Some Recent Photos

Prince Albert

Who can stay longer on one tank?

Entry Point

Buddy in Mr. Bud 

Angle on a Wreck

Honduras

Success !

Melatonin and Susceptibility to CNS Oxygen Toxicity by diversalertnetwork

Melatonin and Susceptibility to CNS Oxygen Toxicity

Seizure due to CNS oxygen toxicity in divers breathing a hyperoxic gas mix underwater is very likely to cause drowning. Some anecdotal reports indicate that CNS oxygen toxicity may be more common during night activities. A research team from Israel Naval Medical Institute in Haifa, studied the effects of night activities and melatonin on possible modification of susceptibility to oxygen toxicity in rats.

Melatonin is widely present in animal and plant species, however its physiological function differs depending on the organism. In animals, it is produced by the pineal gland and is associated with regulation of diurnal (circadian) rhythm. With the onset of darkness, the pineal gland begins secreting melatonin reaching maximum production in the early morning hours and stops with the onset of daylight. Melatonin promotes sleepiness and contributes to a healthy and restorative sleep. It also contributes to antioxidant and anti-inflammatory processes.

In this study, rats were exposed to 12 hours of light/dark cycles to affect melatonin production over a three week period. The control and experimental groups were kept awake during the day and night, respectively. At the end of this period melatonin level in the blood was measured. Each group was divided into two subgroups, one receiving supplemental melatonin and the other a placebo before exposure to 5 ATA oxygen in a hyperbaric chamber. The time to onset of convulsions was measured. In addition, researchers measured the levels of enzymes affecting reactive oxygen and nitrogen species.

Oxygen convulsions occurred much faster in animals active at night. The rapid onset of convulsions was associated with a reduced level of melatonin. However, provision of external supplemental melatonin did not affect resistance to oxygen toxicity. The effects of external melatonin on the level of antioxidant enzymes varied. Oxygen reactive species were more affected than nitrogen reactive species.

The most important finding of this study was that night activity represented an additional risk factor for the development of CNS oxygen toxicity in rats. This was likely caused by changes in diurnal rhythm which could not be compensated by administration of external melatonin.

For divers this raises the question of whether diving at night increases the risk of oxygen toxicity as well. Although taking melatonin before a night dive may not provide any preventative benefits or protection against CNS oxygen toxicity, it can be beneficial in other ways. Melatonin may help with jetlag by supporting a healthy sleep cycle and by re-setting the body’s sleep-wake phases.

References

Eynan M, Biram A, Mullokandov M, Arieli Y. Susceptibility to CNS oxygen toxicity following a switch from day to night activity is associated with changes in melatonin and antioxidant enzyme activity. Oral presentation, EUBS 2015, Amsterdam.

Bon Bini, Bonaire!

Just for the fun of it!!

The reason we dive, is because it is just so fun! Whether you are photographer, technical diver, sightseer or any other type of diver, we dive not because somebody is compelling us; but because we love to dive! If you are like me, there is an inexplicable internal compulsion to dive. So here is a little info on one of my wife’s and my favorite spots: 

Bonaire

Bonaire is part of the Netherland Lesser Antilles, which used to include Aruba and Curacao. Each island now has its own political relationship to The Netherlands. Bonaire is a Special Municipality. (I am not sure that means by the way!) The small desert island is located about 50 miles off of the east cost of Venezuela. The climate is wonderfully dry and warm. And the inhabitants are just as warm and welcoming. The beaches generally are covered with broken up coral and not really ideal for sand castle engineers. But the water, animals and reefs are ideal for diving!

(Can you see the octopus?)

The first time Coleen and I dove Bonaire we found the amount of fish on unbelievable! I mean, our comments were: “if we try to tell anyone how many fish there are, they won’t believe us!” And it is still true today. The shear amount and variety is nearly overwhelming. On our very first trip Coleen made an underwater friend of a rather large puffer. This fish followed her all dive long, just hanging out staying within about 10-20 feet of her. Two days later we decided to dive the same spot and sure enough, her friend was back at her side. … Well, I suppose it was the same fish!

Coleen and the Puffer

Finding the dive sits is so easy and fun.

There is little reason to pay for a boat (see below). Most dive packages come with a truck or SUV equipped with lay down tank racks. Load up and head down the coastal road (it is about the only road). Look for rocks painted yellow alongside the road. Each site will have such a rock. You will find the name of the site painted on the rock.

Hilma Hooker

Invisibles

Oil Slick

 Gear up and go. Expect an easy beach or dock entry with a 25-50 yard surface swim to a buoy. The buoys are typically in approximately 30-40 feet of water and on the edge of the reef. A perfect starting spot and an easily found exit point. If you remember how to use your compass, take a heading from the entry and return on its’ reciprocal, and voila, you are back where you started!

