The Dive Computer, an Essential Item You Should Own

The recreational dive computer has allowed divers to extend their diving as well as giving a better means to prevent DCI. The development and publishing of the recreational dive tables was one of the first steps that increased the safety of divers. These tables were a modification of the tables that the U.S. Navy had developed for their divers. For the recreational diver, the Navy tables had some fundamental even fatal flaws. Navy divers normally worked at one depth, they descend, do the job and return to the surface. The No-Decompression Limits (NDL) were easy to follow for them. Recreational diver are more likely to spend time at different depths while diving. So following the NDL left the potential of unused diving time. On the other side of the coin, the Navy tables accepted a higher degree of risk than a recreational diver could be expected to accept. Navy divers would follow the same tables in times of war, were mission requirements were higher. The Navy divers also has rapid access to doctors knowledgeable in dive medicine and a better network of decompression chambers. The recreational tables used the same science, however, they assume a smaller number of acceptable DCS cases.

The Navy developed the dive tables primarily because their first attempts to make a mechanical device were too unreliable. Devices were designed in the early 1950s, but it was not until 1984, that the Navy had a device that was somewhat dependable. Still, they used the tables for planning. The concept of multiple level diving and the advancement of electronics brought in the early dive computers. As technology advanced and prices stabilized they became an acceptable tool for the recreational diver. We now teach you on your open water course how to us a dive computer on all of your training dives.

Why you should use a Dive Computer

The recreation dive tables, now in use, took decades of study to develop and they have been a great tool to reduce the incidents of decompression sickness (DCS). However, they are based on a concept of a steady descent, diving at one depth and a steady consistent return to the surface. Divers seldom dive that way. We might drop down to a wreck, explore it at the bottom, then come up five meters and explore the bridge. Maybe we will follow the contours of a reef, sometime going shallower than others. The point is we are not stationary and our depths changes. A dive computer is measuring our depths and times, then it calculates our remaining NDL times. If we go slightly deeper than the depth we planned with our dive tables, the dive computer will tell you how much NDL time you have. No guess work. It is also a constant reminder, every time we look at our gauges, it is right there reminding us how much time we have left with our dive. There is also a visual display that shows how close you are to the maximum safe level of nitrogen in your system. Another item not mention as much is the calculation of the surface interval. The dive computer will still be operating in the background keeping track of your off gassing. So when you start your next dive, the nitrogen in your system is already account for.

Many dive computer allow different user profiles. A diver that has one or more risk factors for DCS, can select a more conservative evaluation of his dive. This takes some the guesswork out of the planning.

Technical boring stuff

The science behind the functioning of a dive computer and the algorithms they use are very complicated. This explanation will give you some insight into how a dive computer works, however, it is oversimplified. The body absorbs nitrogen while under pressure, however, the rate of that absorption varies greatly between the different types of muscles and other tissues. Certain tissue will absorb the nitrogen much faster than others and will reach a saturation point where no other nitrogen can be absorbed in a faster time. The amount of nitrogen that can be absorbed is a factor of the pressure. This ability to absorb or release nitrogen is expressed in a half life in minutes. In your chemistry classes you learned that radioactive isotopes lose 50% of their radioactivity each half life. A similar concept is used in dive computers were each tissue will lose ½ of its nitrogen load over a certain period. The algorithms group the body structures into groups with the same half life. Many of the dive computer manufacturers use 10 groups that can be called tissues or compartments. Mares a leading manufacture has the following half times in minutes: 2.5, 5, 10, 20, 30, 40, 60, 80, 120 and 240.

As we start our dive, the computer calculated the time and pressure of the dive and applies that information to the compartments. This means that the dive computer has calculated the percent of saturation for each of the compartments. The algorithms are programmed with a maximum ascent rate and a percent of saturation, expressed in partial pressure of nitrogen, that is considered safe. To calculate a NDL time, the computer looks at all compartments, determines the amount of off gassing done while returning to the surface. It then tells the diver the remaining time for the compartment that will have the highest saturation upon returning to the surface. The same process of using algorithms were done to create the current recreational dive tables.

Why should own your dive computer and not rent?

The proper use of a dive computer can lead to safer diving. While dive computers are easy to use, each model has different features and may present the data in a different manner. You need to fully understand the operating manual for such a critical safety device. Getting a rental is better than none, but unless you have used it before, you are not getting its full benefits. Most liveaboard dive vessels require the use of a dive computer on all dives. Some dive centers have also adopted that requirement, as has a number of locations. Training agencies are reducing the reliance on dive tables and are focusing on computers. It may not be long before they will be mandatory. The price of a recreational dive computer that will also allow you to dive with nitrox is reasonable. The purchase price verses renting one can be recovered within a few rentals. If you are taking a dive vacation, you will likely be able to purchase one for less than the rentals.

Dive computers will store the dive information and recent computers will allow you to export the data and integrate it with your dive logs. You can have a visual representation of your dive depth and times for later reference. This is a feature not frequently available to you will a rental.

