Measuring cave depth

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Measuring cave depth

Postby deepcave1 » Jul 19, 2010 8:08 pm

hey guys,
i know this post doesnt really belong on this thread, but i am looking for some help. what is the best way to accurately measure your depth from the cave mouth? thanks in advance of any help you may could give me!
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Re: Measuring cave depth

Postby Jeff Bartlett » Jul 21, 2010 10:27 am

deepcave1 wrote:hey guys,
i know this post doesnt really belong on this thread, but i am looking for some help. what is the best way to accurately measure your depth from the cave mouth? thanks in advance of any help you may could give me!


Survey the cave with compass, tape and clinometer. Enter into a cave survey program like Walls or Compass to derive the vertical extent.
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Re: Measuring cave depth

Postby Phil Winkler » Jul 21, 2010 2:41 pm

Or, survey as Jeff says and use trigonometry to determine the vertical extent of each measured angle shot. The sum of the vertical extents of each angle = the total depth of the cave. Keep in mind that some shots may go back up, too.
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Re: Measuring cave depth

Postby Scott McCrea » Jul 21, 2010 2:52 pm

Survey is the most accurate way. And, every cave deserves to be surveyed. But, for a quick and dirty depth, try an altimeter.
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Re: Measuring cave depth

Postby Jeff Bartlett » Jul 21, 2010 3:10 pm

Phil Winkler wrote:Or, survey as Jeff says and use trigonometry to determine the vertical extent of each measured angle shot. The sum of the vertical extents of each angle = the total depth of the cave. Keep in mind that some shots may go back up, too.


This is going to come across as incendiary, and it's not intended as such, but... why even bother suggesting that? If the poster is computer-savvy enough to post on a message board, then I assume he or she is savvy enough to learn free software like the cave survey programs we mentioned. What's the point of working up the trig, by hand, instead? Dude just wants to know how deep the cave is, and we're dropping a T-word on him?

Sometimes I feel like we offer 3 or 4 solutions to inquisitive new posters, as a matter of course, when they might be better-served for us to say "here is what's generally accepted as the best/easiest" way and proceeded to helping them down that path if necessary.
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Re: Measuring cave depth

Postby Phil Winkler » Jul 21, 2010 3:13 pm

I like the altimeter suggestion best. :rofl:
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Re: Measuring cave depth

Postby NZcaver » Jul 21, 2010 4:30 pm

Phil Winkler wrote:I like the altimeter suggestion best. :rofl:

Me too. :kewl:

Jeff Bartlett wrote:Sometimes I feel like we offer 3 or 4 solutions to inquisitive new posters, as a matter of course, when they might be better-served for us to say "here is what's generally accepted as the best/easiest" way and proceeded to helping them down that path if necessary.

Like with vertical systems? :shrug:
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Re: Measuring cave depth

Postby Jeff Bartlett » Jul 22, 2010 8:43 am

NZcaver wrote:
Jeff Bartlett wrote:Sometimes I feel like we offer 3 or 4 solutions to inquisitive new posters, as a matter of course, when they might be better-served for us to say "here is what's generally accepted as the best/easiest" way and proceeded to helping them down that path if necessary.

Like with vertical systems? :shrug:

Yep, those threads seem to always degenerate into "or you could do THIS or THIS" responses that do nothing to answer the original question. Phil, I didn't mean this as an attack or anything, I've done exactly the same thing on more than one occasion, I kinda felt bad after posting. I dunno, I try to think of how our cavechat posts are going to remain google-able on an essentially permanent basis and there will never be a shortage of new cavers looking to the board for advice. The original poster asked for the best way to accurately measure cave depth; does anyone on this board actually disagree that the best-practice is a proper survey used in conjunction with modern software?
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Re: Measuring cave depth

Postby Phil Winkler » Jul 22, 2010 8:56 am

Jeff, no offense taken. However, IMO, saying what is best is simply the speaker's/writer's opinion. Ultimately, the accuracy of the survey determines the depth. Rarely is anyone else going to do a re-survey to check the accuracy. I just think that doing the math manually is important to understand how the computer does it automagically. I've never used either of those programs, but haven't surveyed in years either. The last cave I surveyed was probably Scott's Cave in Madison Co, AL in the early 80's.
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Re: Measuring cave depth

Postby George Dasher » Jul 23, 2010 7:53 am

Altimeters measure air pressure, which is not the same as elevation in a blowing cave.
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Re: Measuring cave depth

Postby trogman » Jul 23, 2010 9:12 am

Everyone has their own preferred method. I get all my survey data, and then plug the numbers into AutoCAD as a line plot. Then I simply check the Y axis distance from the highest to the lowest point, and that gives me my vertical extent. I have used one of those cave mapping programs once or twice, but it just didn't work good for me. Maybe if I worked with it more, I would grow to like it, but sometimes us older folks ( :yikes: , am I really one of those now?) get set in our ways, and continue to use what has always worked for us despite someone coming up with an "easier" method.

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Re: Measuring cave depth

Postby Dwight Livingston » Jul 23, 2010 2:13 pm

And if all you want is depth, you don't need a compass and your plot can be flat, like on graph paper with a protractor. Of course, seems a waste of time if you don't get a full survey.
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Re: Measuring cave depth

Postby gdstorrick » Jul 24, 2010 8:13 am

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Re: Measuring cave depth

Postby gdstorrick » Jul 24, 2010 8:20 am

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Re: Measuring cave depth

Postby Anonymous_Coward » Jul 26, 2010 9:52 am

George Dasher wrote:Altimeters measure air pressure, which is not the same as elevation in a blowing cave.


Air pressure is not the same thing as elevation on the surface either, but it's pretty damn close. That's why altimeters are used to determine elevation above ground all the time. It works exactly the same way underground.

Pressure is always changing, be you above or below the surface. With calibration, an altimeter can a nice tool for learning about caves.
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