Master Mariner

A well written and well thought out argument and one that I fully agree with.

I am sorry that I could not be there in person to see you do your bit but I am working in Singapore at present so only saw some glimpses on CNN. My wife has told me she managed to record your bit and say there is some good footage of you. Well done to both of you!!!

Take a look, Sat was directly overhead. These were the two with errors N 51° 38.097 E 000° 33.380 & N 51° 35.922 E 000° 33.941. This was one of the ones which was spot on N 51° 39.214 E 000° 32.529. Essex is pretty flat so there's not much difference in height. I was just trying to offer an explanation as to why I would trust my GPS over Google Earth. Interestingly, if you plot your second position in GE you can see that the aerial view is not directly overhead. About 150m to the west of the posiion is a pylon and you can see that the picture was taken from the SW of the pylon otherwise it would appear symmetrical from directly overhead (ignore the shadows). Given that the elevation here is only 30m or so the error caused by the perspective would only be minimal. An interesting idea would be for you to find a lighthouse on the Essex coast and obtain its position from the Admiralty Light Lists and check your GPS against that. Have a day at the seaside and try it every hour or so and see if/what error you get. You could also see how the lighthouse looks, positional wise, on GE.

I would always exercise caution when using Google Earth (GE) as the positions obtained from it can be many, many metres in error. The following may help to illustrate this. Start up GE and zoom into Canada Tower (51° 30.300'N, 000° 01.175'W) at an altitude of about 400m. I don't think that anyone will disagree that the (many) corners of the tower are at the same geographical position as the tower does not taper for most of its height. If you use the measuring tool in GE and measure a distance up one of the corners of the tower you will get a distance of about 40m. So, the corner of the tower is at the same geographical co-ordinates but a difference of about 40m exists. This is obviously down to perspective and can be seen becaue of the presence of the tower. What has now to be considered is which position is correct, that at the top of the corner or that at the bottom? Many months ago I asked Google about this but have not received a response. I assume, although could be totally wrong, that all the images shown in GE have co-ordinates adjusted to a zero metre height. In the case of Canada Tower that would indicate the co-ordinates near the base are more accurate. So, in a wide sweeping statement GE is more accurate at or very near to sea level. The point that I am trying to illustrate here is that in a hilly or mountainous area aerial shots are probably not directly over where a cache is hidden although it may look that way. If the Canada Tower affect is considered then the co-ordinates chosen could be well off. Canada Tower is only a couple of hundred metres high so by the time you get into the hills/mountains you could be looking at thousands of metres. If Canary Tower was 1000m high then the error between the top and bottom of a corner could be a couple of hundred metres. I hope that the above makes sense and would welcome any comments. Edited to add: The OP mentions setting six caches of which two were in "error". I assume there was little significance in height difference but is it possible, and it is hard to tell, if the caches fell in different aerial shot tiles?

I have just spent a little time trying to put together a cartridge and have a couple of questions about the Player. Am I correct in (1) assuming that the Player hunts out the GPS and that there is no way of telling the Player where to look for it and (2) there is no way, other than textual, of indicating where you are in the real world in relation to a Zone? To explain my question (2) a bit better... Can you display the geographical locations of zones on the PDA Player and see where you are in relation to them? I am sure I am missing something really elementary here!

Sounds very complicated!

Is there a list anywhere of the most found caches in the UK? One of mine has just gone through 500 and I wondered where it stood in the league. Obviously, it is about the numbers.

Well done guys. It won't please everyone but appears to be an acceptable solution to a very difficult problem.

If you are using a Sirf III GPS receiver ensure that "static navigation" is turned off. There are various utilities that can allow you to do this.

Slightly off-topic, but... I do not know how long you intend to stay in London and how much travelling you intend to do but I strongly suggest you consider getting Oyster cards as they can save you a lot of money. The link shows the fares for cash and for using the card. After getting the card(s) there is no more queuing at ticket offices. If you do not use all the money on the card(s) you can always give them to someone else who may be coming to London. It is also worth remembering that, although London is a big place, the tourist areas are not that far apart and it si quite often quicker to walk than use public transport.

I personally think that the forum moderators do a first class job considering that (a) they also have a private life ( review our caches in timely manner © probably do not have the luxury of using the "ignore" feature that I make copious use of and (d) must get bored witless with some of the drivel they have to read! Being impartial is extremely difficult and fence sitting as not as easy as some folks think it is. The problem would appear to arise when two moderators have a different opinion and fall on each side of the fence, as appeared to happen with the "Sun" posting yesterday. From my recollection one moderator posted, letting the thread continue, whilst another, obviously writing at almost the same time, closed it. Posters to the forums do not help the moderators by wandering off topic and I think it is in those threads that things tend to generally get a bit heated. Heated debate is good provided that it does not decline to personal attacks and insult swapping. I would tend to let the threads go until that level was reached. The (possibly) bigger issue in this case is "what are these forums for?" In the post that kicked this thread off the OP said it was off-topic so why post it on these forums? It then later appeared to transpire that the issue might have been on topic but the reason why was evaded by "those in the know". I look at the forums now and again to get a feel as to what is happening in the Geocaching world but do not mind using the "ignore" option to pass something that does not interest me. Finally, the other thing that occasionally happens on the forums, and could possibly embarrass the moderators, are postings that poll for opinions as to whether something may be allowed or not. If I have a query, I contact my local reviewer and let him know what I am planning. I always get a response in reasonable time and I always take his advise on board - simple! No confusion from several posters giving their often polarised views. When a private response from my local reviewer takes a day or two I know that he has entered into discussion with the other reviewers. As Lacto said in his opening post, they are chosen to do the job for their experience. Thanks guys - keep up the good work.