The dive computer has proven itself for many years. You will see few experienced divers, diving without one. While technology advances, the dive computer available for purchase will not be obsolete anytime soon. The core functions, the calculations that make you safe, are proven solid. An investment today, means you will recover that investment sooner.

Decompression Illness

Knowledge is your Best Protection

hey say that for every Ying there is a Yang, For every good there is a bad. For scuba diving the bad is Decompression illness, or DCI. To quote the Diver Alert Network (DAN), the largest organization focused on dive medicine,

“DCI encompasses two diseases, decompression sickness (DCS) and arterial gas embolism (AGE). DCS is thought to result from bubbles growing in tissue and causing local damage. While AGE results from bubbles entering the lung circulation, traveling through the arteries and causing tissue damage at a distance by blocking blood flow at the small vessel level.”

While there are similarities between the two, it best to remember DCS relates to tissue and AGE to blood supply.

In the early day of diving, before we learned about the effects of gases under pressure on a divers body, DCI caused many deaths and gave scuba diving the notoriety of being a deadly thrill. It is not really an accurate statement saying the effects were unknown, it is more accurate to say they were not understood, not by medical personnel and clearly not by divers.

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Decompression Sickness, What is it and how to avoid it

In your open water training, you review the basic principles of three laws of chemistry, they are Boyle’s, Charles’s and Henry’s laws. Elements of these laws will help to explain how gases under pressure react within our bodies. In 1662, a physicist and chemist named Robert Boyle proved a theory that volume and pressure were inversely proportional. We learned Boyle’s law in science whereas when pressure increases volume decreases. This principal is not only important for us to understand for DCS avoidance but also impacts how long a tank of air will last. Boyle also believed that nitrogen under pressure would be introduced into our blood stream in larger amounts and forced into tissue. Henry’s Law in 1803 proved that Boyle was right. It also showed two important concepts. Increased pressure also increased the solubility of blood to carry nitrogen, and the tissue would try to balance the present of nitrogen in the lungs. Boyle also stated that if the nitrogen was not able to escape the tissue, it could cause physical damage. As we descend the partial pressure of nitrogen we breath goes up, as well at the blood’s ability to carry it. So the tissues start loading nitrogen. When we ascend, the partial pressure is now higher in the tissue, so it will start exciting the tissue. However, the blood solubility for nitrogen has been reduced so there is a delay leaving the tissue. Think of it as a three lane highway going in but just a one lane coming out. If you give it enough time, it will get out. DCS is medically classified into two types, type I which is pain only, and type II which covers the rest.

In the late 1800’s, workers building the Eads Bridge (St. Louis) and the Brooklyn Bridge (New York City) were becoming ill and many of them died from the illness. The bridges were being built using caissons. These are metal devices with an air lock at the top and open at the bottom. They were placed on the river bed and filled with compresses air to pump the water out. The pressure was maintained to keep the water out. Workers would enter the device’s airlock, travel to the bottom to work digging and placing the foundations and anchors for the bridges. When they returned to the surface, many of them became ill within minutes. The illness became known as Caissons Disease, which we now know as Decompression Sickness. DCS can be slow in its appearance. Most cases appear between 5 minutes and six hours after a dive, a small percentage up to 12 hours and even smaller percentage as long as 48 hours. Flying or going to a higher elevation can also bring on DCS if excessive nitrogen remain in your tissue. Divers are advised to wait 24 hours before flying. Symptoms of DCS which the workers also endure are (these are things you feel):

• Unusual fatigue
• Skin itch
• Pain in joints and / or muscles of the arms, legs or torso
• Dizziness, vertigo, ringing in the ears
• Numbness, tingling and paralysis
• Shortness of breath

Signs of DCS (Item that are noticeable):

• Skin may show a blotchy rash
• Paralysis, muscle weakness
• Difficulty urinating
• Confusion, personality changes, bizarre behavior
• Amnesia,
• tremors
• Staggering
• Coughing up bloody, frothy sputum
• Collapse or unconsciousness

It did not take long before all workers suffer to some degree from DCS. It was noticed that the symptoms became milder or disappeared entirely while the worker was deep in the caissons. In the medical studies it was found that if they brought workers up slowly, fewer became ill, even less if they stopped for a few minutes on the way up. These doctors for the bridge building company’s were the first to bring light to the concept that we use for maximum assent rate and the principals of decompression diving. On a light note, the situation with the workers lead to the development of the term bends. In scuba slang we will hear someone say, “they got bent” or “be careful of the bends”. Technically this applies to type I DCS. For the caisson workers, within a few minutes most were bent over in some degree of pain after their work shift ending. At the time there was an upper class fashion called the Grecian Bends. The body position of the men in pain from their work was very similar to the body position of women wearing the Grecian Bends style. So the term was also applied to the workers.

These early studies were expanded upon by the US Navy and the U.S. Navy dive tables were developed. Using a maximum rate of assent as a part of the calculations, the dive tables gave some guidance how long a diver could stay down and avoid DCS. This is the science behind all the dive tables, dive computers and warnings you receive.

