Setting First Cache

[+kbootb]

I'm planning my first cache, a bit of a multi with a final real cache.

 

I have been over the route 3 days running but find that each day I am getting readings that are 70 to 100 ft out from the previous days.

 

There is clear view of the sky, and the Garmin is telling me that is accurate to 20 - 30 ft each time. I intend to keep visiting the site and averaging each time till I think it looks ok, but is this sort of variation normal? How accurate do I have to get things before I can post them with confidence?

 

Also, is there a description anywhere of the terrain and difficulty ratings that should be used?

[+Pharisee]

Try this site for your cache difficulty and terrain rating.

 

As for the variations in GPSr readings... yes, it's normal Give it your best shot and if you're still unsure, put a note on the cache sheet asking the first few finders to e-mail you the reading they got at the cache site. You can fine tune it a bit later if you think it's necessary.

 

The first cache is always the worst.... but a few positive cache logs and it will all be OK.

Just go do it !!!

[+klaus23]

As stated above, the first one is always tough.

 

I planted a four-stage multi as my first cache, and the problems were endless.

Firstly, I used the wrong datum. Then, the first film canister (one of four before the main cache) was in an area with tree cover. The second was in a stone wall.

Between the third and the fourth lay a golf course. of course, I did not know that cachers would persist in walking right across it.

And to cap it all off, the main cache was nicked a few weeks on.

Currently it's back to an ordinary cache, I just could not face the problems.

 

Speaking from experience, I would hold off on a multi-cache until you've cached a little. The reason is that you could do a few multi's and find out what makes a good one. And then go back and make your own.

 

Best to plant a relativly straightforward cache, start small, then get bigger.

[+Subarite]

I agree with Pharisee - GPS is not an exact science and experience of what is right and what is not takes a little time.

 

Why not just go for a straight forward traditional cache to start.

 

GPS reception is variable - changing during the day according to the Satellite constellation and even more significant is the amount and direction of the tree cover. This is very significant at this time of year and can make getting a good fix nye on impossible.

 

I hope this helps (probably doesn't...)

 

Andy.

[+Pengy&Tigger]

We usually take a few readings once it is hidden, by walking away and coming back a few times. We usually then take an average of the readings then put the co-ords back in the GPS. We then walk away quite a bit and use the co-ords to try to find it. If it takes you roughly there then you have it.

 

If you get a lot of variation then add a good hint to make sure it can be found. There's nothing worse than getting a DNF half way through a multi.

 

Pengy & Tigger

[+John Stead]

Pengy & Tigger give very sound advice.

I would add one further suggestion and that is to let the GPSr settle for a minute or so when you stop moving. If you have the coords showing you should see when they settle down, sometimes almost at once, sometimes after a little while depending on the quality of the signals received.

[+Papakas]

Pengy&Tigger's method is the way to do it! They've successfully set up some very accurate caches as a result. Any difficulties, as they advise, balance the co-ords with a suitable hint. I've placed a mystery cache in woodland too dense to get a decent GPS fix so I've as good as given a step by step explaination of how to get to within 20 metres of it. That's not too large a search area! Good luck!

[+Naefearjustbeer]

I normally mark a few waypoints approaching the cache from different directions. Then I will also leave the gps sitting on top or as close as possible to the exact spot for about 5 mins and then mark a waypoint. If you still think that you are not getting good accuracy for the co-ordinates give a good clue and even a clearly marked spoiler photo

[markandlynn]

We usually take a few readings once it is hidden, by walking away and coming back a few times. We usually then take an average of the readings then put the co-ords back in the GPS. We then walk away quite a bit and use the co-ords to try to find it. If it takes you roughly there then you have it.

 

If you get a lot of variation then add a good hint to make sure it can be found. There's nothing worse than getting a DNF half way through a multi.

 

Pengy & Tigger

Thats how we did ours. We walk in from about 20 ft away (the accuracy of your GPSr) from hopefully 8 different directions. I then type the waypoints into excel and calculate the average.

[+Pharisee]

When I'm setting a cache or need a waypoint saved for any reason, I normally use my old Garmin GPSIII. This has an 'averaging' feature that records the co-ordinates once every second and displays the 'running average'. I'll usually leave it sitting on the cache or as near as I can get it and let it run for at least 5 minutes, most times it's longer. That way I get the average of at least 300 separate readings. I'll do that for at least two, probably three separate visits on different days and compare the results. There's never been a difference of more than 5 on the least significant digit and as far as I'm concerned, that's good enough.

The problems arise when you come steaming in on a cache hunt and don't give the machine a chance to settle. I did a cache recently where the last few logs had all reported that the GPSr was reading was over 100 ft adrift. The cache was under fairly heavy tree cover and I got the same result... 108 feet out. I left mt Legend on a stump while I was doing the log book stuff and as I watched, the GPSr reading gradually came down and after 5 minutes it was telling me that the cache was just 8 feet away!!!

The moral... give the GPSr some time, specially under adverse condition.... don't just keep walking round in circles trying to follow the arrow.

[+The Hokesters]

Thats how we did ours. We walk in from about 20 ft away (the accuracy of your GPSr) from hopefully 8 different directions. I then type the waypoints into excel and calculate the average.

Any chance of publishing the formulae you use in Excel for us math donuts?

 

The Hokesters

[+The Hokesters]

The moral... give the GPSr some time, specially under adverse condition.... don't just keep walking round in circles trying to follow the arrow.

That's what I've been doing wrong - D'oh!!!

 

Boy am I dizzy

[markandlynn]

Thats how we did ours. We walk in from about 20 ft away (the accuracy of your GPSr) from hopefully 8 different directions. I then type the waypoints into excel and calculate the average.

Any chance of publishing the formulae you use in Excel for us math donuts?

 

The Hokesters

I can email the spreadsheet, just let me know which version of excell you use. This goes for anyone else who wants a copy. I use the average command to do the sums as i sometimes take more readings than 8 . Syntax for sum is

=average(A1:A10) you will need to use separate colums for each part of the coordinate as excell will not average cells formatted as h.mm.ss.

[+The Hoffies]

I just like to say a big thank you to kbootb for asking the question. The info in this topic is brilliant as we are also looking to place our first cache. I feel a lot happier already!

 

Happy caching!

[+DomHeknows]

i'd say place a couple of normal caches before a multi as multi's have at least twice the capacity and likelyhood to go wrong (and mine did!). That and you put a lot of effort in and not as many people visit it.

As to averaging, a good clue (not TOO easy though) and description helps this and you can always up the difficulty if your co-ordinates are way out and the first few finders will tell you if your co-ordinates are out. One benefit of having inaccurate coordinates is to slow down the FTF'ers :-)