Author Topic: Shetland Attack Pony  (Read 17327 times)

Offline Bob Smith

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Shetland Attack Pony
« on: September 25, 2007, 10:54:20 am »
Does anyone have any Info on where i can find details about the Shetland Attack Pony surveying device?

Offline Peter Burgess

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Re: Shetland Attack Pony
« Reply #1 on: September 25, 2007, 10:58:05 am »

Offline Bob Smith

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Re: Shetland Attack Pony
« Reply #2 on: September 25, 2007, 11:04:14 am »
You are a star, googled this and nothing came up, thanks

Offline biffa

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Re: Shetland Attack Pony
« Reply #3 on: October 02, 2007, 04:32:33 pm »
Also worth looking at is:
http://www.ietodd.co.uk/clino/

Offline AndyF

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Re: Shetland Attack Pony
« Reply #4 on: October 02, 2007, 06:18:53 pm »
Shetland Attack Pony; LOL Great name...

I hope this project does well, it just looks like a great idea.... I'd probably buy one if I ever had anything to survey!!
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Offline Cap'n Chris

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Re: Shetland Attack Pony
« Reply #5 on: October 02, 2007, 06:48:37 pm »
Biffa's link leads to the fabled and dizzying land of Ubergeekdom. I visited it for a while but my eyes glazed over and my brain squealed while becoming gently frazzled.

I'm back in good old Numptyland now. Phew! 

darkplaces

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Re: Shetland Attack Pony
« Reply #6 on: October 02, 2007, 11:34:50 pm »
How can I get one and do they eat much grass?

Offline biffa

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Re: Shetland Attack Pony
« Reply #7 on: October 03, 2007, 11:40:04 am »
Biffa's link leads to the fabled and dizzying land of Ubergeekdom. I visited it for a while but my eyes glazed over and my brain squealed while becoming gently frazzled.

I'm back in good old Numptyland now. Phew! 


Geeks rule.  Ha ha I squealed his brain.

Offline beardedboy

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Re: Shetland Attack Pony
« Reply #8 on: October 03, 2007, 02:12:03 pm »
Also worth looking at is:
http://www.ietodd.co.uk/clino/

This unit looks quite a bit larger than the SAP, and only does clino readings, unlike the SAP, which does compass and clino.

However, it does look like you could knock one together yourself if you are sufficiently geekyfied, but it would prbably still cost about £70? once you had got the board built up etc. A bit cheaper than a Sunto clino.

The SAP is £250 but does seem to have some obvious advantages over traditional compass clino combinations, which only cost a little less.
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Offline menacer

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Re: Shetland Attack Pony
« Reply #9 on: October 03, 2007, 06:21:02 pm »
Has any one done any comparisons with for example the suunto tandem.
I have heard that the sap used against a tandem on an experiment run by only 1 person, had a larger error margin than the Tandem.(5 degrees to 2 i think)
I appreciate this was only one comment/experiment, has anyone out there done the 2 side by side for comparison.
Im not after a "its crap or its Ace " comments just real experiences...my tandem ...the compass bit has just packed up (sticks)after 2 good years... so im looking at replacing it...
thanks
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Offline Horace

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Re: Shetland Attack Pony
« Reply #10 on: October 04, 2007, 11:57:46 am »
I was involved in the initial comparison of the SAP against the suunto tandem where we surveyed the round trip in Bull Pot of Witches. 2 sets of readings were taken with the suunto instruments, one by an experienced surveyor and one inexperienced (myself), and one set taken with the SAP by another inexperienced surveyor. We used a disto to record one distance reading for all data sets. The error in the loop closure with the SAP was 1.08% compared to 1.8 and 2.7% for the two suunto readings.

A fuller description of this is in Compass Points 37 http://www.chaos.org.uk/survex/cp/CP37/CP37.pdf

I've not heard of the experiment you mention, but I suppose more comparisons have been made since there are 6 or 8 in use now. I think Langthwaite Pot on this forum might be able to give some more feedback on using it in a harsher cave environment than BPotW.

Offline Les W

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Re: Shetland Attack Pony
« Reply #11 on: October 04, 2007, 06:22:40 pm »
I believe the SAP was used at the surveying competition at HE this year. It didn't win though as Peter Burgess felt the need to show of with his conventional set of instruments (0.2% ish, I think (I'm sure he will put me right) misclosure error)  :thumbsup:
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Langthwaite Pot

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Re: Shetland Attack Pony
« Reply #12 on: October 04, 2007, 08:10:15 pm »
I've not heard of the experiment you mention, but I suppose more comparisons have been made since there are 6 or 8 in use now. I think Langthwaite Pot on this forum might be able to give some more feedback on using it in a harsher cave environment than BPotW.

