps you just experienced one of these anomalies of a fix that is based on information outside the 95% window. Perhaps, if you have time, it would be wise to cancel the waypoint and start over.

Planning Ahead Waypoint Entry

Waypoint entry can be entered several different ways without actually visiting the location or after the fact from collected data.

Entering Known lat/lon Values

If you know the lat/lon for a position you can enter it directly as a new waypoint. There are several ways to enter a new waypoint but the most straight forward is to follow these steps:

  1. Go to the main menu and select waypoint.
  2. Select New from the 'on page' menu. (Remember that you can use the up arrow key to reach the bottom of the screen.)
  3. Enter the new name and the lat/lon entry. You should have the same datum and coordinate system selected that matches the information you are trying to enter.
  4. If your machine supports icons you can select the one that most represents the waypoint you are creating. See below for information on icons.
  5. Select done when you are finished.
This diagram is for a G-12 family or older multiplex unit. The G-III family is similar.
   WAYPOINT
-------------
______ .        - Waypoint name and icon
_  __%__.___'   - Lat/Lon
_ ___%__.___'
_____________   - User definable comment 16 characters long
-------------
REF: ______     - Projecting a waypoint from a known waypoint.
 BRG   DST
___   _.__MI
-------------
RENAME? NEW?    - Commands
DELETE? DONE?

Some units such as the etrex or emap do not have a direct method of entering a new waypoint. On these units you begin by adding a waypoint at your current location, but instead of saving it as you normally would you change the coordinates and then save it.

Projecting a Waypoint

Even if you don't know the specific coordinates you can still enter a waypoint by using the waypoint entry screen to project the new waypoint from an existing saved waypoint on units supporting this feature.

  1. Go to the main menu and select Waypoint.
  2. Select NEW and pick a name for your new waypoint.
  3. Move to the REF keyword, hit enter, and key in the old waypoint name you wish to use as a reference for the new waypoint.
  4. Enter the distance and bearing to the new waypoint.
  5. Pick and icon for your new waypoint.
  6. Select Done to complete.

Generally the distance and bearing will be obtained by consulting a map. By repeating this process you can enter several waypoint all based on projections from a known point or from each other. It is also possible to project waypoints from your current position. Your current position waypoint name is ______ (6 underscores). Highlighting the REF keyword area, hit enter, move the cursor to the left of the left most character to clear the field. This will select the current position as the reference waypoint; proceed as above.

The etrex does support this feature however the method of implementation is different. On the etrex Select an existing waypoint instead of a new one. Then bring up the local menu. The screen shown below will appear. Select the "Project Waypoint" and a new page will appear that looks like a waypoint entry page except that two new entries are included near the bottom of the page. Enter the new name, icon, distance, and bearing to this new waypoint as referenced to the existing waypoint that was used to get here.

Using the Map Screen to Enter Waypoints

The map screen can be used to graphically enter a new waypoint. You can visually view a location on a map on units so equipped or view a tracklog to determine the optimum setting for a new waypoint. The current zoom setting will determine the accuracy of this kind of waypoint addition so you should set it to as high a zoom setting as is practical. There are two techniques that may be used for entering a waypoint graphically. Both techniques require that you pan to the point where you want to place a waypoint. Just use the arrow keys to pan with the GIII series and emap or enter the pan mode on the other models. Zoom in to achieve the desired degree of accuracy. (The basic etrex has no pan mode and cannot use this method.)

Method one is to hit the mark key and you will get the standard waypoint entry screen. Define the data and hit enter to create a waypoint at that point. Here is one area where the G-III family and emap is not consistent with the rest of the Garmin units. Hitting the ENTER key briefly will create a waypoint at the panned position but holding the ENTER key down for long enough to MARK the position will actually enter a waypoint at your current location instead of the panned location. Be careful here and make sure you got what you wanted. In this way you can directly name the waypoint and assign an icon prior to saving it.

Some units may select a point on the map, called a mappoint, instead of creating a new waypoint. On these units you can convert this mappoint to a standard waypoint by using the local menu and select the convert to waypoint.

