[Therion] Ariane's line - Underwater cave survey device

[Tarquin Wilton-Jones]

> It's called "Ariane's line", you can find more details on this website:
> arianesline.com <http://arianesline.com>

MNemo is the main piece of kit.
Looks like it is a device you clip onto your dive line. As you swim, it
counts how much line it has been pulled along. It records compass,
length and clino/depth.

Basically that's just a normal survey, either in regular data format or
in diving format (your choice). Survex and Therion can both handle
either of those data formats. You just need to set the right "data"
command. You would need to convert from Excel to Survex/Therion format,
or ask the devs to export it natively. Should be simple to do.

The loop closure of 2% is because you have to unclip it from the line at
a tie-off, then clip it back on again on the other side, so a small
amount of length goes missing. Also if the line is not tight, the
bearing or clino can be wrong. Same if it wraps around a curved
wall/floor. Still, that's better than most diving surveys. Looks like a
really cool device.

Cheers,

Tarquin