It is a good idea to spend a few dollars and buy a dive site book for Bonaire. Lonely Planet publishes the best one I have seen for Bonaire. Some of the dives are rather challenging and few are downright dangerous. The current on the end of the island will take you to Venezuela if you miss the exit! Well, that’s what I have been told. 95% of the dive spots do not have any appreciable current and are easy to dive.

There is a great wreck, the Hilma Hooker. It was an inter island freighter last used for the drug trade. The 145 foot ship was abandoned in port after the authorities showed up. The ship started to take on water while docked. So it was in the process of being towed when it went to Davy Jones’ locker in 100 feet of clear water, landing perfectly in the sand between the double reef systems. This means it was NOT cleared of entrapments and can be nasty on the inside. If you are not wreck certified, admire all the wonderful sponges and fish on the outside. But stay out of it! Even if you are wreck certified, be very careful. I recommend you find a dive instructor to make your first penetrations with. Ebby Jules at Belmar is an excellent choice. With a max depth of 100 feet and a lot of good diving at 85 feet, this can be a long, fun dive. We did a deco on it last November and just had a blast.

Hilma's Port Side

The East side of the island has some of the most beautiful and rugged shore line you may ever see. No beach entries over there. You can get a ride on an inflatable boat and see the underwater world as well. Frankly, it is very nice diving, but I do not think it is worth the $150 when compared to the rest of the island.

East Coast

There is small islet just opposite of the main city of Kralendijk (pronounced “crawl-in-dike”). The islet is Kilen Bonaire. It is a 5 min boat trip and has some nice spots. You are likely to see the fabulous and entertaining sea horse on the trip. Again, I am not too sure it is worth the money.

(This is all I have seen Sea Horses do by the way)

The reason I am not real big on the two boat trips is simply because the rest of the diving in Bonaire is just a fabulous and does not eat up your money.

(Not a recommended practice)

Most safety stops can be done on the reef or in the sandy bottoms between the reef and shore. The water is very warm and life is abundant. I have been known to breath my tanks down rather low (not recommended) while chasing photos of the creatures in the shallows. I also made a new best friend in the shallows: Miss Fire Coral. Not particularly pretty and has a rather nasty disposition. … But there was a baby spotted eel making a home inside. I just had to get the picture. Oops. A little closer than I thought! … And the picture? I never did get it!

(Can you identify the fire coral? I CAN!)

Speaking of which, it is against the law to touch the reef or wear gloves or take game. I have never seen an underwater police officer. But following the laws and keeping a healthy distance will not only prevent you from damaging the reef but will also keep you from inadvertently bumping onto my new best friend!

Buddy dive centers which owns; Buddy Dive, Belmar Apartments (our personal favorite- Belmar- Managed by our good friend Chrissie Wooton) and the Caribbean Club Bonair, has a drive thru tank refill center. Just drive up, toss your empties and grab some full tanks and off you are. A note here, if you are diving Nitrox, be sure to take the time to analyze the gas. I was there November 2012 when Buddy was apparently training a new mixer. The mixes were way off.  This was the one and only time, and it was only on one day, I have seen this problem. None the less: Check! We were getting 4 to 4 ½ hours underwater in four dives each day with bottoms of 75 to 100 feet on every dive. Your Nitrox mix is critical. If you are not currently diving Nitrox, do it! You can do it at Belmar or prior to your trip. But do it!

Eating:

Some of the Best NY Pizza, Ever!

This is my second favorite thing to do on a dive trip. There are several GREAT restaurants in Kralendijk. Dutch, Argentine, Sushi, Fish, Brazilian, NY Style Pizza and even a KFC! (Wow, if you go all the way to Bonaire and eat at the KFC. Please don’t tell me. Just slap yourself in the head for me.) I grew up on the beaches of Southern California and love fresh sea food. The island’s best fresh fish is not found in Finney’s Fresh Fish Diner, but in “It rains Fish”. You may need to make reservations weeks prior to you visit, to be sure you can eat there. 

So all in all Bonaire is wonderful place to dive and relax! I can't wait to go back! May be we will see each other there!

Bon Bini

Relaxing at Oil Slick

1

Epilepsy and SCUBA

Epilepsy and SCUBA

I am surprised about the number of questions I have been asked as of late regarding whether it is safe for Epileptics to SCUBA dive or not.

Let's first look at what epilepsy is:

The Mayo Clinic defines epilepsy loosely as follows: .... Epilepsy is a neurological disorder where the nerves become disturbed. These disturbances can lead to seizures, unconsciousness, abnormal behaviors, disorientation and sensations. "Even mild seizures may require treatment because they can be dangerous during activities such as driving or swimming."

The seizures (what we are most interested in here) are caused by a Paroxysmal Depolarizing Shift. Normally brain activity is non-synchronous (neurons firing independently of each other) but in epilepsy the neurons fire in a synchronous manner. Like waves of impulses flowing through the brain. This depolarizes the ion inhibitors of the excitability neurons giving rise to uncontrolled neurological impulses which cause seizures. 