In your open water training, you will learn or did learn the principals of avoiding DCS. They include how to read the dive tables and use them to plan your dives. Also, included will be the safe rate of ascent and the practice of a 3 minute stop at 5 meters for extra safety. Currently, the use of the dive tables is not as frequent as it once was after training. Dive tables are based on diving to a specified depth and the calculations are based on that. Technology in the form of dive computers can read current depth and time then use formulas to give a real time evaluation based on your dive. Still, having a good understanding of dive tables are a good foundation to manage your risk.

Unexplained DCS

DCS does have another dark side, even if you follow all the rules, you still can get DCS. It is known that certain factors can increase the risk of DCS. Certain drugs, a hangover, being overweight and dehydration are just some the known factors that might make someone more likely to become a victim. Even setting those factors aside, some people get it anyway. The percentage is small but still there.

Treatment

If you have any concern that you or a fellow diver is being effected by DCI you need to seek medical attention. As an immediate first aid, administer 100% oxygen. This may be enough to slow the progression and maybe even stop it. Then get evaluated by a medical professional knowledgeable of dive medicine. A decompression chamber is used to treat DCI, it brings a patient to a condition under pressure and slowly brings them back to surface conditions. Prompt treatment may result in no lasting complications.

Arterial Gas Embolism (AGE)

The second member of the Decompression illness classification is the Arterial Gas Embolism. AGE happens when bubble in the blood stream blocks the flow of blood, a bubble larger than the capillary vessel. The lack of blood can cause tissue damage. As the brain is one of the largest users of blood, it is the one organ most at risk. AGE can cause strokes and create brain damage. The percent of AGE cases only make up about 7% of the DCI cases. As bad as that sounds there is one thing to remember, AGE is almost 100% preventable. When you breathe, the lungs diffuses gas into the blood stream. Large molecules are blocked. AGE is caused by a Pulmonary Expansion barotrauma. This happens when you hold your breath during ascent. The air in your lungs expand as the gas does. However, when it reaches its limit it will burst, just like adding air to a balloon eventually it will burst. This rupture in the lung will allow air to pass directly into the blood stream without the larger molecules being blocked. In some rare cases AGE has occurred on seemly normal ascents. These cases have mostly been linked to preexisting heart or lung conditions.

Symptoms of AGE

• Dizziness
• Visual blurring
• Areas of decreased sensation
• Chest pain
• Disorientation

Signs of AGE

• Bloody froth from mouth or nose
• Paralysis or weakness
• Convulsions
• Unconsciousness
• Cessation of breathing
• Death

Many of the signs and Symptoms of AGE are similar to DCS type II, and the first aid for them are the same. Administer 100% oxygen, make comfortable and seek medical attention immediately. AGE symptoms appear rapidly and escalate fast. Unlike DCS which seldom has symptoms underwater, death due to AGE can happen before the diver can reach the surface.

Insurance

There is an old joke against the medical field, it says the leading cause of heart attacks after surgery is seeing the hospital bill. The best means to avoid this is to have good medical insurance. Even if you have medical insurance, consider getting dive medical insurance. Dive insurance companies generally have agreements in place with decompression chambers where the chambers will accept the insurance. Most insurance companies do not and if not, you will need to made a deposit before treatment is started. Deposits can range from $5,000 to 25,000 cash. Best to think ahead.

Diving’s Worst Case

When you take your Open Water Diver training, most of the knowledge section and many of the skills relate to DCI and how to avoid it. It is these skills that you will practice and master that makes DCI a managed risk. Forty years ago if you became a certified scuba diver your life insurance company would cancel your policy. Some policies would have a higher premium for divers and exclude any benefits for deaths that happened elated to diving. Times have changed, today diving is considered safer than horseback riding, and you have a greater chance of being injured on a golf course than getting a DCI. This is due to the training and you understanding of the risk.

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How to Improve Your Style and Dive Longer

 Your Style and Dive Longer

 Have you every watched a shark as it moves along the reef? You see its smooth almost majestic movements, the   stream line body, and the relaxed manner it moves into a school of fish. You know that it has power and great   speed, however, the shark only calls on it when needed. The shark has evolved to be efficient under the water,   scuba divers have not. We have to work at it. The way we move through the water greatly impacts the energy we   spend and the air we consume. It is a skill that takes time and conscious effort to learn and sadly many divers do   not even try. Often, it is a case that we do not know how bad we really are, it takes someone to tell us or show us.

What is a proper form

The proper form will keep you moving in a stream line manner, much like your favorite shark. Your body from the head to your knees should form a straight line. Your head should be forward facing and you knee bent to a 90° angle. This may sound easy but it does take a little work. When you first start working on your form, do not concern yourself too much that you are not horizontal. The position of your weights will affect the horizontal position. Once you have the form proper or at least close, you can adjust the weight trim.

Most people have poor posture, no matter how many times our mother told us to stand up straight. We will find that our muscles have remembered those positions we normally use. When we float, the body will relax but may not necessarily form the position we need. Many will find their natural position is with the rump up higher than the spine. This forces the legs down, now when we kick we are forcing our selves up as well as forward. The best way to correct this is to arch your back slightly, square your shoulders and stretch your chest. This is the form you will see parachutist take in free fall.

