Surveying tiny passage

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Surveying tiny passage

Postby GroundquestMSA » May 9, 2013 8:29 am

I've already asked for tips on wet and muddy passage, now for tiny. My upcoming survey is a resurvey of a cave currently listed at 688 feet. Years ago, before I knew there was such a thing as cave maps, I pushed a small passage far beyond what I now know is the "too tight" stopping point on the current map. Since then, we have confirmed a connection to a nearby sinkhole that we are waiting to unsump so that we can survey all the way through.

There are approx. 500 feet of unsurveyed passage that is too small to turn around in. The first 100' is 1' - 1.5' wide and 1.5' -2' tall and the rest is 2' - 3' wide and 1' -1.5' tall. The passage has bedrock floor for the first hundred, and sand and cobbles for the rest.

The survey will be a two person effort, and I'm looking for advice on how to divide the responsibilities, and how to set stations. I don't think it's realistic to expect the lead man to back through this entire section of cave. There are many difficult squeezes that may be impossible to negotiate in such an awkward fashion.

Here's what I'm thinking. Lead man carries the book and a stick of chalk or some other marking device. As he crawls, he marks the stations with chalk and then continues past the station until his feet are even with the mark. The instrument man stops at each mark and shoots the lead's boot sole with the laser, then takes azimuths to the center of the passage. In each case it would be assumed that the station is floating in the center of the passage. This would allow passage dimensions to be taken as two measurements (width and height) instead of four (lrud).

Obviously this method would sacrifice some accuracy. Do you think that's acceptable given the conditions? Is there another way to survey this kind of junk that would allow for better accuracy while still maintaining some sort of efficiency?

Thanks!
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Re: Surveying tiny passage

Postby rjack » May 9, 2013 1:41 pm

You might consider using flagging tape and removing it when you're done instead of marking the walls with chalk. I have never heard of shooting azimuths to a "floating point" in the center of a passage? I would maximize the shot length by zig zagging the stations from left to right wall. Then record passage height and width-left or width-right for each station.
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Re: Surveying tiny passage

Postby ian mckenzie » May 9, 2013 1:47 pm

Interesting. I wonder if the point man could have no function other than to crawl forward until you yell 'stop'. Then you could use his boot as the station, measure and record everything including distance with an EDF shot to his sole, then crawl forward to his boot and note the station location yourself. Could perhaps use a standard tape rather than an EDF, tied to point's ankle and subtract the number of centimetres shown where the tape 'exits' the station (i.e. perhaps 15cm will be used in the ankle tie-off); you have the reel end yourself and let out or reel in as required (i.e. you do everything except the point crawling). In lieu of duplicate backsights you could repeat the whole survey on the way out, if you were so inclined.

I suppose the point-crawler could do Book to speed things up.
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Re: Surveying tiny passage

Postby ian mckenzie » May 9, 2013 1:53 pm

rjack wrote:I have never heard of shooting azimuths to a "floating point" in the center of a passage

This used to be common practice in our cave surveys here in the Cdn Rockies - Instrument's eye to Point's light, helps if Instruments is taller than Point. Floating stations technique is presently used only for difficult conditions where wall stations are impractical.
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Re: Surveying tiny passage

Postby rjack » May 9, 2013 3:04 pm

ian mckenzie wrote:Interesting. I wonder if the point man could have no function other than to crawl forward until you yell 'stop'. Then you could use his boot as the station, measure and record everything including distance with an EDF shot to his sole, then crawl forward to his boot and note the station location yourself.


Rather ingenious since it maximizes the shot length to far as the second person can see. Although you might actually want a few more cross sections in a twisty passage. With an EDF and shooting azimuths to the boot, the survey itself is going to be alot faster than the waiting required to let the second catch up to the first to note the actual station/boot location.

ian mckenzie wrote:
rjack wrote:I have never heard of shooting azimuths to a "floating point" in the center of a passage

This used to be common practice in our cave surveys here in the Cdn Rockies - Instrument's eye to Point's light, helps if Instruments is taller than Point. Floating stations technique is presently used only for difficult conditions where wall stations are impractical.


Thanks, as mostly a cave diver this isn't something I have much opportunity to do.
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Re: Surveying tiny passage

Postby GroundquestMSA » May 9, 2013 3:37 pm

ian mckenzie wrote:I suppose the point-crawler could do Book to speed things up.


That's the plan. Crawling up to the boot instead of making a mark is a good idea. I'm now trying to come up with ways to eliminate the idle sitting this plan may introduce. How about this: 1.Point crawls into position 2.Instrument shoots azimuth, distance, and dimension, which are recorded by point 3. As instrument crawls to boot, point sketches the passage ahead (lot's of short shots and featureless passage make this possible) 4. Instrument reaches boot, and as point crawls to next station, instrument measures dimension and draws x-section. Point carries 5x7 book, instrument carries laser, tandem, and 3x5 book.

The only downside I can see is the need for two books, but that doesn't scare me too much since the cave is mostly dry. It also allows for some flexibility if the timing doesn't work out right. Instrument could let point draw the x-sections or point could let instrument write down measurements.
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Re: Surveying tiny passage

Postby chac » May 9, 2013 4:29 pm

Ian brings up some good suggestions. I've used this basic methodology many times when surveying/taping underwater caves in Quintana Roo using a 2-person team. If you can maintain verbal communication, that's even better. We used a prearranged code of "tugs" on the tape. Point person looks for the optimal station position, 2 sharp tugs from Point means I am on station. They have the dumb end of the tape and hold it steady on station. Book person takes all the survey data, two tugs back to Point means "move forward, Book has all the data".

