Search results

I did the math out of curiosity. Assuming human speech is 60db and we're rounding off the sperm whale click to 230b, there are 17 orders of magnitude of difference. This translates into one hundred quadrillion times more energy. Quadrillion.

My impression from the story is that the freediver reached out and was in physical contact during the click, so the vibrations were conducted through him.

I absolutely believe it. In a very reductive nutshell, a decibel measurement (dB) expresses the acoustic energy of a sound. Importantly, decibels are logarithmic and increase in orders of magnitude (log10). Human speech is usually 40-60 dB. A rock concert is going to be at least 100 dB. The...

@Germie - the recently-retired NSS-CDS cave curriculum included decompression training for very short accelerated deco (15 minutes). There are a lot of Florida caves where that allowance is adequate or generous for beginners. The newly-adopted standards require high-O2 and decompression...

Quick version: we repeat the lost-line drill at each of the three levels of the course* before qualifying to move up. Succeeding at the next level may involve a longer distance, negotiating reasonable obstacles, demonstrating better reel technique, improved buoyancy management, etc...

That rock, I know it well. It took me six tries to nail the drill at the Basic level (the buoyancy/balance issues from my drysuit were making good execution impossible). I actually set a new student record for number of procedural failures during my first trip. Happily, I nailed the Apprentice...

I'm going to make a supremely original contribution to the thread and suggest.... the Mares Avanti Quattro.

The biggest change that I made between Cave Trip #1 and Cave Trip #2 was to ensure that I had a firm, solid grip before I started the pull. I think it's the micro-sliding from suddenly bearing weight/force from a pull that wears fingertips off in sheets.

Thirding PDM. Get a mask that fits you well, and then have custom lenses for your prescription bonded to the glass. They can remove and replace the bonded lenses if/when your Rx changes. My mask is a TUSA Visio Pro (comfiest skirt on the market, IMO). The lenses have a huge field of vision, are...

I have a new pair of ScubaPro Jet Fins with about 12 dives on them. Getting the fins on, no problem; getting them off is a production that may involve 1-3 additional divers. The springs are incredibly stiff and it's hard to get good purchase to slide them over the heel of the boot. Is there any...

I can't believe that I've been missing this thread! I'm delighted to hear that Reggie, Harry, and crew have been able to make cave diving work for you. I'm hoping to head back in March (lacked funds for December) to finish up Full Cave. Perhaps we'll find some time to dive together? :) Tell...

Wazee Sports is closing?!

I'll be very interested to see the results of the EEG study! One of the more interesting theories that I've seen about narcosis* is that the fatty myelin sheaths around nerves have excellent nitrogen uptake. Once full of nitrogen, their physical properties change and the cognitive impairment of...

Not DDM and not a doctor, so feel free to tell me to shove these thoughts wherever you please: The challenge with piercing-related infections in the ear cartilage is that it is an EXCEPTIONALLY low-vascularized part of the body. There aren't very many blood vessels and not much circulation...

This is a modified interpretation of the @kensuf chart of the lipid solubility values: Landmarks on the solubility scale: Oxygen is ~7x more soluble than helium. N2O is ~14x more soluble than oxygen... ...which works out to N2O being ~104x as soluble as helium. Nitrous oxide is about 16%...

After a cup of tea (and some grad school insomnia), I decided that I liked the data as a graph: Following the 1ATA = 1 martini rule, we can see nearly two drinks' of difference between EAN21 and 21/35 at 150' (45m). Know anybody who thinks two drinks make no difference behind the wheel?

[Background] This is a very rudimentary look at a single aspect of gas planning: the narcotic potential of the breathing medium. Gas narcosis (whether N2, O2, or CO2) impairs divers' cognitive functions, which poses safety concerns. Understanding/mitigating the risks posed by narcosis is an...

I'd like to quote myself from a different post on a similar topic:

"Spongehenge" is now on my bucket list, primarily for the name.