# Triangulation Caches

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Whats the best way to solve a triangulation cache?

Whats the best way to solve a triangulation cache?

Depends, did they give you everything you need? Because I'm personally a big fan of the ol map and compass way. Google triangulation, you'll be able to figure it out quite easily

Whats the best way to solve a triangulation cache?

Depends, did they give you everything you need? Because I'm personally a big fan of the ol map and compass way. Google triangulation, you'll be able to figure it out quite easily

Yup - map and compass works best for me as well. Although I am sure there are probably high tech websites to figure it out as well.

Yup - map and compass works best for me as well. Although I am sure there are probably high tech websites to figure it out as well.

http://www.gpsvisualizer.com/calculators

if you have a ipad or iphone there is actually an app for that.

when i found it i just searched for geocaching and there are a lot of apps that pop up.

and you can project waypoints just by adding in a set of cords telling how many feet then what direction

you can also do the triangulation on the same app

I solved a local triangulation cache by getting an approximate solution on the map, and then using a coordinates calculator to refine my guess.

Depending on the distances involved, it may or may not matter which algorithms are used by the coordinates calculator. Most use a simpler algorithm that is less precise. The triangulation cache I did required a calculator that used the more complex, more precise algorithm.

I use fizzycalc with trial and error. That's not the best way, but I don't know the best way.

I like to use the old radial intersect method. It works if you have the information of at least 3 coordintates and the distance they are from the cache. you create the circles of radius that is indicative of the distance from the cache and center those circles on the coordinates. two circles intersect on two points but three will only all intersect on one. I have used it for a few caches like that, it works for me.

Edited by Flintstone5611

It gives a coordinate for a cache then says like 65.3 feet @ 260T what's the t mean

It gives a coordinate for a cache then says like 65.3 feet @ 260T what's the t mean

260T? That sounds like someone was trying to leave a degree measurement. As in "walk 65.3 feet at heading 260". however, I have no clue what the T means. Perhaps if you gave us more information?

it sounds like its just a projection waypoint

It gives a coordinate for a cache then says like 65.3 feet @ 260T what's the t mean

260T? That sounds like someone was trying to leave a degree measurement. As in "walk 65.3 feet at heading 260". however, I have no clue what the T means. Perhaps if you gave us more information?

The T would indicate a bearing relative to True north, rather than magnetic north (M).

When you're given a set of coordinates, a bearing, and a distance, and you're supposed to figure out the end result, that's called a "projection" or "projecting a waypoint". There are lots of online tools and smartphone apps that can do this, and many handheld GPSrs also have this function built-in.

For that distance I wouldn't even bother doing the projection, assuming those directions are for the actual cache.

Hey, that sounds fun. Are there directions on how to set up a good triangulation cache? Would I make a multi, give one set of coors on line then make them find the other coords out in the field?

My triangulation cache starts with a tag that gives the direction/bearing to the cache and the coordinates to the next tag. This second tag gives the bearing to the cache and the coordinates to the next tag. This third tag gives the bearing to the cache and a hint about a landmark close to the cache. There is an easy way to solve it in this park with just your GPSr and a piece of paper. You enter each tag location as a waypoint in your GPSr, and note the directions from each to cache, and then write down the reciprocal bearing. Head towards an area near the middle of the three waypoints, and pull up the waypoint screen on your GPSr. When the bearings to each waypoint equal the reciprocal/opposite bearings you are at the cache.

It has been solved by someone using only two waypoints. Reciprocal bearing is adding/subtracting 180 degrees to the bearing (if bearing is 270, reciprocal is 90.) Or, in this case I used mils for more precision, so add/subtract 3200 mils (half of 6400 mils.) I specified true north reference. The tags are thick aluminum punched with number and letter stamps, then camo painted. I chose the cache location first, then set the tags. At all four locations, I used two brands of GPSrs, and visited on multiple days to get accurate coordinates. All the tags are on trails, but the hills add to the challenge because you cannot site from each tag to the cache, and you cannot bushwack from each tag to the cache; you have to find the right trail.

Edited by EScout

There are several different puzzle types being discussed here. Perhaps I can clarify a little.

Triangulation generally refers to finding the location of a cache from the bearings to or from at least 2 other points. It only uses angles.

Trilateration is determining the location of a cache from the distances to 3 or more other points. It only uses distances.

Projection is determining the location of a cache from a distance and bearing from a single point.

There are also variants on these; you can combine distances and angles in various ways to make mixed puzzles.

I have made myself a general-purpose solver for these kinds of puzzles, but I have chosen not to make it available for general use as I fear it would reduce these puzzles to simple a"plug-in-the-numbers" exercises without giving any understanding about the geometry. The iterative methods described using FizzyCalc are very good manual ways of doing this; with a little thought the method can converge in just a few steps.

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