Don't reel up the tape at each station. In this case you can drag the tape through the passage as the team progresses. Book can apply a steady pull restraining the tape (and Point) from froward progression when they are busy drawing. A steady pull means stop. After the stop, two tugs from Book means move forward. A simple set of whistle blasts will work as well if you won't be using a tape for physical communication.

A chicken loop can be used to attach the tape to Point's boot. Chalk is a form of limestone as you know. If you do make chalk marks, make sure you try to be consistent where Point places the mark on the passage (L,R,U). Wet chalk gets a little greasy. If shooting a laser, you can get a good reading from the back of Point's helmet. Attach a square piece of plastic to the back of Point's helmet (maybe just a strip of white duct tape?).

It would be great if you could get out at the sink that is at the end of the traverse! :banana_yay:
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Re: Surveying tiny passage

Postby ian mckenzie » May 10, 2013 10:00 am

GroundquestMSA wrote:The only downside I can see is the need for two books, but that doesn't scare me too much since the cave is mostly dry. It also allows for some flexibility if the timing doesn't work out right. Instrument could let point draw the x-sections or point could let instrument write down measurements.

I don't see why Point can't do all of the book functions, sketching XCs ahead up to the next proposed station while waiting for Instruments to read the previous leg.

You will no doubt discover refinements to any technique when you are actually in the crawl.
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Re: Surveying tiny passage

Postby GroundquestMSA » May 10, 2013 2:26 pm

ian mckenzie wrote:I don't see why Point can't do all of the book functions, sketching XCs ahead up to the next proposed station while waiting for Instruments to read the previous leg.

You will no doubt discover refinements to any technique when you are actually in the crawl.


Yep. We'll see what happens. I'm just trying to give instrument something to do while point is crawling. While waiting for drought, we will get to practice this technique on a horribly little VA loop I've been putting off.
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Re: Surveying tiny passage

Postby Extremeophile » May 10, 2013 2:43 pm

I would contribute to this thread, but everything seems to have been covered, and I'm more of a borehole specialist anyway. I guess someone needs to survey the passages where it's too small to turn around, but I have more experience with issues like not being able to see the walls or ceiling, and dealing with distance readings that are beyond the capability of my Disto. It's also tough when the instrument person is yelling the readings as loud as they can but the book person still can't hear. If anyone encounters these sorts of issues be sure to give me a call ... I'm in the members manual.
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Re: Surveying tiny passage

Postby GroundquestMSA » May 10, 2013 3:10 pm

Extremeophile wrote:I would contribute to this thread, but everything seems to have been covered, and I'm more of a borehole specialist anyway. I guess someone needs to survey the passages where it's too small to turn around, but I have more experience with issues like not being able to see the walls or ceiling, and dealing with distance readings that are beyond the capability of my Disto. It's also tough when the instrument person is yelling the readings as loud as they can but the book person still can't hear. If anyone encounters these sorts of issues be sure to give me a call ... I'm in the members manual.


I actually had a distance reading below the capability of my Disto recently, but thanks so much, I'll keep that in mind.

Actually, same VA cave that has the bitty loop that I mention above has presented me with one such problem. After all of that boasting, you had better give me an exhaustive and definitive discourse on the various methods used to overcome this obstacle. In the lower level of this cave, the passage grows to a respectable size (perhaps not large enough to accomodate your glorious reputation, but I found it quite big :big grin: ) and has many high domes. The tallest of these has been disgorging a considerable shower every time we've visited. Our attempts to measure the full height of the dome have failed, possibly because the rangefinder is inadequate, but probably because the water droplets obscure the target. Our best measurement to a ledge outside of the spray has been 116'. What would you do? Complex mathematics? A bolt climb? Perhaps you carry a lamp capable of evaporating the stream long enough to get a clear shot? Or a bow and suction cup arrow with tape attached?
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Re: Surveying tiny passage

Postby Extremeophile » May 10, 2013 3:46 pm

GroundquestMSA wrote:What would you do? Complex mathematics? A bolt climb?
You're probably correct that water droplets are scattering the Disto laser and preventing a reading. Even if you got an accurate measurement of the ceiling and it was 150-200', you'd almost certainly wonder if there wasn't another passage up there. Sometimes you just have to follow where the cave leads. I see a bolt climb in the future. If you're sure there are no leads, and just want a measurement, perhaps the helium balloon method is an option.

Perhaps you carry a lamp capable of evaporating the stream long enough to get a clear shot?

Actually, I do.
http://www.scurion.ch/jm/index.php?Itemid=109

Although I must admit that in particularly wet domes using a high lumen light doesn't always help. It's like turning on your car's high beam in a snow storm.
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Re: Surveying tiny passage

Postby GroundquestMSA » May 10, 2013 4:02 pm

Extremeophile wrote: Even if you got an accurate measurement of the ceiling and it was 150-200', you'd almost certainly wonder if there wasn't another passage up there. Sometimes you just have to follow where the cave leads. I see a bolt climb in the future.


I've been wondering what's up there for about a year now. I'm not qualified to perform a bolt climb, maybe someday.
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Re: Surveying tiny passage

Postby Scott McCrea » May 10, 2013 4:37 pm

What VA county are you in? I can help with dome climbing or at least hook up with cavers that can.
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Re: Surveying tiny passage

Postby firemedic1015 » May 10, 2013 6:18 pm

VA bolt climb? I'm in! When do you want to do it.
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