The closet example I can think of is the result of pouring a soda on your PCs mother board. ZZZZAP!

As the seizure ends a new and very dangerous phase for SCUBA divers begins: The Postictal period and will commonly last 3 to 5 minuets. It can last for hours. It is characterized by confusion, disorientation and fear. In 6%-10% of patients Psychosis will occur.

Approximately 1 in 100 Americans will have epilepsy. It takes at least two seizures to base the diagnosis. Treatment, which generally includes medications or sometimes surgery, may eliminate or reduce the frequency and intensity of seizures. There are not any immediate underlying causes for epileptic seizures.  Epilepsy cannot be cured, but the symptoms can be treated in about 70% of the cases.

The seizures can be brought on by many different stimuli. Stress, increased levels of O2, unpredictable light patterns and other seemingly random stimuli will be on that list. And what is more, what caused a seizure one day, may not cause it another day. And vice versa.

People with epilepsy are at an increased risk of death; this increase is between 1.6 and 4.1 fold greater than that of the general population.

So how does all this effect SCUBA divers? Significantly. One cannot predict a seizure, its strength or duration, the seriousness of the Postictal period or the variables which will initiate a seizure.

So what do your think? I think the answer is NO! Not on my boat for sure!

The vast majority of divers who lose consciousness, while underwater, drown. And that is not good. More over the meds used to treat epilepsy are CNS depressants, and these are generally contraindicated for diving. Just like alcohol and barbiturates.

Any form of unconsciousness at depth is deadly and there is NO SUCH THING as "a small seizure".  Remember, drowning is not the only possibility here; over expansion and uncontrolled decent and ascents are among the realistic possibilities for the epileptic diver and any would be rescuer.

 DAN recommends that the diver be off all related medication and free from seizures for 5 consecutive years. And then to have a buddy who is well trained to assist a violently seizing, disoriented diver at any moment and be able to preform all surface rescue needs including extraction from the water. 

My personal comment: please don't dive. I love diving, but it is not worth putting others or myself at such risks.  

An apple a day: Healthy Habits for Diving

I have always been interested in fitness. As a young man, it was all about competitive sports, most especially football and baseball. As a little boy at the beginning of games my mother would make sure my jersey was tucked in, my ball cap or helmet was on straight and that all was in order. Then this sweet daughter of Ireland would look me in the eyes and say, “remember honey, winning is not everything, but loosing is nothing”.  Yes, the youngest of three athletes who, like our father, all played college ball; we grew up rather competitive! We all played a host of other sports, tennis, racquet ball, squash, gymnastics, golf (the world’s hardest game!), 1 and 3 meter diving and more. Even my wife Coleen was a competitive figure skater and college tennis player. There was never a time we played to lose or “do our best”. Just win. Like my greatest football coach exclaimed after working himself into a foaming mouth; “…the only thing that matters at the end of the 4^th quarter, is the score!” Our poor children did not have a chance! To them, second place is the first loser!

As I have grown older, the accumulative results of years of injury and surgeries have forced me to behave a bit saner. (Although, after breaking 4 vertebrae at Colorado’s Mary Jane in my mid 40’s Coleen asked me if I could live my life over, would have I have done athletics differently. Of course, I responded, I’d been 10 times more intense!) Well, anyway, now it is all about fitness. I don’t care to try to live longer as much as I want to enjoy each day and die healthy. So here are some ideas from " Doctor Farr,The SCUBA Instructor”.

The Starting Place:

Estimate where your physical abilities are, and ratchet down a bit from there to find a good starting place. A visit to your doctor to discuss your goals and methods may well be advised first.

Perhaps the place to start is with this thought:

Avoid Injury: Not only in the world of SCUBA, but in the world as a whole. Injuries can pose some challenges which may complicate your life and lengthen the road to your goals. They can also make SCUBA diving difficult and increase the chance of DCS or re-injury. And that is never a good thing! Weakened muscles, vertebral disks, tendons and ligaments are prone to subsequent injury and also may have a more difficult time exchanging gases due to scar tissue or vascular impairment caused by the injury and the healing process. This may also be true of mended bones. If your back is like mine, it injures more easily now than before. Well, actually this is true of my entire body. Just this week I helped a friend and patient of mine move an older, large, tube style TV. I am still paying the price in pain and loss of mobility and strength. I was planning on making some dives this coming weekend using twin 80’s (about 75 lbs/34 Kilos). Not now. There is no way I am strapping those on! Singles will have to do.  I am rather disappointed. The other impact of the TV faux pas is this; I have to retreat some on my daily exercise as well. At 56 years old, I just do not heal like I did in my youth (or as in my 40's either.) Remember, stay well within your limits. I will make continual examples of this principal throughout this post.