Yep, you should probably take what I'm about to say with a pinch of salt because I'm a relatively inexperienced surveyor, but we used both an SAP and a Suunto Tandem to survey 'The Dark Side of The Grind' in Easegill this Summer. The passages are in general a surveyor's nightmare due to being small (often body sized), bendy, wet and very, very muddy!. Although unfortunately we didn't do any loops, in terms of ease of use (which I suspect strongly corresponds to accuracy in this sort of passage) the SAP was far superior. Not having to sight from the station was the major advantage, although the SAP was also easier to keep clear of mud. We did still have a problem with the lense clarting up, but I think Phil's working on that.

The SAP's were also used a lot on the CUCC expo to Austria this Summer, and again they were the tool of choice for most people (again, apparently due to their ease of use over traditional instruments)

George.




Offline Peter Burgess

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Re: Shetland Attack Pony
« Reply #13 on: October 04, 2007, 08:25:01 pm »
I believe the SAP was used at the surveying competition at HE this year. It didn't win though as Peter Burgess felt the need to show of with his conventional set of instruments (0.2% ish, I think (I'm sure he will put me right) misclosure error)  :thumbsup:
Graham C. and I did the loop twice, each taking our turn with the instruments. By far the greatest factor affecting accuracy was the presence of large amounts of steel at various points around the loop. This factor, regardless of the instruments used, would have been the greatest source of potential inaccuracy. Graham achieved 0.25%, and I achieved 0.5% Maybe, had we used a SAP, we could have got it even tighter. There was another factor that also helped, but if I told you what it was, someone else might win next year, so it's staying a secret.  :tease:

Offline Cookie

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Re: Shetland Attack Pony
« Reply #14 on: October 05, 2007, 09:58:21 am »
There was another factor that also helped, but if I told you what it was, someone else might win next year, so it's staying a secret.  :tease:

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Offline Peter Burgess

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Re: Shetland Attack Pony
« Reply #15 on: October 05, 2007, 10:02:53 am »
Nope. That's standard practice.

Offline beardedboy

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Re: Shetland Attack Pony
« Reply #16 on: October 05, 2007, 10:27:05 am »
Yeah, the SAP came 2nd in the Hidden Earth surveying comp, with a closure of just over 2%. The major problem with using the SAP for that course is that it was very bright sunlight, so it was near impossible to see the laser dot. This is obviously not a problem inside a cave, or with the appropriate above ground kit (some sexy red glasses and a bit of 3M reflective tape) which we obviously didn't have!

The small advantage that we did have is that if there was a bit of metal in a preferred survey point you can just put a but of string between the survey point and the 'eye' on the rear of the SAP, then pull the SAP so the string is tight and you will still get an accurate reading because the SAP is still in the correct line.

Also a problem with these very purdy LED lights that are becoming more popular (Scurion, Stenlight, Nova, etc) is that they all use magnetic switches. With the SAP you can keep the device away from your head and the magnet and therefore keep accurate readings. Last time I talked to Phil he was also talking about the possibility of making the SAP beep when it detected a large change in magnetic field, but this isn't confirmed yet.
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Offline Peter Burgess

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Re: Shetland Attack Pony
« Reply #17 on: October 05, 2007, 10:41:57 am »
Yeah, the SAP came 2nd in the Hidden Earth surveying comp, with a closure of just over 2%. The major problem with using the SAP for that course is that it was very bright sunlight, so it was near impossible to see the laser dot. This is obviously not a problem inside a cave, or with the appropriate above ground kit (some sexy red glasses and a bit of 3M reflective tape) which we obviously didn't have!

The small advantage that we did have is that if there was a bit of metal in a preferred survey point you can just put a but of string between the survey point and the 'eye' on the rear of the SAP, then pull the SAP so the string is tight and you will still get an accurate reading because the SAP is still in the correct line.

Also a problem with these very purdy LED lights that are becoming more popular (Scurion, Stenlight, Nova, etc) is that they all use magnetic switches. With the SAP you can keep the device away from your head and the magnet and therefore keep accurate readings. Last time I talked to Phil he was also talking about the possibility of making the SAP beep when it detected a large change in magnetic field, but this isn't confirmed yet.

But would have been third if Graham and I had insisted on entering both our efforts to the competition!  :tease: At several points around the competition loop we did not take the bearing from the survey point, but from a point in line, either behind or in front of it (which I think is what you are describing). This is just as simple with a Suunto as it is with a SAP.

