Speak My Datum
This is a puzzle cache. It is not at the listed coordinates. To obtain the cache coordinates, please solve the following puzzle.
Geodetic datums are GPS-based coordinate systems used to identify precise locations on the earth. As is often the case in our non-standardized world, there are many such datums in use globally. The one we, as geocachers, are most familiar with is called the World Geodetic System 1984, or just WGS84.
There are tools for converting from one datum to another, and this makes a good puzzle-creation opportunity.
For example, start with the posted coordinates for this cache:
N 46 09.534 W 123 57.379
Copy and paste those coordinates into this tool:
Geocaching Toolbox Coordinate Converter
Paste into the Point A Coordinates box and leave the Current Datum as WGS84.
In the Convert To box, select the datum to convert the coordinates to. For this example, select ASTRO STATION 1952 (ASQ) and click Convert.
Note the coordinates for the New Datum (ASQ):
N 46 09.641 W 123 57.560
If you then treat those new coordinates as WGS84, you will be at a point 1,004 feet away from the posted coordinates.
This puzzle will take you on a quick coordinate conversion tour and pretty much follow the above steps. Bon Voyage!
The puzzle is based on an idea by Morgan671 in the puzzle Streakers SOS #11.
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Start at N 45 31.069 W 122 40.173
Using Google Earth, what is the name of the bridge you are on (one word)?
Convert those coordinates to AIN EL ABD 1970 (AINB).
Paste the New Datum coordinates back into Google Earth. What is the name of the sternwheeler boat you have boarded (one word)?
From the coordinates of the boat, walk/swim 13428178 feet (no commas) at an angle of 73.582059538347 degrees using a tool such as this one to the "other" Portland and to a very similar site. The boat you are now on is a former _ _ _ _ _ _ _ _.
From the boat, which datum moves you (almost) due west?
ACC
FAH-7
IND-7
KUS
KAN-7
From New England, pop over to old England and the center of the HMS ship permanently docked on the Thames just west of Tower Bridge.
Convert the ship's coordinates to AYABELLA LIGHTHOUSE (PHA) five times (for each conversion, copy the PHA coordinates back into the WGS84 coordinate box).
Which Underground station are you near (2 words)?
Heading homewards, fly to N 45 39.260 W 122 45.631.
What is the geographical name for this type of location where two rivers meet (one word)?
From here, which datum will move you the furthest away?
ASQ
QUO
REU
SAO
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After unpacking your bags, enter your seven answers, as one long string, with or without spaces and capitalization, into this Checker and if correct, you will be provided with the (WGS84!) coordinates of the geocache.
Enjoy the hike!
Hiking to the Cache
This is one of many puzzle caches on a beautiful hike from Coffenbury Lake in Fort Stevens to Delaura Beach Road. You can park at either end. If starting from the lake, parking is at the posted coordinates for Elvira the Elemonator (State Park fee or pass required). If starting from Delaura Beach Road, parking is at the posted for Pacific Insecticross (no fee).
The one-way distance is two miles and the terrain is almost all flat with a few small hills near the lake.