Set Reasonable Goals: When I was 45 years old, I used to get in the “leg sled”, you know that chair you sit in at about 45⁰ angle and use your quads to push weights up to a full leg and foot extension.

This is not the sled I used. I just like the picture!

 I always did 3 set of 10 reps, 985lbs/445K on my lite days and 1075lbs/488K on my heavy days. Now, I don’t do it at all. In place of running 10 miles/16K I swim 2,000 yards/1828 Meters and sit on a recumbent cycle for 45 min. 15 pull ups in the place of free weight standing curls, etc. etc. etc.  As competitive as I am, it can be difficult to swallow.  But trying to relive my former days would be crippling.

Cardiovascular Training:

Let’s face it; you do not have to be in good shape to dive. We have seen the diver wearing the weight belt which is three feet longer than you are tall. I don’t even want to know how much lead they need to wear or breathing gas they use. But, they are enjoying themselves and that is the point, isn’t it? Don’t you imagine how much more enjoyment these divers would have if they did not struggle with poorly fitting gear, getting winded just walking a short distance and could use less gas? Not to bring up, that according to DAN heart attack is the most likely cause of diver fatalities. So what is good cardio training? For most adults non or low impact training is the better way to go. They include speed walking, cycling, swimming, elliptical and stair master machines. I am sure there are others. Each has advantages and limitations. So perhaps a mixture is the way to go. Cycling is emphasizes quad strength, but does little for glutes and abs.  Swimming increases range of motion and “lengthens” muscles but is limited in fat loss. Speed walking gives good leg and hip exercise but can aggravate joints and damage your meniscus. And none of them do much for your upper body. However, they all can get your heart rate up where it needs to be and minimize the chances of injury when compared to running, step aerobics and “plyometric” style exercises. It is useful to keep in mind, that the majority of the benefits of all aerobic training ends when your heart rate decreases. This is why resistance training is a good idea.

Resistance Training:

The classic resistance training is weight lifting. I would still use free weights if I could. But I can’t do much with them because of my back. So I use the machines; and only the ones that support and protect my spine. I still can get a surprisingly good workout! Chest, glutes, arms, shoulders, legs. You name it. I even get in 15 pull ups. The one thing I must avoid is any axial compression (compressive forces to my spine). Why, resistance training? Not so you can look like a body builder, but for fat burning. Here is how it works. Muscles require protein to build and repair. They burn sugars to contract. (All muscles do is contract by the way.) But at night, when you are fast asleep, they repair and grow bigger. That is right. And guess what they use for energy? Your fat stores, especially when you have not eaten any carbohydrates in the evening and just prior to going to bed. This is why a healthy combination of aerobic and resistance training is the best way to lose weight and get fit. Ask any trainer. They may not understand all the physiology and cellular biology behind it, but they know the results like few others.

Stretching:

There is nothing in fitness I dislike more than stretching. Yet, if I skip on the daily minimum I need, I will know it all day long. The benefits of stretching include, better range of motion, preventing and relieving muscle spasms and “stiff muscles”, increased vascular circulation, recovery and healing of tissues and real importantly, decreasing the chance of injury. I am sure there are more. There are some important things to remember about stretching. You can hurt yourself by over stretching. By both the distance your stretch and intensity you stretch with. Always be able to breathe easily at any given point in the stretch and you will mitigate the chance of injury.  It is very important to enter into and exit out of stretches slowly. Our muscles are equipped with a protective reflex called the proprioceptive reflex; in the area where your tendons and muscles join there is proprioceptive sensor which is sensitive to sudden stretching. When suddenly streached it sends a quick message to your spinal cord which responds by causing the associated muscles(s) to contract. Even if when we force our way past the reflex, the message is being sent. As soon as you relax, the muscle will actually tighten, undoing all the good and more you have done. The result is a less flexible muscle! Oops!

Perhaps the best way to stretch is by using either Yoga or Ti-Chi. Both, when taught by a responsible instructor will be very beneficial and frankly, kick your butt! These are exhausting and are actually a great way to burn calories. My youngest daughter (a former Junior Olympic level volley ball player) now teaches Yoga. She alters poses and moves according to my limitations. It is the best thing I have found for my back health.

Diet:

It is such an ugly word, isn't it? I am not talking about going out and finding the latest, greatest fad, but rather a permanent behavioral change. It is not all that hard once you admit the change will be good for you. Look at the bigger picture than what is on your plate. For example: did you know people who smoke have about two times the mortality rate than non-smokers? While the medically obese have 4 times the mortality rate of non-smokers who are not obese? Who would have thought all that delicious food poses a greater threat to your health than tobacco? Trim and fit people live healthier and longer. They also have an easier time maintaining ideal buoyancy, use less energy, breathing gas, wear less lead, don’t have to spend extra money on special order equipment and save on the food and drink bill. Hummm, no down side here.