The second method for units with a goto key is to pan as above and hit the GOTO key. This will create a waypoint with the name of "MAP". Hitting ENTER at this point will actually cause you to enter a navigation mode with the MAP waypoint as the target destination. However, the MAP waypoint is otherwise like any other waypoint. It will exist until it is manually deleted or replaced with another MAP entry by repeating this procedure. For this reason, if you want to keep the new waypoint you just created you should rename it.

It may also be possible to project a waypoint using the map screen although accuracy may be a bit less. Use the ability to read the direction and distance from your current location while panning to set a new one.

Updating Waypoint Data

One of the things that happens regularly when entering waypoints from maps and other sources is a need to update them when you finally get there. On some older Garmin units this is easily done using the REF keyword on the waypoint page. (The etrex and emap do not have the REF section and cannot use this method, however they have other methods.) It can even be done on the fly while driving past the location. Use the following steps.

  1. Go to the main menu and select Waypoint.
  2. Toggle in the name of the Waypoint you wish to change.
  3. Move to the REF keyword area and hit enter; ensure the waypoint name is all underscores (move the arrow key to the left until this appears).
  4. All underscores is you current location. If you are moving you can watch dynamically as the distance and bearing change to track your movement relative to the waypoint you have selected. (Note that this is a good way to note the distance to the waypoint.)
  5. Select the distance field and clear it to zero. (Use the left arrow key again.)
  6. Wait until you get to the exact point you want and hit enter.

You have just updated the waypoint location on the fly. This is also an excellent way to move waypoints. I use this technique quite often to shift trackback waypoints to a more meaningful locations. You can actually do this on waypoints that are part of an active route.

Other Updating techniques

The newer etrex units have solved this problem of updating with a special entry in the local menu. On the right is a picture of the venture waypoint screen shown after selecting the local menu entry. Selecting the choice "reposition here" will update the waypoint to the current location.

On units that support averaging an existing waypoint such as the III series and the emap the way to update an existing waypoint after you arrive is to simply select the waypoint and average it for a few samples. This will move the waypoint to the current position.

Special techniques on mapping units

If your unit supports viewing the waypoint on the map screen you can select it while viewing using the enter key and you will be placed in a move mode where you can graphically move the waypoint.

  1. Bring up any waypoint. (It can be selected in panning mode from the map page or in any other method used to view the waypoint.)
  2. Bring up the local menu and select SHOW MAP
  3. Press ENTER on any waypoint and you will be placed in move mode
  4. Use the cursor to move the waypoint as needed
  5. Press ENTER to complete the move.
  6. You can move others as well.
  7. Press Quit to leave move mode.
This is a very handy technique to align waypoints with a road on the map on otherwise fixing waypoints that you have entered via another program. Be careful when using this technique that you don't accidently move a waypoint. When you are panning to select a waypoint with the cursor keys the selection will happen prior to actually getting the cursor to the exact center of the waypoint. It you hit enter the waypoint will be moved so that the exact center of the waypoint is where your cursor happened to be when it was selected. If you were zoomed out at the time you could move the waypoint by a significant amount.

Renaming waypoints and changing icons

Waypoint names can be updated using the Rename function on the Waypoint page if present. Do not just select the name field and change the name. If you do this you will just make a copy of the existing waypoint under the new name. On units without the rename function the waypoint name can be edited directly. All Garmin units except the etrex and emap have a comment line that can also be edited just by selecting it and toggling in the new data. The default comment is the date and time the waypoint was created using UTM time. Often this is what you want but other pieces of information could be street address of the waypoint or altitude. The emap and etrex have an actual altitude field that can be edited in this fashion.

You can change icons, if this is supported on your unit, by just selecting the waypoint icon on the waypoint page. This will bring up the icon page. Select the desired icon and whether the text you wish to be displayed on the map page. Choices include no text, name, or comment. Choosing comment permits you to show waypoint names as long as 16 characters on the map screen.