Your knees should be bent so that your calves are slightly above your back and the ankle relaxed allowing the blade of the fins to be parallel with your body. Your hands are not a part of your propulsion underwater. They should be held in a stream line position if they are not in use such as holding a gauge or a light. Many divers will hold the arms in front of them, one hand lightly grasping the other wrist. Arms at your side or folded across your chest are also popular means to stay stream line.

I became certified at a local dive center near where I was living for a year. After becoming certified, many of my dives were with my instructor as the dive master. We would spend our 5 meter safety stop working on my and my dive buddies form. The instructor gently controlling our body positions to help create a muscle memory. That is something you and your buddy can do.

Using weights to adjust your trim

The article on buoyancy control briefly mentioned trim. Your body has a center of gravity (COG), a pivot point if you will. Like a seesaw you want to keep the weight on ether side in balance. The further away from the center of gravity the greater the impact weight will have. While the location of your dive weights are important, it has to be used in conjunction with other items. The cylinder is often overlooked as an element of trim. It’s position can matter a great deal as it is on both sides of your COG. If you find your trim changes between your first and second dive, the location of your tank may be the cause. Most BCD’s have an adjustable loop that fits over the neck of a dive cylinder. You can use that strap as a guide to position your tank each time. When you find the proper position for your tank, tighten the loop. Each time you place your BCD on a cylinder slide the BCD down until the loop is tight before securing the dive band. Many times divers will let the boat crew change over the equipment and they may not be as detail orientated as you should be.

The balance of the cylinder impacts your trim, however, as you start working on your trim its balance is less important than it being consistent. Some BCD’s have shoulder pockets for trim weights, weights added here will reduce a positive trim, one where your chest is higher than the COG. If your BCD does not have a shoulder pocket, you can purchase weights that will clip to your d-rings. Divers can place some weight on the tank or tank band. Weight added near the neck of a tank will bring the chest down and legs up. Weights near the tank boot will have the opposite effect. As you move weights to different locations, remember that you must maintain enough weight on your weight belt or other quick release to gain positive buoyancy in an emergency. You should also account for heavy gear. If you have a large dive light clipped to your BCD, not bringing it on a dive might affect your trim.

Streamlining your equipment is an important point. Like the streamlining you do with your hands, anything outside your body profile will cause drag, that will affect your profile. Keep hoses and gauges close to the body.

Do a five meter equipment check

As a part of each of my dive plans, I add a stop at five meters both on descent and ascent. Before you start your descent, you should make a check on your equipment. During decent, pause at five meters, become horizontal, check your trim and adjust your equipment if needed. On boat dives, the entry may have slightly moved your weights, and you might not notice it on the surface. After some practice, this stop will likely only take a few seconds. Check with your dive buddy and continue your decent.

Screen test

Thanks to the wide spread use of sports cameras, underwater video is not as expensive as it once was. The quality will not be the best, still it is good enough to share your passion. Instead of taking selfies underwater, occasional ask your dive buddy to take some video including you when you are not aware they are recording you. Examine the video and evaluate your form. Visualize doing it better next time.

 My most memorable dive was my 30th dive, about 18 years ago. It was my first dive in the Bahamas, and the first   dive where we were told to expect a number of sharks. It was also the first time where there was someone   recording   the dive. Back then video cameras were very large and very expensive. I spent a good portion of the   dive watching   the sharks, watching how smooth they were. After the dive, the dive master complimented me on   my form. When I   watched the video that was taken, I was pleasantly surprised, even proud, how good I looked   underwater. It also   showed me how most of the divers, even the experienced ones, took no care of their form.

Bad habits are hard to break

 It is best to start applying these skills, when you are first learning to dive. This gets you on the right path to having   great form before bad habits create a muscle memory. When that happens, it becomes more difficult to get the   proper form. When you were in school, your gym coach was always preaching about form and basic skills. The b   same principles apply in this sport as well. A bit of a conscious effort as a new diver and periodically checking   yourself as your diving continues will keep you in good form. A good form means less work, which results in   longer dive times and less fatigue after a dive. The knowledge you gain controlling your buoyancy also reduces   your risk of an uncontrolled ascent.

A little early work for a long time benefit.

 Learning what it takes for you to have a proper trim, excellent buoyancy and a good form will take a little effort at   first. A few minutes a dive working on it, will go along way to mastering it. Once it is mastered, everyone watching   the underwater videos will see you as the role model. The diver to follow.

 Improve you style with the Peak Performance Buoyancy course 

Richard Branson Expiration of Beleze’s Blue Hole

With the historic scientific expedition to Belize’s Blue Hole fast approaching, Aquatica Submarines has announced Discovery Inc. as the Expedition media partner. Discovery will be conducting a live broadcast of the Expedition, which will be televised globally from 4pm-6pm EST on Sunday, December 2ndthrough the Discovery Channel. The live broadcast will profile the Expedition team and follow them from the surface to the bottom of the Blue Hole. Aquatica’s Chief Pilot and Oceanographer, Erika Bergman, will be joined by Sir Richard Branson and Fabien Cousteau for this unique and truly historic event. As they descend into the Blue Hole, there will be a discussion included on the live broadcast about ocean conservation and preservation. These topics are a key focus of the Expedition for all parties involved, and the live broadcast will help ensure that this vital message reaches viewers around the globe.