Look at populations with good eating habits: Latter Day Saints (aka Mormons) abstain from alcohol, tobacco, coffee and black tea. They avoid caffeine, excess meat and emphasize, whole grains, fresh fruit and vegetables. They also enjoy some of the lowest levels of cancer, heart disease, diabetes etc. while living longer and healthier than nearly any other group. This pretty impressive considering most of Latter Day Saints live the industrialized countries of North America, Central and South America and Western Europe. Areas not know for low rates of illness. There are of course other groups to learn from as well: Seventh Day Adventist and other vegetarians and certain limited areas of Asia. What do they have in common we can learn from? They don’t over eat, they eat more natural foods less processed foods including whole grains, fresh fruits and vegetables, nuts and fresh dairy with minimal or no meats. And they do it day in and day out. This does not mean you can’t have the occasional treat, like say a large pepperoni NY Pizza! Just don’t live off the stuff. And only eat what you need. Take home boxes and left over’s good too.

Conclusion:

It is pretty simple to see. First, you must see the need to change; your style of food consumption or exercise or perhaps both. Many may just have some room for improvement; others need a whole new approach.

Eat less and better. Exercise more. Live healthier, and dive longer!

I’d rather see you underwater than underground.

Regulators...what is the difference?

First Stages

(I would like to give a special thanks to my friends at SCUBAPRO for providing the illustrations...it is good to have friends!)

FIRST STAGES
The task of a first stage regulator is quite simple: reduce high pressure air coming from the tank to a consistent intermediate pressure. They are generally divided into PISTON and DIAPHRAGM categories, depending on the mechanism used to control the valve allowing air to flow to the second stage. Due to their design and their particular advantages, each of them has become the favorites of different groups in the diving community. First stages can be further classified between CLASSIC DOWNSTREAM and BALANCED, affecting function and performance of the first stage related to pressure changes in the tank.

THE PISTON TECHNOLOGY
The general advantage of a piston-based first stage lays in its reliability and reduced maintenance requirements, due to an effective but simpler mechanism with less moving parts. More importantly, no other design can reach the high air delivery rate of a balanced piston controlled first stage.

Balanced-piston first stages are the first choice of demanding deep sport divers and professionals. First stages with air balanced pistons deliver significantly more air to the second stage than any other first stage, while their performance is totally unaffected by changing tank pressure and depth. 

AIR BALANCED FLOW THROUGH PISTON
First stages with air balanced pistons deliver significantly more air to the second stage than any other first stage, while their performance is totally unaffected by the changing tank pressure. A balanced piston allows the use of lighter and more sensitive components, resulting in ultra fast breathing response, instant delivery of air on demand and extra high air flow, especially in low tank pressure ranges. The tired diver benefits from of a smoother breathing regulator during the ascent or deco stop. Balanced piston first stages are the first choice of demanding sport divers and professionals. A balanced piston performs equally in both warm and cold water environments.

CLASSIC DOWNSTREAM PISTON
This is the best example of bulletproof reliability and trouble-free, minimal maintenance regulators. The conventional downstream piston configuration is the simplest mechanism that exists to control the pressure drop from a tank to feed the 2nd stage. The classic downstream valve is the first choice of diving centers and rental facilities worldwide for warm and moderate water temperatures.

This is the best example of bulletproof reliability and trouble-free, minimal maintenance regulators. A classic downstream piston does not compensate for the minor changes in pressure delivered to the second stage as tank air is consumed, but still guarantees solid performance.

DIAPHRAGM TECHNOLOGY
Diaphragm based first stages are environmentally sealed so that water cannot enter the inner mechanism. Bearing in mind that regulators generate temperatures up to minus 30 °C due to the incredibly fast moving air and the high pressures involved, it is imperative that sensitive moving metal parts avoid contact with extremely cold water.
Therefore, diaphragm first stages have been the favored choice of cold-water divers and those working in contaminated or muddy water.
All SCUBAPRO diaphragm first stages feature a balanced technology and are packed with patented features resulting in ultra fast flow to the second stage upon request and a fantastic overall performance and are my personal favorite of the diaphragms. The balanced diaphragm technology provides consistent performance at all cylinder pressures, at any depth and optimizes the second stage performance, thus allowing for effortless breathing.

Diaphragm first stages featuring a dry balancing chamber so that the water cannot enter the first stage, means it's resistance to freezing is unmatched even in extremely cold waters.

Diaphragm first stages with the same structure but without a dry chamber are the perfect choice for the recreational diver who wants the advantage of a diaphragm first stage for use in temperate waters.

 ~More details below~

BALANCED DIAPHRAGM (Dry Chamber)

Diaphragm based first stages are more complex and have more moving parts than piston first stages. With a dry chamber, they have an environmentally sealed design so that water cannot enter the inner mechanism.

Diaphragm first stages have been the favored choice of cold-water divers because of their better resistance to freezing. They are also recommended for divers working in water containing a high degree of suspended particles, silt, or other contaminating materials.

