Measuring distances solo

[alanf]

Does anybody have any tips for measuring distances solo. Measuring unknotted line shots is my priority right now but cave width will be added to the list soon.

I could use a reel with knotted line and overlay the existing line. I suppose, but if I'm going to all that effort maybe I would be better using a tape. I really don't know but I am sure that to many of you this is all old hat.

[CaveBuddy95]

Hi Alan,
maybe this article on Quietdiver.com may help.
Although survey KL can be straight forward, a non KL, solo, can be a challenge!
Good luck with your project.

Saludos,

[Webmaster]

You'd pretty much have to anchor the tape, swim it out to the next station, then free the end and reel it back up.

A lot of back and forth, but surveying solo even in air filled cave is a pain. It's much more efficient in either case with at least two people.

[SuPrBuGmAn]

You're gonna be better off with knotted line solo...

[FW]

You're gonna be better off with knotted line solo...

I would run a parallel knoted line, before I would do all that swimming back and forth. The small sonar units work OK for estimating passage width, unless they are really wide.

[traveler]

I would run a parallel knoted line, before I would do all that swimming back and forth. The small sonar units work OK for estimating passage width, unless they are really wide.

Agreed on both counts.

Another trick with the sonar units is that at selected locations, you can take shots at multiple angles to get a sense for the size and shape of the cross-section. For example, if your station is on the floor then you might shoot left, up, right, and the 45deg angles between those shots.

_\|/_

It's not generally practical to do this at every station, obviously. Also, the sonar can be finicky, so it's not a bad idea to take two readings per shot, and if the values aren't close then take a third to see which one is wrong.

This sort of thing is useful in conjunction with a flowmeter, to allow an estimate of volumetric flow based on velocity. However, it's also good for drawing nice maps of caves with large passages.

[rotor60driver]

If necessary you could also attach a snap ring to the end of your tape and snap it to the existing line, then swim out take your measurement, swim back and reel in the tape and start all over again.

[CaveBuddy95]

...and if really you can't do it alone, you can pm me and I'll be more than happy to hold the other end of the measuring tape!

Saludos,

[FW]

...and if really you can't do it alone, you can pm me and I'll be more than happy to hold the other end of the measuring tape!

Saludos,

Best answer yet!

[alanf]

Best answer yet!

Very True! I have contacted Jason privately.

The idea of measuring sidewalls with sonar intrigues me, but I don't find so much information immediately. What sort of distances work?

I see a sonar gun on Mike Poucher's site. Does anyone have some links for these devices or suggestions of what models and makes to consider.

Thanks very much for all the help so far.