cap 'n chris said: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!
biffa said:Also worth looking at is:
http://www.ietodd.co.uk/clino/
Horace said: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.
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:Les W said: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)
Peter Burgess said: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:
beardedboy said: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.