Not working for me either and I have the same versions as Dino.

You will also need: 1. Experience in removing or minimising the errors in the sextant 2. Nautical Almanac Data 3. Sight reduction tables 4. Nories Tables (or equivalent) if you are not going to use sight reduction tables 5. A highly accurate watch chronometer 6. A mercury bath to create an artificial horizon 7. Knowledge of navigation for using a sextant. I suppose that there is software available today that does away with items 2 to 4. The last time I used a sextant was just as GPS was being introduced to Merchant ships and was prior to 1984. The tables, formulae, etc that I used to use were not based on WGS84 but on the assumption that the earth was a sphere. Can anyone tell me if the formulae that is used today, for celestial navigation, is for WGS84 and point me towards it? Did sextant development stop with the readily available GPS system?

Why not have the event the week after "The Great Yorkshire Show" (8th-10th July) and make it a CITO event as well. You never know, the GYS organisers may offer incentives to help with the clean-up. Is there such a thing as a Mega CITO event?

For something that is not the norm - such as this suggestion I would have thought that mooting it with the revieweres would have got you an answer! If I remember correctly, when a cache is submitted for review you have to place a check mark in the submission saying that the "listing" is active. If you do not check the box the reviewers do not see it. If the "listing" and "cache" being active are one and the same only a reviewer can say.

Through a bit of detective work I have tracked down Michael Bradshaw, who is not a cacher, and have returned his possessions to him. He had stopped at The Winchester Geese cache to read the ribbons on the gates. Please lock this thread.

Thanks for the suggestion but I have tried that without success.

Whilst caching, today, I found something belonging to a Michael Bradshaw. As it was less than a metre from the cache I am hoping that he is a cacher. The cache in question was "The Winchester Geese" in south London and I think Michael may live in north London. Thanks.

Away from the math and back on topic... My hot tip from today. I use a bluetooth GPSr with a PDA and the GPSr fits in a pouch on one of the straps on my rucksack. Cardinal sin - don't take your rucksack off and wander around with just the PDA!!! Plonker of the century or what?

I assume you have not tried this one

My maths teacher taught us "Some Officers Have Carts And Horses To Order About" to remember this one - still can remember 40 years later but I do use it most days! For those to whom this means nothing: Sine = Opposite/Hypotenuse Cosine = Adjacent/Hypotenuse Tangent = Opposite/Adjacent I'm struggling now to see how this is a tip or trick but a couple of my caches require this knowledge!

I think that that is precisely what the problem was that sparked the end of virtuals. In the USA some virtuals were set up every 500 feet in a parking lot to make power trails, or else they were as mundane as log a lampost . Rumor has it that it was a certain virtual set at the site of a discarded beer can that was the final straw for our Lords and Masters (sic). I have mixed feelings about 'Off yer trolleys'. The don't have to be bad, but it does seem harder to place a quality cache given such a dull location. My own attitude is do them if I am passing, and they are certainly good caches for me to do when I am in a suit and have this strong need to do at least one cache when I am working away from home in a new area, and don't neccesarily want to go clumping about in the mud. Some of the ones I have found are quite ingeniously hidden and others, alas, are just bunged in with no imagination. I have done 8 out of the available 45, so I would not like to form any sort of meaningful stats out my experiences. The first one I ever found was on the top of my list of the worst caches I have ever done for a while (until the dog poo micro bin took top slot). I think it is now archived. It was in a leaky breath strip container and the log was stinky and mouldy. The cache owner had lobbed it out on a whim and then left the area, never to return. It was stuck to a trolley collection shelter in a huge supermarket carpark. Did I enjoy it? No... Was I pleased to get one smiley in an otherwise cache free desert? Yes! I don't think any of the problems described are unique to 'off yer trolleys' or even to micros in general. Don't get me wrong - I like micros. I live in London so am used to them and even have some of my own! The problem here is probably of my own making - I did not look at the map before going there. I knew I would be in the area so just loaded them along with the other, thankfully, better caches. Unfortunately, my experience of the ones I came across yesterday has probably biased me against the whole "trolley" series and I will probably avoid them in the future. This is unfair to those setters who may have given their trolley caches some thought and made the cache a worthwhile find. Your comments about being suited and booted as opposed to jungle rigged are valid points though.

This is a double edged problem in that old f***s like myself automatically use BODMAS whereas younger folks probably work from left to right. When I see caches using brackets, etc I usually contact the cache owner to determine which method has been used as the difference can be large. I think Bambography has a good point here in that a checksum should be included. Geochecker is also a good resource but not much use when you are in the cache vicinity and you do not have access, by any means, to it.

I always though the "O" in BODMAS stood for order as in 2^4 (2 to the power 4), for example, would follow the brackets, then would come division, etc.

I came across two micros in Kent, yesterday, in the "trolley" series. I think these reflect all that is bad about micros and would never have foreseen anyone placing a virtual in a supermarket car park. I did not even bother looking for them and would have rather spent my time at home googling, for anything, than waste time looking for these. All the virtuals I have done, to date, were in interesting places or purveyed interesting information.