27th. December 2013 – 11:30: Where's the sand from the sand-pit?

Ok, so you’re in the water. True it’s a sand-pit without sand.  You know how a baby feels when it has lost its pacifier. After much angst, the dummy, sorry second stage, is safely back in my mouth. Only now, I have to replace it with the snorkel mouth piece.  Time to spit the dummy. What next? The confined water skills of course.

Surface neutral buoyancy.

This is where my BFF and weight-belt lock horns. Like all battles, it was not 100% pure science.  The antagonists are big players:nature and science. Archimedes stepped into the bathtub; we stepped off perfectly good Terra firma. He noticed something; so did we. The only difference is that he noticed it first and it was ground-breaking science. To us rookies it was merely a quod erat demonstrandum derivative moment. Mercifully, the trade-off was that  we no longer had to run around in our birthday suits crying “Eureka”, which in dive speak is the same as yelling "Shark". An instant pool-side evacuation is guaranteed.

For now, I was content to play the pacifist and let BFF and weight-belt face each other off. As long as the surface of the pool was at eye-level and I could remain neutrally buoyant by merely holding my breath with a deflated (sic..defeated) BFF, I was happy to remain in the DMZ and let Archimedes do all the work. He’s going to win anyway.

The five point descent.

The human brain (at least mine that is) is a strange creature. When it was relaxed sitting pool-side, the instructions made total sense. Who could forget the word “SORTED”, which is the acronym for the five point descent? What it stood for was just as easy to remember.  Reader I refer you to:

<Scuba Diving Acronyms>

for the five point descent only. More of this later when it’s time to climb back up.

It all made sense, that is, until you actually hit the water. When you’re in the water, fiddling with your mask because a fly has gotten in somehow, buoyancy negative, regulator or snorkel not purged, water defying gravity and trickling up your nose, pool-side instruction started to make total nonsense.

Why was it called the five point descent when there are six letters in the acronym? Oh that’s right; you didn't need the ‘T’ because you’re “guaranteed” water-proof watch had stopped working so you can’t note the time. Ditch the ‘T’, five letters - that figures.  You were descending anyway that’s why it’s called the five point descent and not something else like the “six point swimming horizontally with a bunch of stuff strapped onto your body and a fly for a passenger”.  So you might as well drop the “D” because "descent" was too obvious.

What you were left with was "SORE". Yes that’s got to be right thinks I. That’s exactly how I felt. I’m sure my passenger Louie felt the same way too.

At least that’s what your brain was telling you. But hold on a second, were there not six letters? And what was the task associated the fifth letter? Wasn’t there something about: Elevate and Exhale mentioned in the good book? Oops, that’s two ‘E’s! Now, I was more confused. The acronym for the five point descent should really be “SORTEED”. Now where’s the dictionary when you needed one? This must be a typo in the PADI manual.  Too late, had to go with "SORTED" because I was actually descending.

Not quite text-book, you must understand, because I let way too much air out of BFF and it was too late to correct the obligatory but inevitable rookie thing. The fly has landed; with an ungraceful thump, at the bottom of the pool. Thankfully, I was still breathing. Perhaps there were letters missing off the end of the acronym that the instructor did mentioned but I didn’t pay attention to because I was too busy with equalizing. Oh dear one more letter for the five point descent. Nah... way too many ‘E’s in the acronym. If "SORTED" was good enough for PADI, it was good enough for me.

What I was too busy to have noticed was that Louie had decided abandon my mask, exit - stage up, skip the 101 class and move on to the five point ascent because he knew what was coming up next and I didn’t.

Clear your mask.

So that’s why Louie deserted his host.  The instructor pointed his index finger at my buddy and I. Then he held a stop signal, followed by pointing his index and middle finger at his eyes and then pointed to himself. So it began a textbook and flawless partial mask clearing demonstration followed by our attempt:

Step	What the Instructor did	What I did on my first attempt
1	Lift the bottom of the mask slightly	Lift the bottom of the mask as far as possible.
2	Let a little water into the mask to partially flood it.	You guessed it.
3	Re-seat the mask on your face	Got that right
4	Look up tilting your head back	Kept my head straight and rolled my eyeballs up into my skull.
5	Place a slight pressure on the mask above the eyelids.	Place a lot of pressure on one side of the mask above one eye.
6	Blow gently but continuously through your nose until you see all the water disappear from inside your mask.	Create a hurricane with your nose inside your mask. (Thankfully Louie didn’t hang around)
7	While doing all the above don’t forget to keep breathing through the second stage.	Say what?

Just when I thought that that was that, variants on the same theme manifested. There was the full mask flooding and clearing, mask removal and replacement and if that wasn't enough, swimming with your mask removed.

It was while holding my mask the furthest away from my head under water as it had ever been, I began to muse:

“Alas poor Yorick, I [thought] I knew him well...

he hath born me on his back a thousand times...”

I contemplated my reading on how high-tech this simple device really was. From the perspective of the exercises we had just been through, two things became patently clear.

The closer the mask lens is to your face, not only does your field of vision increase, but there is also a lower volume inside the mask. The lower this volume, the less water gets into your mask and as a result, the less water you have to clear. Low volume masks are typical of the ones that free divers use. I noticed that the mask my instructor was using was very similar. A low volume mask is however a double edged sword. It does not take much water to completely fill such a mask. For this reason low volume masks tend not to be suitable for inexperienced divers as they could be too preoccupied with clearing their mask more often than is really necessary. 

Whether or not the mask leaks water at all is dependent on the softness of the silicon composition around the skirt of the mask. The softer its composition, the more effectively it seals against your face. If this seal is effective, and it usually is with most modern masks, then a low volume mask makes perfect sense, even for scuba diving.