Lamai Scuba Diving updated Website

We have updated our website still a few things to do but its up and running.

“I CAN SEE CLEARLY NOW”

HOW TO SELECT YOUR SCUBA MASK AND PREVENT FOGGING

DIVING IS ALL ABOUT SEEING and exploring the underwater world. Most people experience this unique setting only by viewing it on a screen, but as divers, the mask serves as our portal to a first-person experience of the aquatic realm. The scuba mask is typically constructed of a flexible material, such as silicone, and designed to fit the face, including the eyes and nose. The  scuba mask is designed with a skirt that seals the mask to the face to keep water out and provide an air space so the eyes can focus underwater. It has a tempered glass lens (or lenses) for viewing. One drawback of the mask is its tendency to fog. In this article we’ll examine how to select, prepare and care for the scuba mask, including how to keep it fog-free and clear it easily while diving.
When it comes to securing your very own window to the underwater world, the best place to shop for a good quality, well-fitting mask is your local dive center. There are subtle nuances to selecting the ideal mask and the pros at your dive center are trained to assist. The staff will explain how to test for a proper fit, how to adjust the strap and why being able to access the nose pocket with your thumb and forefinger is important. They’ll likely have a wide selection of masks from which to choose and, in some instances, they may have samples you can test in a pool.
Low-profile masks provide a wider field of view and make skills like mask clearing and equalizing a bit easier to perform. Some standard masks give a wider field of view due to clear side windows, which increase peripheral vision. Other options include masks with clear silicone skirts creating an open feeling. Dark colored skirts are also popular, especially with underwater photographers, because they tend to shade the eyes and reduce ambient light. Mask frames and skirts come in a wide variety of shapes and colors, such as white, blue, yellow and purple.
For eyeglass wearers, some masks can be quickly and easily outfitted with corrective lenses that match your prescription.
Some new mask styles offer special features like lenses with underwater color correction and UVA/UVB (ultraviolet A and B) filtering to protect your eyes from harsh sunlight.

Preparing Your Mask for Diving

Once you’ve selected a new mask, read the manufacturer’s instructions for pre-use cleaning. Some masks have lenses that are treated with a special anti-fog coating and don’t require any special cleansing prior to first use. In fact, aggressive cleaning techniques on treated masks can damage the defog treatment. Mask lenses that aren’t treated with a special defog coating should be scrubbed with a very mild abrasive cleanser and rinsed well before use.
Commercial mask cleaners introduced in the past few years are very efficient. However, there are some home remedies that also work well. One of the best cleansers is non-whitening, non-gel toothpaste. Before applying toothpaste to the lenses, wash your hands to remove any oil from your skin as natural body oils and cosmetic oils such as sunscreen lotions will negate the effects of the defogger. Now spread the toothpaste over the entire lens and skirt (inside the mask) with your finger or a soft-bristled brush. Rub thoroughly, then rinse well.
Some people swear by using fire instead of water to prepare the mask for its initial use, suggesting that you remove the coating by burning it off — heating the inside surface of the lens with a lighter. We do not recommend this technique, as you could easily warp or melt the mask’s silicone skirt and you risk injuring yourself in the process.

Keeping Your Mask Fog-Free

Masks tend to fog when moisture forms inside and condenses on the lens. As we mentioned previously, mask fogging can be a common problem, but it’s one that has several simple solutions. Defogging solutions work as surfactants that coat the lens prevent fog from forming.
Although you have completed the initial pre-use cleansing of your mask, you will likely need to use a defogging solution prior to each dive, although recently, defogging solutions have been introduced that are reported to last for an entire day of diving. Numerous commercial products are available in spray bottles, as gels, drops or paste. Some products are rubbed on the lenses and left to dry. Prior to the dive, the lenses are buffed until clean. Ways to defog your mask are definitely improving, making a lot of divers very happy. Of course, there are always the old standbys, which included diluted baby shampoo and saliva.

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Rare shark nursery discovered - SeaRover 2018

Wreck & Koh Tao 2 Dives

Description

HTMS Sattakut is located on the west side of Koh Tao is a purpose sinken wreck. It was donated by the Thai Royal Navy cleaned and stripped before a controlled sinking on June the 18th 2011. She lays just next to Hin Pee Wee dive site on a sandy area. The Stern is at 31 metres and the Bow at 26 metres pointing north to Hin Pee Wee. The shallowest part of the wreck is the wheel house at 18 metres.
As you dive around the wreck there are many port holes, looking though you can see a abundance of fish, Giant Groupers, Snappers, Trevally to mention a few. The bottom of the hull you can find Jankins Rays hiding out there. You will need you wreck dive specialty ito penetrate the wreck.
Diver Prerequisites
If you’re at least 15 years old and have PADI Adventure Diver Certification
Penetration of the Wreck
Wreck Specialty
After Wreck we have lunch. After lunch we do the last dive of the day at one of many amazing dive sites Koh Tao has to offer.
Duration: 1 Day, 2 Dives
Schedule:
Pick up from your hotel 7am for transfer to the pier were a light breakfast is provide. The speed boat leaves 8am and arrives  at the dive site  9.20am.
Lunch is served after the first dive, then after 1 hour surface interval we have the second dive.
We arrive back to the pier in Koh Samui 3pm
Include in the price
2 Scuba Dives
Hotel Transfers
Light Breakfast Tea/Coffee
Refreshments water/Soft Drinks
Lunch
Dive Equipment
Maximum 4 divers to per Dive Master
The cost of the tour is 5,000 Thai Baht per person
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We offer 10% Discount for early booking (10 days before the beginning of tour)

