Laser measuring Vs. Pull tape

[barcelonacvr]

We have been using a Disto for about 4 years and love it. It can certainly be done without but the "laser" (we call it the Allen Parson's Project) makes it a lot easier. The price is the biggest down side for me. However, Stanley now makes one that sells for about $100. Preliminary caver testing is good. Some WV cavers are using one. Maybe if Mark Passerby see this, he'll pass the info on here, hint.

Someone in our club has been using one and gave a presentation the other day.Looks interesting for sure and the price is right.I look at it as another tool to use for different things.

[cob]

2) Can be dangerous and need proper working protocols (I've been hit in the eye twice now)

Cindy, I think the "danger" of lasers is a little over emphasized. We use them all the time in construction and I have been "hit" hundreds of times. Has not affected my eye sight yet (things suddenly getting blurry... noe typing by feel... sorry for the mispellings... must sign off...)

Seriously tho, not to down play it, just my own personal experience. (I worry more about the welders)

Having only used a disto undaground once, I have a couple questions:

#1 How tough are the various models? Our caves are rather hostile to technology (once did a trip where 17 out of 23 lights stopped working)

#2 How accurate are they in high moisture environments (like waterfall rooms)?

I definitely see a place for them in surveying, but at this point in time I find it hard to believe they will replace the tape.

tom

[hewhocaves]

a thought... the danger might be greater underground as caving is more or less under low light conditions and theres a greater chance for injury because the retna has farther to compensate than say, on a sunny day outside.

[NZcaver]

a thought... the danger might be greater underground as caving is more or less under low light conditions and theres a greater chance for injury because the retna has farther to compensate than say, on a sunny day outside.

That makes sense. I haven't been got in the eye with a Disto yet, and I'm not planning to test it on myself to see whether this danger is "over emphasized" or not.
I don't really want to mess around with something like my eyesight...

As a general practice, when shooting Disto shots I first call "laser target please", which also serves as a warning to others about what's coming next. (By the way, I find it helpful to have the other person illuminate the target so I know where I'm shooting to.) I then call "laser on - avert your eyes" before shooting the laser. I do at least 2 shots between each station, and if they don't agree within 1/10 of a foot (or a few cm) I keep shooting. And when I'm done, I call "laser off" as a courtesy.

I haven't used one near a waterfall yet, or even in a really misty passage. Anyone else have comments about that? I imagine if you get several readings that agree (and are visible on the target) - you should be set. I've used the same theory shooting through dense tree root forests inside lava tubes, and it seems to work.

[Scott McCrea]

#1 How tough are the various models?

Pretty tough. No moving parts. Some well placed clear packing tape, and it's pretty tight. We still carry our's in a Otter Box tho.

#2 How accurate are they in high moisture environments (like waterfall rooms)?

The laser will reflect (or deflect) of the water droplets or fog. So, it just depends on how much is in the air.

I definitely see a place for them in surveying, but at this point in time I find it hard to believe they will replace the tape.

Yep, they will never replace tape. But they compliment each other nicely.

Now if we could just get someone to make a laser measurer with a compass and clino built in. One push of a button and you instantly get all three measurements.

[hewhocaves]

Now if we could just get someone to make a laser measurer with a compass and clino built in. One push of a button and you instantly get all three measurements.

whats next? little surveying robots? lol

[Cindy Heazlit]

Cindy, I think the "danger" of lasers is a little over emphasized. We use them all the time in construction and I have been "hit" hundreds of times. Has not affected my eye sight yet (things suddenly getting blurry... noe typing by feel... sorry for the mispellings... must sign off...)

No, I must disagree with you. The first time I was hit was direct. I saw a bright flash of light, followed immediately by pain. I felt as though someone had poked me in the eye and my eye was tearing apart. The pain continued for ~1/2 an hour. I ended up with some blindness in the lower left corner of that eye.

The second time was a glancing blow. Just the bright flash, and that was that. Perhaps you were lucky and only experienced the second kind of hit.

In both cases for me, the laser was being used by someone without a background in laboratory science. I guess they didn't know the protocols or cautions when using a laser.

When using a laser, it is really important to establish a protocol. We usually do the following:

1) Call out "ready to target"
2) Other person calls out ready"
3) Call out "targeting"
4) Point the laser at the ground
5) Turn on laser
6) Swing the laser up in an arc from pointing at the ground to the target
7) Hit the measurement button.
8) Call out the number
9) Repeat steps 3-8
10) Turn off laser
11) Call out "laser off"

If it is small passage, the target person turns around in the passage with their back to the laser before holding up the target. Much easier to keep the eyes out of the way.

BTW, it should be LASER not laser (it's an acronym), but I'm too lazy to retype all this.

[NZcaver]

Now if we could just get someone to make a laser measurer with a compass and clino built in. One push of a button and you instantly get all three measurements.

Someone already does make a compass/clino/LASER (Light Amplification by Stimulated Emission of Radiation) device like that...

Check out IKE - http://www.surveylab.co.nz/

[hewhocaves]

ooh! it almost looks like a tricorder!

john

[chh]

I use a distometer and I would recomend them. I use a Leica, but there are some studies out there pitting laser distometers of the Home Depot variety against the more expensive kind. I believe the jury is still out on that. I think the real payoff for the more expensive, scientific manufacturers is water resistance. Tapes still have their uses though, and I always carry one regardless of whether or not I've got the distometer with me. The distometer I have will not take accurate readings through water, for example. Also, some surfaces will not reflect the laser as well as others and may produce errors. It's good to check your distometer against a tape at the beginning of each survey session. The plus side of the laser distometer is that it sure does speed things up! Also, it makes the surveys on dome rooms and the like far more accurate if there isn't any concievable way to reach the ceiling and it is more accurate when trying to estimate the distances of passages that you can't physically fit through. I've also found it quite handy while surveying pits and using the rope as a plumb line. You can take accurate measurements of the walls every x number of meters as you descend which helps when you are drawing up the map.

Now if they'd just combine the laser distometer and the clinometer and make it affordable I'd be thrilled!

happy caving,

-chh

[NZcaver]

.... Also, some surfaces will not reflect the laser as well as others and may produce errors....

Do you always use a fairly smooth, non-reflective (white is OK) target plate when measuring between stations?

If you don't, that could account for some errors. It should be fine to shoot to most wall/floor/ceiling surfaces to get approximate LRUDs, but you really need a target plate for stations. I use a pretty simple design that seems to work well - a 1 foot square piece of thin white packing foam.

Nice avatar, but the way...

[Scott McCrea]

For our target, we cut a piece of white paper slightly smaller than the back of the instrument (Suunto Tandem) and attach it with clear packing tape. Then the backsighter person uses the back of the instrument for a target. I suppose you could use white tape too.

[NZcaver]

For our target, we cut a piece of white paper slightly smaller than the back of the instrument (Suunto Tandem) and attach it with clear packing tape. Then the backsighter person uses the back of the instrument for a target. I suppose you could use white tape too.

Wow! Isn't that a pretty small target to hit (and hold steady on) at anything but very short range?

[Scott McCrea]

We got good aim. Plus, most of our shots, around here, are about 20-30'.

[stashyboy]

Another benefit to those lucky enough to have need, is the act of 'pullingtape' is just that. If one is in a heavily decorated room, often the tape can catch on formations. If there is a flagged trail, surveyers may have to leave the trail to retrieve the tape-not good conservation technique. This happened several times on a recent survey trip in Kentucky. Even if the passage is not delicate, retrieving the tape can be an issue.
-M