The different models from Garmin have differing numbers of icons and differing types of icons. The most basic units include 16 different icons which are usually sufficient for most usage. Two will be used by default. All waypoints made by you will default to the small dot icon and all waypoints created by the computer as part of a trackback will use the Temp icon. On the G-12 family and G-II+ this is a small T surrounded with a filled circle. On the G-III family it is a set of foot prints. I would recommend that you never use this icon yourself so that you can readily see the temp waypoints.

My favorite icons:

Others include the fish, anchor, wreck, poison, circle x, and deer. You may use these but I seldom do. Some folks mark their fishing spots, keep away from (proximity) waypoints, and use the cross for hospitals and the circle X for intersections or train crossing. You need to develop your own conventions and then stick to them. Units that support maps will tend to more icons and have standard map symbols for icon use. Some have as many as 75 different icon choices.

You can also use the main waypoint screen to change the values present on the waypoint data itself or the comment by selecting and modifying them directly. For waypoint that have a specific street address, this information can be placed here, or perhaps you might want to enter the altitude. Units that support altitude in the waypoint generally do not support comments.

Viewing Waypoint Data

Waypoint information can easily be viewed from the main menu by using the waypoint command. Once entered the waypoint screen will appear with some waypoint selected or perhaps a totally blank screen. To select the waypoint you want to view you need to toggle in its name by selecting the waypoint name field and then using the arrow keys to select the name you want. Use the up/down arrow directions to pick the letter or number and the right arrow to move to the next letter. The Garmin has a feature that attempts to fill in the waypoint name for you based on the first waypoint name that matches the letters you have toggled in so far. However, it is easy to skip over names without noticing. For example, suppose you have waypoints named ANDY, APPLE, BANANA. You enter A and ANDY shows on the screen. If you were to continue to toggle the A to B you would see BANANA but you might not know that APPLE was even available. To reach APPLE you must key A and then move to the second letter and change it to a P to see APPLE.

You can also view a waypoint from many of the screens that permit you to select a waypoint. For example if you highlight a waypoint on the map screen or on any of the route screens you can hit enter and review the contents of the waypoint or work with that waypoint. From the main menu page there is a waypoint list menu item. This list can also be used to select a waypoint for viewing or editing. On the 12CX the menu list is augmented with a tab system that lets you get to a particular waypoint more easily.

On units that have a find key you would view a waypoint by using the find key and then selecting waypoint. You can view the full list or the nearest list which supports up to 15 nearest waypoints on the emap. (They must all be within 82 miles to be seen.) There is also a favorite list on the advanced etrex models that lets you build of list of favorites for rapid viewing at any time.

Your Garmin keeps track of 9 waypoints (15 on the emap) that have the special significance of being the closest waypoints to your current position. These waypoints are displayed on the map screen and are available in a special list from the main menu. This can be a big help if you get lost and need to find the closest place near where you are currently located. Waypoints beyond 100 miles will not be shown even if you have less than 9 available.

Some of the waypoints are visible on the map screen. On mapping units you can use a local menu item on the waypoint screen to switch to the map view so that you can visually identify the waypoint. On the emap and etrex this is a button on the waypoint screen. On all units the nearest nine waypoints are visible on the map screen. If you want to view a waypoint that is not in the nearest nine you could use the simulation mode to move your position so that it will be visible. Another technique is to use the 'goto' command to set up a temporary goto. This will make it visible and draw a line from you current position to the waypoint to help you find it. If you are viewing a waypoint, on have it highlighted in a list then this will be the default target for a goto which make this technique much easier. Finally, if you need to view several waypoints that are not in the closest nine you can create a route of up to 30 waypoints. If this is activated they will all be visible on the map page.

The etrex can display all the waypoint on the map screen which can cause clutter so you have an option to turn some of them off. The emap will display up to 15 waypoints but when you scroll the screen the 15 waypoints chosen will be the closest to the cursor instead of being based on your location as in the other units.

Deleting Waypoints

The rules that permit deleting waypoints is quite a bit different between the various Garmin units. This is by far the biggest difference in these units. Generally you can delete waypoints from the waypoint page by using the delete option but there are conditions that won't let you delete some waypoints. For example, none of the units will let you delete a waypoint that you are currently using as the destination for navigation.

