Triangulation 1 Multi-Cache

• The intent of this series of geocaches is to help us learn how to apply triangulation techniques to find the location of unknown points using a handheld GPSr.
• While these geocaches were created and tested using a Garmin GPSr, they can also be found using a smartphone or other device with the appropriate software.
• It is recommended to find this series of geocaches in numerical order (1-6) as each geocache builds on techniques and information learned in previous finds.

The Oxford dictionary defines Triangulation as "(in surveying) the tracing and measurement of a series or network of triangles in order to determine the distances and relative positions of points spread over a territory or region, especially by measuring the length of one side of each triangle and deducing its angles and the length of the other two sides by observation from this baseline."

In practice, 'Triangulation' is actually a generic term commonly used when referring to several surveying terms:

• Triangulation refers to the process of determining the location of a point by forming triangles to it from known points, using only angle measurements.
• Trilateration (True Range Multilateration) is a method of determining the location of a point using multiple known distance measurements from known points.
• Triangulateration involves the use of both angle and distance measurements to determine the location of a point.

To find the final location of each geocache in this series, we will actually be using Triangulateration, which is a combination of both Triangulation and Trilateration.

Additional information can be found at GPSrChive > How To... > Triangulation.

While the procedures provided in this geocache series are not mutually exclusive, and exploring additional techniques to solve each problem is encouraged, please be mindful of accuracy limitations imposed when using consumer grade equipment to perform these exercises.

Triangulation 1 - Waypoint Projection

The location of the first geocache in this series will be relatively quick and easy to find using simple waypoint projection.

While waypoint projection alone does not actually involve any 'triangulation', this fundamental process will be employed to help locate the final coordinates for most geocaches in this series.

Waypoint projection can be a helpful navigation technique when travelling from one location to another where the destination is hidden or obscured by physical barriers along the route such as heavy foliage, dense forest, mountains, lakes, canyons, etc. 

Projecting a waypoint involves plotting a second point that lies a certain distance and direction from the first. That direction, provided as an angle in degrees from true north or from magnetic north, is called a bearing.

To project a waypoint from known coordinates in the field, follow these steps:

1. At the starting coordinates, determine the desired bearing.
   
   • When using a magnetic compass, determine if the bearing specifies true north or magnetic north. If the former, make sure to adjust for the magnetic declination at your location.
   • When using a GPSr, make sure that the north reference of your device matches the reference specified by the bearing.
2. Walk the specified distance in that direction to arrive at the projected coordinates.
   • A GPSr unit can also record a waypoint at the desired bearing and distance without you needing to walk to the location first.

Projecting a waypoint using a Garmin GPSr can be accomplished using one of two methods.

1. From another Waypoint: 
   1. Open 'Waypoint Manager' page
   2. Select desired waypoint
   3. Open waypoint option menu
   4. Select 'Project Waypoint'
   5. Enter desired bearing value
   6. Choose desired projection distance units
   7. Enter desired distance value
   8. Save 'Projected Waypoint'
       
2. Using Sight 'N Go:
   1. Open 'Sight 'N Go' page
   2. Lock desired direction value
   3. Select 'Project Waypoint'
   4. Choose desired projection distance units
   5. Enter desired distance value
   6. Save 'Projected Waypoint'

Procedure

Beginning at the posted coordinates, find a nearby park sign that is divided into three sections (top, bottom, side).

Find the four digit number on the side portion of this sign.

Discard any duplicated digits to get a new number.

Find the lamp post in this park marked with this number and save waypoint 'T1A'.

Before we can project a waypoint, we will need bearing and distance information to that waypoint.

Look for another number near the top of this lamp post. This number is 'X'.

The number of digits in 'X' equals 'Y'.

'D' = ('X'-'Y').

'F" = ('X'+'Y')*10.

Configure your GPSr heading to use True North.

Project (and save) waypoint 'T1F' using a bearing of 'D' degrees and a distance of 'F' feet.

Upon arrival at waypoint 'T1F', put down the GPSr and use your 'geosense' to find the geocache container.

Once located, the container does not need to be removed in order to retrieve the log sheet.

Please exercise special care when retrieving and replacing the log to prevent muggles from unintentionally discovering and potentially vandalizing the container.

When logging this find online, please include the brand and model of the equipment used to find this geocache.

You should now proceed to Triangulation 2, the next geocache in this series.