jlillest wrote:Chads93GT wrote:Well.............when you survey downstream and end up with an uphill gradient because you didn't do backsites........ would you call that a quality survey? lol
Chad, thanks for the rude comment.
I'm not sure that you understood the scenario, but I'd like to hear you explain in greater detail how backsights would have helped me. Backsights may have helped with any singular instrument reading errors, but the error we discovered was solved by calibrating the instrument (yeah, should've done this when I got it, I know). This recurring error would have been present had we been using backsights or not. Fortunately, this particular error is easily solved after the survey is done. Were there other errors? I don't know, but I'd be happy to show you to the cave if you want to show me up.
Now, for a serious discussion, do you guys who use backsights with two sets of instruments account for your instrument errors when you force a two degree agreement between fs/bs? So, imagine that you have one clino at -2 and another at +1, that's three degrees difference when the instrument readers read the correct shot. If you're not accounting for this in your agreement, then there's a potential that your frustrated instrument readers are going to massage the numbers make it work. Seem far-fetched? I've seen it happen, on several trips.
All-in-all the difference between the ways we survey is minimal and both ways have their merits. Tools in the toolbox, as it were.
More importantly, though, I think next time I have a quick question about survey stuff I'll just go buy a copy of Dasher's cave survey book that I lost years ago. Or, just email George personally.
-Jon
Rude, maybe, but you are the one calling us dogmatic for using backsites to check our surveys for accuracy, yet at the same time you are inquiring about why your downstream survey came out uphill...... I call it how I see it. A spade is a spade, if that makes me an ass, then Im an ass. Doesn't bother me one bit. You make it sound as if we are silly for doing backsites on our surveys.
When doing a survey with multiple sets of instruments, we check them all before hand as to how accurate they are towards each other. We keep it in the notes and make corrections accordingly. WE also initial the notes as to who is making which shots, and of course we even write down our compass serial numbers so there is no confusion down the road.
Checking the clino for accuracy before you started would obviously have helped, but if its THAT far off, I think I would be sending it back to the manufacturer to have it recalibrated, rather than having an inaccurate piece of equipment.
Sorry you don't like some of the answers that you have recieved on here, but when you get standoffish about doing backksites , then give off the impression that we are silly for doing backsites as it slows the survey down and we obviously sketch slow, dont be suprised if some of us dont warm up to you.
we all use different methods, some work better than others. When I see discussions about survey I pay attention. I like to find ways to make my job easier, but I will not sacrifice effeciency for speed. I was taught to do a thorough survey and not a half ass survey by guys who are cartographers on the largest cave project in the world. Ive seen enough maps done from "back in the day" in my area. God forbid that the maps I have a part in ever look like some of those maps.
here is a tidbit on why I am anal retentive when it comes to accuracy. One of the largest caves in the state of missouri had a radio location project done a couple years ago. One of the areas they were trying to locate was around 500 feet off as to where it was supposed to be on the surface. Accuracy.........its a good thing.
do I always do back sites? Nope, if a passage is horrible crawl and dead end, generally no backsites, i simply maike the guy who is setting stations by backing up all the way in the narrow crawlway as its too small to turn around in, we tend to simply do "backsites" no front sites and he double checks the back sites. It just depends on how grim the passage is.
As I said, sorry if I come off as an ass, but calling us dogmatic for doing backsites sort of hit a nerve. My apologies.