The older multiplex units won't let you remove any waypoint that is part of a route. To remove one of these waypoints you need to first remove it from the route or routes that it is in. On these units the waypoint list includes one route number if a waypoint is in a route. So, you would find the waypoint in the list and note the route number prior to attempting to delete it. This information is displayed where the icons are displayed on the later units. Removing a route or removing a waypoint from a route has no effect on the waypoint itself.

The 12 channel units have relaxed the rules for removal considerably. On these units you can remove a waypoint and it will automatically be removed from any routes that it is part of. The etrex and emap warn you that the waypoint is part of a route and you can then choose to remove it or cancel. You cannot remove a waypoint if it is currently the destination point for a goto or is defining the current leg of a route you are using. On the G-12 family temp waypoints created as part of a trackback will automatically be removed if they are no longer part of any route and a new trackback is initiated.

There are also commands for removing multiple waypoints. At the bottom of the waypoint list there is a "delete waypoints" command. On older units this will remove all waypoints not part of a route. On newer units this will invoke a submenu permitting removing all waypoints or all waypoints that are using a particular icon. On the later releases of the G-III family you can further distinguish removal by specifying all waypoints using a particular icon that are not part of a route.

The GPS V does not seem to have an easy way to delete all waypoints. Here is a work around to delete all of the waypoints. Use the Find command and select waypoints by name, press the page key, then hit the menu key and select delete all.

Distance to Waypoints

You are often interested in measuring the distance to a waypoint or between waypoints. Here are a few techniques. Some also tell you the bearing to between the waypoints too.

Proximity Waypoints

Proximity Waypoints are the same as any other waypoint in your waypoint database. However, some Garmin units, the G-12 family and the 76 family permit you to use waypoints in a different way. These units have an alarm that can be set to indicate when you get within a defined radius from these waypoints. Most commonly you would use this to indicate a warning when you got to close to a sand bar or other obstruction when boating, but there is no reason you couldn't use them to let you know when you were in CB range of you home or within radio reception range of a favorite radio station or perhaps any other use you can imagine. Proximity alarms are separate and independent from the arrival alarms that can occur when you are using goto's and routes.

To set a proximity alarm you would go to the main menu page and select proximity waypoints. You then add a waypoint from your list of existing waypoints and add the distance from the waypoint. Whenever you are within the radius defined you will be alerted. To disable that alarm set the distance to 0 or remove the waypoint from the list. Alarms are both visual (with an alert box) and audible, except on the G-12. At night if the lamp has timed out it will flash on as an additional visual warning.

Tips and Tricks

Tip 1 - Averaging an existing Waypoint

It is not possible to use averaging when updating a waypoint, on the 12 family or II+, since the averaging selection is only on the new waypoint screen. If you have an existing waypoint that you want to update but it has comments or a long name that you don't want to re-enter you can build a new waypoint with a simple name like "a". Average it as much as you need to. Then bring up the waypoint you want to change and set it to reference the new waypoint "a" and set the distance to '0'. Hitting enter will change the existing waypoint to use the new waypoint's position. Now delete the "a" waypoint.

Tip 2 - making waypoints from the city database

It is possible to create a waypoint from the city database. If you select a city on the map, or map screen, and then hit the "mark" command you will create a user waypoint that is derived from the city one. The emap does not have a mark key but any object on the map can be converted to a waypoint using an entry on the local menu after you select the object. Note that the emap, etrex, and 76 units can use a mappoint selected from the map in a route without having to first convert it to a waypoint but on older units it must be a real waypoint to be in a route.

Tip 3 - returning to a previous waypoint

One way to partially defeat any inaccuracies and return to you exact fishing spot is to store your waypoint, averaged best you can. Then take two bearings of prominent objects using a hand bearing compass. Store the bearings as part of the comment or in a separate notebook. (Storing just the two bearings should be enough if the prominent landmarks are really prominent.) Now when you return to the spot you can use the bearings to help locate the exact position.

