Sunday, October 20, 2013

Air Depletion

This month’s scuba class just got to the part about out of air emergencies.  I think that this was a particularly compelling topic, as the air depletion exercises in confined water were fresh in their minds.  In The Complete Diver, Alex Brylske cites a DAN study of 1000 diving fatalities, in which 41% were the result of the diver running out of air.  DAN reported that 70% of the accidents occurred at depths shallower than 100ft, 40% in the range of 60-99ft, and 30% shallower than 60ft.  One third of the fatalities occurred in depths in which even the newest of divers would feel safe.  So what gives?

Where were these divers’ buddies?  I tell my divers that their buddy should always be visible (don’t get too far apart, especially in low visibility) and in clear water should never be farther than you can swim on one breath of air.  It is easy to address an out of air situation if your buddy is near and equipped with an alternate air source.

What if your buddy is not near?  We are all taught the CESA (or CSA, controlled swimming ascent), controlled emergency ascent in open water class.  In case any of you do not remember, it is one in which when the diver realizes that his air is depleted, and his buddy is not near.  The diver then looks up (who wouldn’t), opening his airway.  He lifts his inflator hose in the air to vent air from his BC to control the ascent, and starts swimming for the surface (duh) saying “AHHHHHH”, or humming, or in some way letting a continuous stream of bubbles escape his lungs.  Allowing the air out seems counterintuitive, but this is the part that keeps someone who is out of air from becoming a fatality.  Boyle’s law applies even if you are out of air. As the diver ascends, any gas in his system starts to expand.  Air that remains in your lungs or body spaces will expand as well.  If the expanding air in the diver’s lungs (alveoli) is not allowed to escape through the airway, the expanding gas will eventually rupture the lung.  Since the gas will find a way out of your body one way or the other, it is in the diver’s best interest to do it the easy way and allow the gas to simply exit his mouth.  Now it is important to note, that through this process, the regulator STAYS IN THE DIVER’S MOUTH.  This is key for two reasons.  First, if the regulator is in the diver’s mouth, water cannot get into his lungs.  This is a good thing.  Second, it is important to remember that when the diver failed to get air when he inhaled, there was likely SOME air left, but it was at such a low psi that he could not draw it into his lungs.  As he makes his ascent, that air, like the air in the diver’s lungs, expands, perhaps providing the diver with another breath.  If a diver is practiced at this procedure and is able to remain composed in the face of an out of air emergency, he should be able to manage a safe ascent and save himself.  Do you practice, even mentally, for out of air situations?

I suppose that this is a skill that many divers simply forget about after certification with a vow to never forget to check their pressure gauges, but here’s the kicker: In DAN’s study, there were two groups of divers who had the most accidents; as one would expect, divers with less than 30 dives and unexpectedly, divers with many (hundreds) dives.  In the less experienced group, I would assume that the diver found himself out of air due to poor planning, poor decision making or inattention to gauges.  When the diver discovers his error, either he forgets his training or panics.  In the experienced group, however, I would bet that at least some of the situations arose out of a laissez faire attitude, or out and out arrogance. The first few moments of the emergency are taken up with the diver thinking, “I can’t believe this is happening to me!” The rules of supply and demand apply to all divers without regard to experience.  An equipment problem such as a leaking high pressure hose is just as dangerous for an experienced diver as it is for a new diver.  Experienced divers should return to the boat with a reserve the same as a new diver because unexpected events, such as reverse squeeze, can happen to anyone and one never knows when that reserve will change from a cushion to a life saver.

I guess the take away is this: It is possible for any diver to find himself in an out of air emergency, but preparing oneself for this can be the difference between life and death.  Follow these rules and you will increase your safety tremendously:

1.) Check your SPG often.

2.) Stay close to your buddy. Alternate air source ascents are easy and will allow you the best chance to complete your safety stop.

3.) Pay close attention to your gear’s maintenance. Address even small repairs as soon as you discover them.

4.) Rehearse out of air scenarios during pool reviews, in shallow open water or at least in your mind.  

5.) Review your open water video, or search Youtube for some demonstrations.

Here and here are two videos I found useful.  Enjoy!

Sunday, October 13, 2013

Go figure!

Go figure!  We learned something again on a recent dive outing!  This time the lesson was on equipment.
We had a new diver join our group.  Ken hadn’t been diving for quite a while and wanted to get back into the sport so he met up with us at Pearl Lake to check out his gear. One look at his gear and there was no doubt that he got certified a long time ago, about 1973, and was still using his original gear.  Now, don’t get me wrong.  Gear, when well maintained, can last 20+ years, but let that same gear sit idly for any length of time and the fabric and anything rubber will start to become brittle and subject to breaking down. Ken was diving a Scubapro MARC VII  regulator and a WATER GILL/AT PAC BCD. As Ken was finishing his first dive, we could see bubbles coming from his BCD.  Upon further investigation Ken found that the inner bladder of the BCD had deteriorated and was actually crumbling in his hands.   Can you imagine the danger had the bladder come apart while he was underwater?  I let Ken use my BALANCE so he was able to get another dive in, so his trip to Pearl was still worth it. 