Homeowner Builds $2 Million Scuba Diving Pool In His Garden

Wouldn’t it be nice if you were rich enough to build your very own private pool deep enough to scuba dive?
Well, one homeowner in the U.S. state of Utah has done just that.
In addition to having a water slide, wading area, grotto and other amenities, the pool in Springville, Utahis 140ft/43m long, 60ft/18m wide and at certain points 26ft/8m deep.
The US$2 million pool — which holds about 360,000 gallons/1.4 million liters of water — was built so the avid scuba-diving owner could practice his skills without having to travel.
Animal Planet featured the pool in its “Pool Master” show (granted, it was a year ago, but it’s still really cool). Check the link below.
Scuba Pool

A second-stage regulator free-flow happens when the downstream valve in the second stage sticks wide open. Most of us have experienced that at one time or other at the surface. You place your regulator in the water at the surface with its mouthpiece face-up, and the next thing you know, your reg is wildly free-flowing. Usually, all you have to do is put your thumb or hand over the mouthpiece or turn the reg face-down, submerged in the water. At the surface, a free-flowing regulator is annoying, but at depth, a regulator locked in free-flow can be dangerous.

 Cold water is the No. 1 culprit behind a free-flowing regulator, but there are less-common reasons, too. For example, there have been instances of a diver using their octopus reg to inflate an SMB, only to have it free-flow. A second stage that is clogged with sand, jamming the valve open.
Suddenly, you’re immersed in more bubbles than those produced by a Jacuzzi. So what should you do if your regulator free flows at depth? You can continue to breathe from a free-flowing second stage as you surface, and during your open-water training, you practiced this skill. Follow our tips for dealing with it calmly and safely.
1) Remember your training. Invoke the mantra Stop, Think, Breathe, Act.
2) Remove the second stage from your mouth. Tilt the mouthpiece so that it’s partially in your mouth — grip it on the right side of your mouth as normal, but left the left side rest lightly on your lips, just outside of your mouth. (This allows excess air to escape through the sides of your mouth.)
3) Press the purge button and use your tongue as a splash guard against the roof of your mouth to prevent choking on water. Tilt your head to the right.
4) Keep your mouth slightly open and breathe carefully and calmly from the free-flowing air bubbling next to your mouth.
5) Ascend at a safe rate. A free-flow will deplete your air supply in a matter of minutes, so it's important that you surface as soon as possible.
6) Once you surface, close the cylinder valve to stop the free-flow.
7) Practice this skill in the pool. It’s not a great feeling to have your reg free-flow, but in the unlikely case it happens to you, it’s best to have practiced this skill. A pool is a safe environment for you to get comfortable with the skill.
Of course, there are other options:
1) If you carry a pony tank, switch to your bail-out gas, and then safely ascend.
2) Switch to your buddy’s alternate air source, and then surface together.
You know the old saying — an ounce of prevention is worth a pound of cure? That’s certainly the case with a free-flowing reg:
1) Make sure your reg is serviced regularly. Don't dive again with a reg that has experienced a problem until it’s been checked and repaired by a qualified technician.
2) When diving in cold water, get a cold-water regulator that’s designed to prevent free-flows.
3) Don't let your reg or alternate air source drag on the bottom or beach as it might get clogged with sand or mud.

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Underwater Navigator Specialty Course

We will also teach you 

Have you ever wonder how your instructor or Dive Master always find there way back to the boat or finds points of interest underwater. The Underwater Navigator course teachers you the skill and techniques to give you confidence to find your way around.

Academic

The Navigation course will teach you how to use the compass underwater using the bezel and the lubber line. To start with we make things easy by learning you with the cardinal points of north, south, east and west. For example if the north is in the 2 index marks on the bezel and you turn round till the south is in the 2 index markers you are on a receptacle heading.

• Methods to estimate distance underwater.
• Compass navigation while making at least five turns.
• Marking or relocating a submerged object or position from the surface.
• Underwater map making.