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Re: Shetland Attack Pony
« Reply #18 on: October 05, 2007, 01:16:17 pm »
I used the SAP this year in Austria. As already pointed out, a big advantage is that you don't have to put your head near any survey stations in order to sight. Another really big advantage is that (at last!) you can get an accurate compass reading on a steeply sloping survey leg. This saves loads of hassle and will surely give better results in many cases.

One thing I found hard, especially with very long survey legs, is that even a slight wobble of the instrument makes the dot dance about. Obviously all that is happening is that you are "seeing" the innacuracy which can result from not pointing the instrument steadily. I'm sure the same applies with conventional instruments, but it's kind of disconcerting to see the dot wobble about and I actually found it quite tiring on my eyes. Something to think about is that at long range a larger target is needed than someone's finger - get the person you are sighting to to hold up somthing a bit bigger (their hand held flat for example).

Mark

Offline Peter Burgess

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Re: Shetland Attack Pony
« Reply #19 on: October 05, 2007, 01:24:26 pm »
A useful exercise to evaluate the SAP might be to have the same team survey a loop once with a SAP and once with Suunto (other brands are available) compass/clino, using identical survey points. Perhaps it's been done already. Actually, I expect it has.

Dave H

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Re: Shetland Attack Pony
« Reply #20 on: October 05, 2007, 01:53:38 pm »
Biffa's link leads to the fabled and dizzying land of Ubergeekdom. I visited it for a while but my eyes glazed over and my brain squealed while becoming gently frazzled.

I'm back in good old Numptyland now. Phew! 


Geeks rule.  Ha ha I squealed his brain.

I designed and built an electronic compass, yaw, roll and pitch sensor head using PICs and similar sensors (and a few more) around 1998/9 which fed into a sophisticated micro that actually crunched the numbers (which I didn't program). The application was for light aircraft and we only had to achieve an accuracy, resolution and repeatability of 1 degree in each axis. Accuracy and resolution were not a problem, but the repeatability over a wide range of conditions was the killer.
I would certainly say stick with measuring one plane of movement (such as the linked device) for an easier life! Having said that we did achieve the spec. with quite a bit to spare, but it really was prohibitively expensive for applications such as surveying (I think that the aircraft kit was being sold for $5000)  :o
If I ever had the time  :down: I'm sure that I could do something cheaper now, but I would want 0.5 degree specs. and for it to have a distance measuring laser pointer.

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Martin Melzer

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Re: Shetland Attack Pony
« Reply #21 on: October 13, 2007, 07:47:58 pm »

Also a problem with these very purdy LED lights that are becoming more popular (Scurion, Stenlight, Nova, etc) is that they all use magnetic switches. With the SAP you can keep the device away from your head and the magnet and therefore keep accurate readings. Last time I talked to Phil he was also talking about the possibility of making the SAP beep when it detected a large change in magnetic field, but this isn't confirmed yet.

Scurion does not use a magnetic switch!
I have developed a compass/clino module myself (see my Auriga project - http://www.melzer.ch/html/aurigaimport.html) and I know how important it is to have no magnetic parts nearby.
For Scurion, we ran a finite element magnetic field simulation and found out, that using currently available magnetic field sensors, it is not possible to use magnets that are weak enough in order not to disturb the compass (I used a limit of 1% field disturbance in 10 cm distance). For that reason, we have the reletively complicated mechanical solution. Few swiss cavers would have bought the lamp if they would know that it ruins their surveying accuracy.

- martin

Offline menacer

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Re: Shetland Attack Pony
« Reply #22 on: December 22, 2007, 09:01:59 am »
Borrowed one the other day for a little Mendip project i'd been promising to do for some time.Also had a disto.
It was a pleasure not to have to contort myself into funny position just to take a reading. Also there was no extra faffing with lighting the instrument just to take a reading.
Another good point, you can train it ahead to the area of the next survey station and see if youve got a good line of sight. (If you can see the red dot, you have)
Best of all, it is possibile to survey solo.
If one of the people surveying, cant fit through the squeeze or get up a climb the other can continue alone....
The downside of that is, Ive got no excuse to not return to all the bits of cave ive travelled alone, and remain unsurveyed....
Back to Draenan for this girlie....phhh

If anyone knows Phil and reads this, can you let him know I cant get the program to run in vista.(even with xp compatibility mode)
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Offline Chris J

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Re: Shetland Attack Pony
« Reply #23 on: January 02, 2008, 02:24:21 pm »
Surveying Solo... obviously need a disto as no one to hold the tape measure - but a good advantage to this.

Offline Cave_Troll

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Re: Shetland Attack Pony
« Reply #24 on: January 02, 2008, 04:30:21 pm »
As long as you have a good base line, you can conduct a survey using just mag and dec, working in triangles, and then work out the distances using 3d trig.