Another equipment issue was a dry suit purchased on E-BAY.  While Nikki bought a new BARE Trilam Tech Dry dry suit from Manta Divers, her husband, John, got a “deal” on a used one through E-bay. Online, it looked like a pretty good deal; a DUI with newly replaced valves.  When the suit arrived in the mail, however, the bargain started looking a little suspect. The valves looked brand new, but the rest of the suit was well worn, with evidence of several repairs due to leaks. The proof was in the dive. At the start of the dive, John thought that there “might be” a small leak in the suit, but he did not think it was bad enough to abort the dive, so he went on.  When John came out of the lake, however, he bought about 10 gallons of fresh lake water in the suit with him.  Needless to say, John is looking at a new dry suit for next season.  It was an expensive lesson he learned! 

Anyway, we all still had fun and enjoyed yet another day of diving with phenomenal visibility at Pear Lake!

Sunday, October 6, 2013

The Six-ish Things About Gear Storage

On October 6th I will do my last dive of the season. Getting my new hip on Monday October 7th and my next dive will be in Curacao on January 12th,2014.  Generally, as an instructor, the dive season may end but with try scuba and confined water classes my gear never really dries out. It gets used year round. I realize that for the first time in years my season really will end, or at least take a short break. So, like others that end the season I have to store my gear.  It brings me around to the six things that I must do with my gear to ensure it will be good to go when we head off to Curacao in January.

Number 1
Give your wetsuit, hood, gloves and booties a good washing with wetsuit cleaner and extended rinse in fresh water. As a last step, I recommend a 5 minute dip in Mirazyme to kill any residual bacteria that will cause it to develop a stink in storage. After it all is totally dry, inspect the gear inside and out. Look for loose stitching at the seams or tiny tears that could spell trouble down the road. As I teach in my Equipment Specialist class, I like to use Aqua Seal for these repairs. As they say a stitch in time saves nine. Hang your wetsuit on a wet suit hanger in a cool/warm dry place. The rest of the gear can be stored on a flat surface if you don’t have a gear hanger. Put the inserts in your booties.

Number 2
Give your regulator a total wash and rinse. Pour a little Listerine into your second stages to kill bacteria. Make sure to rinse the second stages well. Inspect the mouth pieces and replace if necessary.  Lastly, look at you hoses for cracks, splitting or kinking. Replace if necessary. I like to wipe the hoses with  UV TECH to keep them in shape and extend their life. If it’s time to have your regulator serviced bring it in. Don’t wait until 2 days before your leaving for your trip.

Number 3
Give your mask a good look. Check the straps, frame and lenses. Wash well with warm soapy water using a soft paint brush to get into the folds of the silicone skirt. Dry well and store in the box that it came in.

Number 4
Inspect your fins. Check the straps and clips. After washing in soap and water, wipe them down with UV TECH. It extends the life and color. Store your fins flat with the inserts in the foot pocket.

Number 5
Go over your BCD. Look at the stitching, clips, d-rings and straps. Check out the low pressure inflator. Give the mouth piece the same treatment as your second stages. Give the BCD a good wash and rinse inside and out. I use BC Cleaner on the inside of the bladder and rinse with clear water. To check if the bladder has any leaking problems fully inflate and set aside overnight. If it’s flat in the morning you should bring it in for service. After adding a little air hang your BCD on a BCD hanger next to your wetsuit.

Number 6
Don’t forget flashlights, knifes and computer. They should be washed, rinsed and hand dried with a soft cloth. Wipe the flashlight case with UV TECH and remove the batteries for storage. Nothing kills a night dive like exploded batteries in you flashlight. Pay attention to the knife sheath, making sure it is thoroughly clean. Oil the knife’s blade before storing. Make sure that your computer contacts are dry before storing. More computer battery life is lost by damp active contacts on land the diving underwater. Check your battery in your computer or replace before you travel or start a new season. Batteries usually last about two years, but replacing your battery before leaving for your trip, even if it has not been two years, is cheaper than losing a day of diving.  Remember that batteries discharge over time even when not in use.

Number 7?
OK , I said six things but it’s really seven: Check your travel gear bag. Look for tears, wear and broken straps.  Clean wheels and zippers to ensure smooth operation.  It’s also good to lube the zippers and wheels. WD40 works well on the wheels and we have Zipper Tech available at the shop.