BALANCED DIAPHRAGM

Diaphragm first stages have been the favored choice of cold-water divers because of their better resistance to freezing.

Diaphragm first stages are also recommended for those working in water containing a high degree of suspended particles, silt, or other contaminating materials.

Second Stages

A second stage regulator must translate natural breathing behavior into mechanical reality. A high quality second stage can significantly reduce stress and enhance diver safety by providing smooth, low-effort breathing response, resulting in ample yet controllable quantities of air. The designation "balanced" and "classic downstream" are also distinguishing marks for second stages and imply the same general attributes like first stages, i.e. ultimate flow performance and incredible inter-stage pressure stability in addition to reliability, simplicity and solid performance

AIR BALANCED VALVE TECHNOLOGY
The air balanced valve technology of SCUBAPRO second stages features a balancing chamber in the second stage mechanism, slightly offsetting the force of the downstream air entering from the first stage. This allows reduced spring tension and decreases the inhalation resistance to the lowest possible level. The result is an ultra-high airflow that remains exceptionally stable under all breathing conditions. The air-balanced valve technology is featured in our A700 and S600 second stages. For optimum results they should be combined with balanced first stages, like the MK25 or the MK17. These are the combonations Coleen and I dive. 

OPTIMAL FLOW DESIGN TECHNOLOGY (OFD)

The Optimal Flow Design valve is the ultimate evolution of the classic downstream technology. Unlike this one the OFD valve features a full length piston shaped to obtain the optimal aerodynamic performance. The gas flows freely over the piston surface and provides the diver with the best breathing experience. No regulator part slows down the airflow, and even the valve spring is shifted to the back side of the piston so that the air doesn't have to flow through the spring coils. The airflow is huge and rich but always under control. This is an intermediate worry free regulator with high end performance.

CLASSIC DOWNSTREAM TECHNOLOGY
Classic downstream valves are particularly noted for their legendary safety and reliability. When in use, the downstream valve opens in the same direction as the incoming airflow. To close the valve and stop the airflow, a spring counteracts the force of the incoming air. Therefore, a certain inhalation effort is always required to overcome the spring tension and open the valve. The classic downstream valve is a popular design for alternate air sources such as an octopus or AIR 2. Technical divers will often use a Classic downstream for stage bottles.

Barotrauma

Barotrauma of the Ear

Barotrauma in divers is physical damage to body tissues caused by a difference in pressure between a gas space inside the body, and the surrounding fluid.

Barotrauma typically occurs when the diver is exposed to a significant change in ambient pressure, such as during ascents or descents, or during uncontrolled decompression of a pressure vessel, (i.e. Chamber).

There are several types of barotraumas that affect divers, today we will look at Middle Ear Barotrauma or M.E.B.T. Understanding M.E.B.T. will give your good insight to the other types of barotraumas.

Divers may first incur the symptom of an “ear squeeze” prior to the actual barotraumas. Pain is never a good thing during diving… or really any other time.

  

Ear Function & Anatomy

It will be useful in understanding the subject to have an understanding of the basic function and anatomy of your ear.

On the side of your head you have a substantial bit of cartilage and skin commonly identified as “an ear”. This is actually the Auricle and can be fun to nibble on. The passage way going from the Auricle into your head is the External Auditory Meatus or ear canal. Next you run into the Tympanic Membrane or ear drum. On the inside of the Tympanic Membrane is the middle ear. The middle ear is an air space with three bones (Malleus, Incus & Stapes) connecting the Tympanic Membrane to the inner ear, and the opening to the Eustachian Tube. Next is the inner ear made up of the Cochlea and Semicircular Canals. (I left the Semicircular Canals off the diagram for simplicity.) These structures are filled with a liquid made up of nearly all water, and therefore uncompressible. There are two very important features on the Cochlea: The Round Window and the Oval Window. These windows are a flexible connective tissue. 

Sound waves enter via the Auricle, pass through the Canal and strike the Tympanic Membrane. The Membrane turns the waves into vibrations which are transmitted via the three bones into the liquid of the Cochlea via the Oval Window. The Auditor Nerve has sensors in the Semicircular Canals which transmit signals to your brain and you interpret the meaning of it all! But what happens to the vibrations in the Cochlea fluid? That energy must be dissipated somehow; the structural material making the Cochlea is very hard, un-giving skull bone. That is where the Round Window comes in. It absorbs the vibrations like a trampoline. The Round Window actually vibrates out into the middle ear space, transferring the energy into the air and displacing air and energy down the Eustachian Tube. There you have it. So simple I am sure it is an accident of nature.
If we simplify the whole thing, and straighten it out it would look something like this:

The “U” shape is filled with water, the center island and area surrounding the top, bottom and right side are bone. The missing Semicircular Canals would be represented attached to the top right section.

Barotrauma can affect the external, middle or inner ear. It is most common in the middle ear and is experienced by 10% - 30% of divers.

