Charts and Challenge Mystery Cache
Hidden : 8/21/2004
Difficulty:
4 out of 5
Terrain:
1.5 out of 5

Size: Size: regular (regular)

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Geocache Description:

This is a cache that uses some nautical navigation skills and some basic math skills. I hope this provides a bit of a challenge. Ignore the above coordinates; they indicate that this cache can be found in Victoria BC. Though, from this point you can see at least two positions mentioned in this cache. A nautical chart might help, and don't trust your basemap! (All critical info can be found online.)

Pay attention to units. At the end of each step there is a way to avoid compounding any errors that might have been made (if you are close enough).
Step 1:
a)Find the following three points, they are all fixed nautical lights (note: you do not have to visit these points to solve the mystery!):
 Point A is at:
  • 1.018 geographical miles from Brotchie light 
  • 265.300 degrees from Fiddle Reef light 
  • 212.505 degrees from Zero light 
Point B is at:
  • 240.917 degrees from Discovery Island light 
  • 183.941 degrees from Zero light 
  • 101.986 degrees from Brotchie light 
Point C is at:
  • 27.571 degrees from Discovery Island light 
  • 44.789 degrees from Fiddle Reef Light
  • 94.316 degrees from Zero light 
b)If you've made it this far you probably know how to eliminate the error. It is very important that you do! (ie get the exact coordinates for the three points - if not see the hint)
Step 2:
a)Project a waypoint:
b)Follow these instructions to determine the heading:
  • Determine a heading that bisects angle ABC. 
c)Follow these instructions to determine the distance:
  • Determine the area of the triangle ABC (International nautical miles squared) 
  • Use the number obtained by the area calculation to one decimal place (don't worry about the fact thatyou are using squared miles). 
  • Multiply the area by 0.220174418 and you will have a distance in international nautical miles. 
d)Project the waypoint from point 'b' using the above heading and distance
  • Go to the waypoint. 
  • The waypoint should lie on a road. Within 200m of the point (on either side) should be places to park an automobile. 
e)Walk along the radial towards point 'b'. You should come across a bench. Sit down, let your brain rest and your GPS get a good fix. On the bench is the name "Trudy Carson"
f)With this bench found, you will have no errors for the next step.

Step 3
a) Use the coordinates of the bench (we went to the bench three times, got a fix with +/- 6m accuracy and averaged the three) to project a waypoint.
b) Follow these instructions to determine the distance:
    i)use 228.7695
    ii)How many feet are in the unit of depth on American nautical charts?
    iii)How many cables are there in half of a sea and/or nautical mile by definition? (whole number and precisely no decimal places)
    iv) From answer "i", subtract the answer "ii" multiplied by the answer "iii", subtract "iii", and finally subtract 0.2194667. The answer is the distance in metres.
c) Follow these instructions to determine the heading:
  • Determine the average length of a sea mile in metres at the closest parallel of lattitude in which you find yourself, to two decimal places. (Be careful how you answer this question make sure you average over a full degree at the parallel. The hint can help you check your answer.) 
  • The number you get is 6 digits long. The following 6 letters correspond to the number you just calculated: "abcd.ef" 
  • Using the above correspondence, the heading you are looking for is: "dcf.acd" degrees. 
d) The cache should be at this waypoint. Contents at time of hiding:
  • Boatswain's pipe(whistle) 
  • Regular whistle
  • compass/thermometer/magnifying glass/whistle
  • emergency blanket -non-activated travel bug 
  • geocaching tatoos 
  • coin from U.A.E.

Additional Hints ()

-[Step 1]: Gur Pnanqvna Pbnfg Thneq choyvfurf n yvfg bs anhgvpny yvtugf. -[Step 2]: Gur angvbany trbfcngvny-vagryyvtrapr ntrapl bs gur Havgrq Fgngrf unf Angunavry Objqvgpu'f "Gur Nzrevpna Cenpgvpny Anivtngbe" ninvynoyr sbe serr qbjaybnq. Vg fubhyq uryc jvgu havgf. -[Step 3 (c)]: gur fhz bs nyy fvk qvtvgf vf gjragl svir. Objqvgpu unf n gnoyr bs gur yratguf bs qrterrf bs yngvghqr. -[Location] Haqre n gerr naq haqre n ebpx arne n cvpavp gnoyr.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)

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