Tony Anders
Caver
SKSC Caver
See you around, in the underground.
Posts: 329
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Post by Tony Anders on Oct 6, 2006 9:40:58 GMT -5
Can anoyone on here tell me what is the best compass to use for caving. I have a sylva that I use for backpacking and I have used it underground. However I hope to get it a better one of second one for caving. I would like to get an inexpensive clinometer for us to use when we map unexplored areas that we don't have on the maps we have. Does anyone know if we can make a clinometer with a protractor or any other way. I seen a Suunto MB6 match box compass, clinometer but the price was so cheap I didn't know if it was a true clinometer or not. If you will, get back with me and let know about some of this stuff, I would hate to get inside a cave and get lost due to a faulty reading on a compass. See you around  in the underground Tony |
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Post by Karsthuntr on Oct 7, 2006 10:11:59 GMT -5
First 3 on this page is what most cave surveyors use. Click Here |
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Post by Azurerana on Oct 7, 2006 22:26:43 GMT -5
Just about any water resistant sighting compass with 1 degree error will do, assuming you use backsights.. Whether or not you prefer the compass/clino block, or as two separate instruments is up to you. I prefer them separately, as then you can have two people easily do compass and clino without fighting over the instrument. Aluminum housings are better than plastic housings. Some have a prism to light the inside of the compass, some have a slot for an earring sized lightstick. Most people I know use Suunto brands.
In general, the most imporant part is the eyes behind the instrument. If you are meticulous, you can do a good map with a cheap compass and a clino consisting of a protractor, a level, a string and a hexnut. If you are sloppy, all the finest most expensive instruments won't save you.
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Brian Roebuck
Site Admin
Caver
Caving - the one activity that really brings you to your knees!
Posts: 2,732
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Post by Brian Roebuck on Oct 8, 2006 9:16:16 GMT -5
If you intend on cave surveying make sure your source of light used to illuminate the compass does not get too close to the compass during reading. The batteries can make the needle swing if it gets too close. Also there can be metalic rock in caves that can affect compass readings. If all you are doing is navigating through caves taking notes, sketches, rack cairns, and other non-permanent natural marking methods can help you find your way back out. Remember to frequently look back the way you came especially at intersections and when you pop out of small spaces.
Have fun!
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Post by Azurerana on Oct 8, 2006 11:42:13 GMT -5
Re Dr. Beaner's remark: this is assuming your light source is electric. I still know of surveyors who use carbide only when on compass for this very reason. You can probably google on LEDs and Surveying to find some discussion whether or not small LED lights (like those one LED, one button battery squeeze lights) have enough current draw sufficient to create a disruptive electromagnetic field.
Don't be afraid to experiment--though obviously not on that one-time permission only survey in Mondo Caverns. Since in many instances, you will be focusing on a point of light station on the other end, you only need enough local illumination to read the compass (though of course you shouldn't move through the cave without standard illumination.
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Post by Karsthuntr on Oct 9, 2006 18:20:59 GMT -5
Re Dr. Beaner's remark: this is assuming your light source is electric. I still know of surveyors who use carbide only when on compass for this very reason. You can probably google on LEDs and Surveying to find some discussion whether or not small LED lights (like those one LED, one button battery squeeze lights) have enough current draw sufficient to create a disruptive electromagnetic field. Don't be afraid to experiment--though obviously not on that one-time permission only survey in Mondo Caverns. Since in many instances, you will be focusing on a point of light station on the other end, you only need enough local illumination to read the compass (though of course you shouldn't move through the cave without standard illumination. Yes the little LED lights affect the compass. I use the little super bright LED attached to my clino and a piece of fiber optic cable streched over to my compass. Works great and doesn't afect the compass or the sighting. |
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Post by madratdan on Oct 10, 2006 8:24:22 GMT -5
Your set up sound interesting. do you have the two instruments taped together or are they connected in some way?
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Post by Azurerana on Oct 10, 2006 9:10:38 GMT -5
I experimented: the little squeeze light I have has about a 1 degree sway afffect the compass when you are touching the case, but has no noticeable effect when held at 3 inches away. The effect seems to come from the battery, not the light itself. Seems there could be a workaround for this.
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Post by Karsthuntr on Oct 19, 2006 21:04:34 GMT -5
Your set up sound interesting. do you have the two instruments taped together or are they connected in some way? They are seperated and connected with the fiber optic cable and the string. |
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