I guess I'm kind of old-school in that I still use pencil, paper and Suunto most days. The classics are classics for a reason, yes?
If I'm reading instruments, I usually keep them around my neck. Don't make the cardinal error of putting the instruments on your chest when surveying a crawl; even after years of surveying, I made this mistake over the summer and cracked the facing of my trusty Tandem. Let's chalk it up to not reading instruments often! Anyway, it's better to slide the instrument around to your back and put it down your base layer or wetsuit so it rests between your shoulder blades when you're moving between stations. This accomplishes two goals:
1. It keeps the instrument protected from the mud, it keeps it from swinging around and banging on things, and it keeps it in a location where it's unlikely to be crushed.
2. This is often overlooked, but you need to keep the instrument WARM or your breath and evaporating sweat will condense on the lens of the eyepiece. It sucks sliding a cold, aluminum tandem under your wetsuit and against your skin, but it sucks even more having to try and lick the eyepiece (or remove it and rinse) all the time.
As for sketching, in REALLY wet caves you can use DuraRite instead of Rite-in-the-Rain; it's entirely synthetic and won't eventually wet-out or delaminate like Rite-in-the-Rain does when dunked a couple of times or subjected to constant spray. The downside is it's not quite as nice to write on, smudges easily, and can be fussy when you try to re-draw something in a spot where you've previously used an eraser... but them's the breaks. If you're using Rite-in-the-Rain, no matter how water-resistant they say it is, DO NOT get it wet. Most ear dips can be negotiated with the book held above the water like a waiter bringing a pizza to your table. If you have a swim to deal with, or a really awkward ear dip where you absolutely need both hands, put the book in a drybag or Swaygo pack until you're back in a dry-ish spot. Clipboards will fit in a large Swaygo.
Rule #1 for sketching in muddy, sloppy passage is to never touch anything dirty with your hands. Use gloves when moving between stations or attempting a climb, and remove them when sketching. While sketching and moving through the passage, don't use your hands! Trust me, you can climb better with your feet + elbows + shoulders + butt + whatever, while holding a sketch book, than you think you can. If you get mud on your hands, wipe it on the cleanest thing you can find; sometimes this means I'm reaching inside my coveralls to wipe my hands on my base layer, and sometimes this means I'm wiping my hands on any remaining clean spots on my survey team members. Sorry, guys! :)
There is some value to using a GGG "survey purse" or one of those canvas Rite-in-the-Rain binders, although don't count on the zippers being useful in any way; think of them as condom-style protection against goo. I actually prefer to carry the yellow survey binder on its own, and I slip it beneath my strap of my spare headlamp for transporting between survey stations. The alternative is, well,
carrying it in your teeth or something, which I assure you sucks.
"Although it pains me to say it, in this case Jeff is right. Plan accordingly." --Andy Armstrong