Causes

There is really only one mechanism of injury for the diver to consider: breathing gas in the middle ear or gases in the external ear becomes trapped and expands causing damage. This can occur on descent or ascent (reverse squeeze). The gas may become trapped a few different ways:

·      The Eustachian Tube is blocked. We see this most commonly when the diver has a cold or allergies. It can happen if the diver has used a sinus medicine or nasal spray to clear up his sinuses and the affects of the medicine wear off during the dive. This is one reason not to use such medicines. (Another reason is; some of these medicines are in the class of drugs known as Oxygen Exciters. Oxygen Exciters when used with ambient pressures somewhere more than 1 ATM can impede normal cognitive functions.): Yes, that is a sad face experience.

·     Middle ear infections can cause the middle ear space to fill with fluid and the exit to the Eustachian Tube to be blocked.

·     The Eustachian Tube can be compromised by infection or trauma.

·      A wetsuit hood or similar piece of SCUBA gear worn over the ear can cause an external Barotrauma rupturing the Tympanic Membrane. (Ouch!)  Wax can also cause a similar situation. There are those divers who use “ear beer” to clean out their ears before and after diving. I have never used it and have no recommendation. Except, don’t drink the concoction: 1/3 rubbing alcohol, 1/3 hydrogen peroxide, 1/3 white vinegar. It’s up to you!  

The Pathology

The pathology (a cool word for injury in this case) is normally tearing or rupturing of the Tympanic Membrane. Less often it is a similar trauma to the Round Window. It is almost never, or maybe even never, damage to the Oval Window. Even as pressure builds on the outside of the Tympanic Membrane pushing the three bones into the Oval Window, hydraulically transferring pressure via the Cochlea fluids onto the Round Window, causing it to tear or rupture before the Oval Window will. Which is a good thing; because it is a lot easier for the Round Window to heal vs. the Oval Window which would likely have the Stapes bone in the way now. Yes, another accident of nature.

Bottom Line

Be sure to dive only when your ears and sinuses are clear. If you have a chronic problem or are experiencing seasonally allergies, see a M.D. who is a diver him/herself and is well acquainted with dive medicine.

While performing descents or ascents if you feel some pressure or discomfort in your ears: Stop, reverse direction until the pressure or discomfort goes away, begin your equalization process and then continue on.

Be smart and live to dive another day my friends. 

Creating Ideal Buoyancy

Creating Ideal Buoyancy

The idea of Ideal Buoyancy is one not commonly understood very well. Too many divers, of all certification levels, act as if staying off the bottom and under the top equates to good buoyancy. If you feel that way ... read on!

Ideal buoyancy is characterized by a diver who moments after he takes a normal SCUBA breath  rises a bit in the water column. Moments after exhaling, he descends back to where he was. The idea that a "neutrally" buoyant diver stays in the same place is not only wrong, it also makes it very difficult to learn ideal buoyancy. In fact, let's dispel the idea of "Neutral Buoyancy" and take it out of our vocabulary altogether. 

A diver with "Ideal Buoyancy" does move up and down in the water. Period! An object with neutral buoyancy cannot have expanding gasses in it without a fluid or dynamic counter balance. The fact that we breathe gas that expands in our air ways, and then exhale it means, that in a practical sense we will never be neutrally buoyant. So why try to get there? 

If you could diagram a diver swimming with ideal buoyancy his path would look like a gentle sine wave. With each crest being proceeded by an exhalation and each valley being preceded by an inhalation. Something like this:

The delay from breath to crest or valley is the time it takes for the new buoyancy force to have effect.

So how do you get there? It is really pretty easy.

Here is what you will need:

• An empty (500 PSI or where ever you would normally end your dive) SCUBA cylinder. The same size and make up you will be diving with. i.e. an aluminium 80 or maybe a steel 72.
• Your full SCUBA  kit that you will be wearing while diving.
• Water...not to drink, the water you will be diving in. The depth does not need to be much deeper than you are tall. Remember a salt water pool does not normally have the same salinity at the oceans and seas.
• Weights: preferably including several one and two pound weights.
• Integrated weight pockets.  (If you own a weight belt, please use it for something other than SCUBA diving.)
• A dive buddy in full gear, including an alternate air source and a full tank of air.

The Process

1) Getting the correct amount of weight.