Tip 4 - Triangulation Technique

Let's suppose you can see some point off in the distance that you would like to navigate to but you don't know its distance. With the use of your gps and an external hand bearing compass (or the built-in compass on the summit an vista) you can triangulate and find this destination waypoint. The method will be to build a route and then use the display of the route on the map screen to pinpoint the desired location. Here is how to proceed:

  1. From your current location mark a waypoint.
  2. Taking a bearing with your compass to the desired point and use the waypoint editing page to add a new waypoint based on bearing and distance from your current position waypoint. You will just estimate the distance, so pick a distance that is further away than you expect the point to be. (On the Vista and summit you just do a sight n go command and the "Site n go" waypoint is built automatically, rename it for the next step.)
  3. Begin to build a route by starting with the new waypoint you built out of the bearing and the second entry should be the current location waypoint. This is just a temporary route so build it on the route planning page on the G-III family or on route 0 for the other products. See the route chapter for instructions on entering a route. Note that adding a waypoint entry to route 0 will automatically cause the active route page to appear in the rotation so use this page when you need to add further waypoints.
  4. Travel to a second point some distance from your current location where you can get another bearing on the distant point. Repeat steps 1 and 2 for from the new location. The further you travel the more accurate the answer is likely to be.
  5. Add the now current location to the next entry in the route and finally add the new projection to the route. You should now have 4 locations in the route.
  6. On the G-III family you need to activate the route on the planning page but on other units it is already active since you used 0 to build it.
  7. Look on the map page and you should see a route that looks something like a child's drawing of an indian teepee, a base for a triangle and two lines extending from each end of the base and crossing somewhere on the screen. This crossing point is the desired destination.
               \ /
                X   <-- destination
               / \
              /___\
    
  8. Use the panning capability on the map screen to move the cursor location to the intersection point found in the previous step and zoom in for the most accuracy.
  9. Hit the GOTO key to create a new waypoint called MAP at that point. Your gps will now be navigating toward this destination. Or just use the enter key if you don't want to navigate to that point.
At this point you can get rid of the active route, remove the temporary waypoints and use the navigation screens to goto the new waypoint or to compute the distance to the new waypoint. -- based on a technique posted in the sci.geo.satellite-nav news group.
Tip 5 Reading current lat/lon and altitude

The emap and etrex will provide information about your current location but it may take several key strokes to get at this data. It is often easier to press and hold the enter key to bring up the waypoint screen. This will show the current location and altitude. If no other keys are entered this waypoint can be canceled (esc on emap, page on etrex) when you are finished looking at it. This trick will work on any unit, of course.

Tip 6 Seeing more waypoints on the screen.

Many Garmin units restrict the number of waypoints that a visible to some number. On some units it is 9 (older units) while some have 15 (emap). On these units you can view more waypoints on the screen by making and activating a route. All the waypoints in a route are always visible.

Tip 7 Getting new waypoint icons

Units that support maps and poi data may display icons for this data that are not available within the standard icon list for a waypoint. It is possible to use these icons for your own waypoints. Here's how:

  1. Display a mappoint (poi) containing the icon you wish to use.
  2. Convert the mappoint to a waypoint.
  3. Edit the name and location data to the location you wish for your new waypoint but don't touch the icon.
  4. Save your new waypoint.

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Revisions
99/5/21 Created 9
99/6/22 Updated view waypoint data and added tips section
99/7/1 Added more tips
99/7/5 Added G-III move mode to edit waypoints section
99/7/30 Added map waypoint creation, accuracy discussion, averaging discussion
99/8/19 Added new tip on triangulating a position. Added more to averaging
00/1/9 fixed error in dgps accuracy, added distance tip.
00/5/1 removed SA discussion
00/8/10 added emap and etrex discussion.
00/9/2 added etrex projection.
00/10/9 added emap/etrex tips. added auto name discussion
01/7/16 updated some data.
01/9/20 added tips.
01/11/12 added section on distance to waypoints.
02/07/23 added gps V data on deleting waypoints.
02/08/09 added tip on new icons.
03/04/08 added venture figure and text.