Equipment

Besides your basic scuba equipment, you’ll need a compass and underwater slate. Your PADI Instructor will show you how to use a reel and line for estimating distance underwater.
Diver Prerequisites

• Certified as PADI (junior) Open WaterDiver

Included in the price

• 4 Dives 3 Training dives and 1 fun dive
• This includes all your Padi materials required
• Transfer to and from hotel
• Light breakfast, , coffee or tea in the morning
• Refreshments
• Lunch
• Equipment

The cost of the Underwater Navigator course is only 11,000baht.
Maximum 2 to one Padi Instructor.
10% Discount for early booking (10 days before start of the course)

ReActivate Program

ReActivate Program program is designed to help you ease back in to the water if it’s been awhile since your last dive. Your PADI instructor will reacquaint you so you feel comfortable and relax diving again. You will update your dive knowledge, planning dives using the recreational dive planner , Problem management and skills. The pool or confined open water is where you will practice and fine tune your underwater skills with the guidance of a PADI professional.

A supervised open water dive is an optional addition to the program for certified divers. This dive offers an opportunity to obtain an environmental orientation to a local dive site from a PADI Member while gaining confidence and refreshing dive skills.
So what’s involved

• Practice open water skills
• Knowledge Reviews and a quick review
• Dive Planning using RDP and a Computer

We will also update your log book to show you are up to date on your dive skills.
Diver Prerequisites Minimum age is 10 years old, certified as PADI (Junior) Scuba Diver or above
Pool only 1,800baht
Trip to Koh Tao and two dives 6,000baht
Tao and two dives 6,000baht
ReActivate Program Include 
Hotel Transfer
Morning coffee/tea
Light Breakfast 
Lunch 
Refreshments 
Dive Equipment 
Divemaster  / Instructor
10% Discount for early booking only on the tour to Koh Tao (10 days before tour starts)

Sail Rock Scuba Diving Tour

Sail Rock is also considered a great dive site here in the Gulf of Thailand. It lies half way between Koh Phangan and Koh Tao. This is the place to see huge schools of fish like trevallies, bat fish, fusiliers, giant barracuda, bull sharks and the whale shark. There’s a swim though called the chimney which starts at 18mtr goes up to 5mtrs and a window at 12mtrs.

To the east side of Sail Rock there’s a pinnacle where you can see big shawls of Silver Trevallies, the pinnacle starts at 12mtrs and goes down to 34mtrs. The trip to Sail Rock takes about 50 minutes to get there and we return about 1.30pm.

We travel to Sail Rock everyday weather permitting

Visibility: 10 – 30 Meters

Currents: Mild to Strong

Experience: Intermediate to Advanced

Depth: 5 – 35 Meters

Scuba Diving Tours Include

• Hotel Transfer
• Morning coffee/tea light snack
• Lunch
• Drinks (water, soft drinks)
• Full Equipment
• PADI Divemaster/Instructor
• Total Cost 4500b
• 10% Discount for early booking (10 Days before start of Tour)

You have been looking forward to this coral reef dive. You take a giant step off the dive boat and find yourself in warm crystal clear tropical waters. Soon you start your descent. Around you there are beautiful tropical fish trying to figure out who is dropping in to see them. You are headed down to a splash of color that extends as far as you can see. You have seen fish like these before when you visited an aquarium, this time it is different. They are around you, no glass, it is their home. You see a turtle graciously moving below you, it seems not to have a care in the world. Welcome to the world of reef diving.

What is a Reef?

The majority of scuba divers prefer the warm tropical waters to do their diving and coral reefs are the primary focus of their diving. While there are cold water reefs, the warm water ones are the ones that gets our attention. Many Open Water Divers with their 60 feet/ 18 meter limitation look longingly at the deeper profiles of the advance open water and the deep diver. In reality, some of the best diving are in the waters that are in the realm of the Open Water Diver. Most species of coral rely on algae growth for its own growth and that algae requires sunlight. While a few coral species will grow as deep as 150 feet /45 meters and a few black corals as deep as 450 feet/ 135 meters, the majority are in less than 100 feet /30 meters. The largest concentrations are often in less than 60 feet/ 18 meters.
What we see as a reef, is a combination of living organisms and the skeleton remains of earlier ones. A living skin if you will. The reef foundation builders are the stony coral polyp. These creatures are very small averaging 1 mm /.04 inches to 3 mm /.11 inches. They are the simplest of creatures, a few layers of tissue, a mouth and tentacles. They, with the help of their algae which also gives them their color, excretes a calcium carbonate shell. They will live in this shell and retreat into it when stressed or threaten. To feed they extend themselves and open to the passing currents, using the tentacles to move food towards their mouths. A polyp in good conditions might create a second shell inside the first. Corals can reproduce asexually and sexually. When they reach a certain size they will create a bud, that becomes a separate coral which attaches and creates their own shell. Yearly, a coral colony will spawn. About 75% of the species will broadcast spawn, releasing male and/or female gametes into the water. These gametes are positively buoyant so they will float to the surface and hopefully combine. As they grow they will sink and hopefully attach to a suitable location. This event happens simultaneously over many colonies.
When the polyp dies the shell remains, and another polyp or coral larvae (planulae) may attach themselves and grow. Thousands of these polyps will form colonies. In time, larger species of coral will grow. The living portion of the reef is only a thin layer. NOAA Coral Reef Conservation Program (CRCP) has an interesting web page that gives a scientific explanation of coral reef development.