But first "The Incident":

Find your water; put on your full kit EXCEPT your weights. Here is why. I was at a popular certification site doing some OWD certifications on May 4th and 5th this year. This is a fresh water site with about a 90' bottom and vertical rock sides. A student from another dive center was apparently drastically over weighted.  In retrospect, I can see the instructor did not have control of his class and she was NOT in his sight.  She went to the bottom. I mean out of control decent! She later said she thought she was drowning. She spit out her regulator at depth, dumped her weights, inflated her BC and kicked like a dolphin! I first spotted her at about 30 feet. She passed 20 feet away from me at 15' of depth looking like a Trident Missile! The short version is: I did a solo surface rescue. (No, her shop personnel did not realize she had gone missing.) She had frothy blood from her mouth and nose, was bleeding out of her eye sockets and had the appearance of rather remarkable facial subcutaneous emphysema. She was conscious, allowing me to gather quite a bit of information from her as the paramedics arrived. Bottom line for us: No accidents! Therefore:

• Buddy in the water before you, with a full tank of air, alternate air source(s) and a fully inflated B.C.D.
• Shallow water is better than deep
• Fully inflate your B.C D. prior to entering the water
• Regulator in your mouth
• Enter the water
• Start without weights

Come out in the water to your buddy and have him/her get a good grip on your vest. When you are ready, hold your breath and slowly let the air out of your B.C.D. You should float like a cork as you are not wearing weights. Now let your breath out. You most likely will still be a cork. But you may not. Now return to the water's edge and add 1 to 2 lbs to your weight pockets. Make sure there is an equal amount of weight in each pocket. (I will cover weight distribution a bit later.)

Repeat this process until you float about eye level in the water with a full breath of air, and when you let your air out you barley sink. Now you have the correct amount of weight for the end of your dive. This means, with a full tank, you should gently sink. An aluminum 80 at the end of a dive will give you somewhere around 4 lbs of positive buoyancy or upward lift depending on the amount of breathing gas left in it. Which means the same tank, with a full load of breathing gas will give you about 4 lbs of negative buoyancy, when compared to the "empty" tank at the end of a dive.  Don't forget that! I actually lighten up a bit from there so I need to swim myself down two or three feet before I sink. In any case the "sinking" should be slow and EASILY controlled.  

Also, you do not want to be so light at the end of the dive you are struggling to stay at a safety stop or are not 100% in control of your entire accent. When it comes to weighting, "practice makes perfect".

2) Ideal weight distribution.

When determining your proper weighting, you were in an upright position and floating comfortably on the surface. This is less than an ideal position for diving. Have you ever noticed divers swimming past whose heads are higher in the water column than their feet? They resemble an air plane in take off! Humm. Why is that? Typically what you are looking at is the cool stuff underneath you, not so much in front and above you. Your most natural ergonomic posture is essentially a comfortable upright, standing posture. Now put on your imagining caps and rotate that position to prone. Yep, just like lying down on a massage table. ... Nice thought! That is the position of ideal buoyancy. Maybe, we should call it the "massage position"? ... Maybe not. 

Weight distribution is how we get there. Trim weights is the term commonly used. 

Your body mass, adipose (that is a nice word for fat if you are unsure!) and muscle distribution combined with your equipment will determine how much weight to trim with and where to place the trim weight. The best part? It is not hard to do. But it is very individual. Let me try to give you some ideas. 

I use three different B.C.D.s: A ScubaPro Knight Hawk when I teach, a Dive Rite Trans Pac with a wing for most of my dive trips and a back plate and wing for my doubles. I use two tank bands on my wing rigs. My Knight Hawk has trim pockets located in between the bladder and the back of my shoulders. I am also fairly solid at 5' 10" and 185 lbs. My shoulders are about 42" and my waist about 33". Plus I my mother often told me I have rocks in my head. 

My darling wife on the other hand is 5' 2".  She is rather curvy (narrow waist with an hour glass figure topped of with ... yes, a pretty good size bust.) She has also been very athletic and has a solid build. See Coleen on the Gobe Dive Shutterfly Site*

Coleen

Coleen and Ebby

Is there any reason to think our trim weights would be in the same places or in the same percentages of the whole? Uh, no.

 The last factor acting like a variable is the wet suite/exposure protection. I weight my Nova Scotia different than a dive skin.

Generally speaking I put about 80% of the weights in pockets on my hips and 20% on the lower tank band. Don't forget, you can always add a tank band for the purpose of adding weight pockets for your trim weights.

Coleen on the other hand, puts about 50% of her weight on her hips and 50% on her upper tank band to compensate for the adipose in her chest. (Wasn't that a tactful way of putting it?)

I have seen other divers use the same ankle weights that dry suite divers commonly use. These weights can be added on to nearly any part of you gear.

By way of caution it is useful to remember trim weights are not easily removed while in your gear. 

Whatever combination works for you be absolutely symmetrical. If you find yourself twisting in the water, your weights are the likely suspects.

The Result

The result of ideal weighting is relaxation. You are not fighting to stay in the proper position, twisting, staying at your desired depth, or filling your B.C.D. with air at depth. You will also notice you can adjust your depth with merely breath control. This goes a long way to become a "Zen" diver. 

The bonuses: One, you are more relaxed and having a better, safer time. Two, your gas consumption rate goes down. That's good stuff right there!

 

                

Coleen

Lance

*GOBE Shutterfly https://gobedivers.shutterfly.com/