Ask Cavers: What are Your Best Survey Tips & Tricks?

February 6, 2013
Caver surveying in Arizona's KyPet Caverns.

Caver surveying in Arizona’s KyPet Caverns. Photo by David A. Riggs/flickr

Although surveying caves can be exciting, sometimes it can also be a slow, cold and miserable experience.

This week we want to hear your best tips and tricks to make the survey process more efficient, more accurate, and especially more enjoyable.

Share your comments and suggestions in the discussion below.

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Comments (6)

  1. Steve Baldwin
    February 6, 2013 at 6:51 pm

    Sacrifice the long shots for shorter, easier, more accurate shots. Pays off in the long run.

  2. February 7, 2013 at 7:23 am

    Do it in two sessions. Take only centerline measurements on first day, quickly covering large area and marking stations – no sketching, no details. Enter data on computer and make multiple scaled printouts. Fill in details on the printouts on second visit.

    • Caving News
      February 7, 2013 at 2:34 pm

      That’s an interesting approach. It would likely increase the accuracy of the sketches quite a bit.

    • Gene
      May 31, 2013 at 12:12 pm

      That is interesting idea?

  3. Bruce Zerr
    February 7, 2013 at 2:52 pm

    Sketching – After we measure the distance, using a tape – the next command is “Drape the tape”. (We then “lay” the tape down between the two survey stations. I then sketch, by going up the tape – and using a laser shooting perpendiculars whenever the cave changes shape or form. Lets say that the cave wall on the left side ends in a 90-degree corner 10′ up the tape and 8′ away. Its recorded as 10L8 in your sketch book. I can then just sketch the short distance between the last point and this new dot on the page.

    The result is that my in-cave sketch is accurate to 6″. It looks like a finished
    map. All we have to do is trace in onto the finished map.

  4. Bruce Zerr
    February 7, 2013 at 3:25 pm

    My caver friend and instrument man, Mike Russell, consistently closes his survey loops with an accuracy below 0.4%. If it scores above this level, he has us redo it over on our next trip!

    Mike uses two tricks to achieve this accuracy. First, he reads his compass three or four times before giving me his final bearing. Second, we use 3′ tall staff poles as our stations. This normally give one super solid stations to shoot from one onto the next one. (We don’t use back shots very often.)

    The next trick is that we use 3′ tall staffs as much as possible for our stations – surveying down the center of the cave passage. We only leave hard stations at intersections, corners, or bomb proof breakdown blocks.

    When we come to a place where the cave changes elevation, we then use our poles to go up or down vertically. We don’t use the clintometer to shoot any vertical angle over about 5-degrees from horizontal.

    The result is that we end up with almost zero error closure error from the vertical (clintometer) angle measurement – in loop closures.

    I also ‘sketch’ to scale. It is amazing the feeling one gets when Mike gives me the final compass bearing and distance – and I then ‘draw’ that bearing onto the sketch – to find that on my cave sketch I’m coming within a foot of closure. It means that we ‘know’ we have a good loop closure right then, inside the cave.

    Bruce Zerr
    Eastern Director, Tennessee Cave Survey

    P.S. Thanks Bob Thrun (PSC, Washing D.C) for showing me how to cave survey over 40 years ago. (I still use ‘mylar’, too – though its getting very hard and expensive to find. Now going on 20 miles of underground survey!)

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