A few interesting facts about coral reefs can give us a better understanding of them. Even a small isolated reef will support a complex ecosystem. Coral reefs are the home of over 25% of the marine life in the world and over 35% will spend at least a portion of their life on the reefs. However, reefs cover only one quarter of one percent of the ocean floor. The majority of these reefs are found in three areas, the Coral Triangle, the Great Barrier Reef, and Mesoamerican reef systems.

Major Reef Systems

Most of the land mass around continents and islands in the tropical zones will have some form of coral formations. There are three forms of reefs: the barrier reef, the fringe reef, and the atoll. The barrier reefs are the ones we hear the most about, especially the two largest, the Great Barrier Reef of Australia and the Mesoamerican reef system. Both of these reef systems include a number of smaller barrier and fringe reefs. The Mesoamerican Reef includes the Belize barrier reef. A barrier reef is off shore from the land it is associated with. The face of the reef is on a continental edge which drops down thousands of feet. Behind the reef extending to shore is a shallower area called the lagoon. The reef helps protects the shore line which may be many miles/ kilometers away.
The main characteristic of a fringe reef is that it attaches or nearly attaches to land. The fringe does not have the continental edge that a barrier reef does and if it has a lagoon it is not very large. Any reef that you will dive from shore or near land will likely be a fringe reef. They are the most common of the reefs.
The Atoll is the least common form of a reef. According to Charles Darwin, the three forms of reefs are simply the different stage of development. In an atoll, the reef has formed an oval or circular formation around an island. Changes in seawater depth has caused the island to sink, leaving a ring of coral that is still growing. The inside of the ring is a shallow lagoon often with one opening to the open sea.
We have mentioned the two largest barrier reefs, the Coral Triangle area is the third large concentration of coral. The Coral Triangle represents an area with the greatest bio-diversity in the world. Quoting the World Wide Fund For Nature,
“The Coral Triangle, the global centre of marine biodiversity, is a 6 million km2 area spanning Indonesia, Malaysia, the Philippines, Papua New Guinea, Timor Leste and the Solomon Islands. Within this nursery of the seas live 76% of the world’s coral species, 6 of the world’s 7 marine turtle species, and at least 2,228 reef fish species.”
These three area contain the majority of the world’s corals.

Artificial Reefs

There is one more form of reef that does not fit the scientific view and that is the artificial reef. Since man has first started going to sea, boats have been sunk. When sitting on the bottom, they attract different marine life who rapidly move in. Seaweed, algae and other marine life floating in the current may also find these ship wrecks. Coral larvae may also take roots here and start the growth of a colony. It may take decades before the coral colonies are large enough to support juvenile fish with places to hid, however, the ship can provide that service. In time the ship wreck will be covered with coral and present the diver with an excellent blend of mankind and nature.
Many advocates of artificial reefs will point out there is nothing artificial about them. Man may have placed the substrate in the location, but it was nature that built the reef.

Reefs Need Help

It is a very sad point that mankind has done much to destroy the reef and marine life. Roughly one-quarter of coral reefs worldwide are already considered damaged beyond repair, with another two-thirds under serious threat. As we lose reefs, we also lose the breeding grounds for adults and sanctuaries for juvenile fish. As a diver, we need to make sure that our actions are not adding to the problem. Once a diver see a healthy reef and compares it to a damaged one, they can see the impact. Learn what you can about marine and coral conservation and do your part, however humble, to help turn this problem around.
Continue reading more from the DeeperBlue.com Beginners Guide to Scuba Diving.

Specialties and Advance Open Water Diving Certification

After you have your Open Water Diver certification complete, you will often have divers tell you what training you should take next. The amount of advice you get may be overwhelming. The first suggestion will be to take the Advance Open Water Diver (PADI) training or Advance Adventure Diver Training (SSI). This advice is well meaning and for many divers a good plan for additional training. As a OWD, you are certified to dive to the depth 60 feet/ 18 meters. As long as you are comfortable staying within that depth limitation, there is no requirement for additional training. While there are dozens of specialty programs, hundreds if you include PADI’s distinctive specialty courses, only a few are mandatory before recreational divers can dive in that area. Here are the mandatory programs and why they are:

• Advance Open Water Diver (AOWD): The primary outcome of this training program is that it changes the maximum depth that a diver can dive. Advance Open Water Divers are able to dive to 100 feet 30 meters. Advance Adventure Diver Training (SSI) is equivalent is PADI’s AOWD. SSI has additional requirements for their AOWD.
• Deep Diver Specialty: The AOWD certification allows diving to 100 feet 30 meters. Deep diver training adds another 30 feet/ 10 meters allowing the diver to dive to recreational limit of 130 feet/ 40 meters.
• Enrich Air Nitrox Diver (EAN) Specialty: Dives must be certified to dive with enriched air. There are additional steps that must be done when diving with EAN and additional risk to address.
• Overhead Environments Specialties: Diving in an overhead environment, one that does not have a direct ascent to the surface, requires a special certification. Wreck penetration is the most common overhead environment, however, it also included cavern and ice diving. These certifications train for the additional risk these environments address
• TEC: The Technical programs are beyond the scope of the recreational diver. They can include deeper depths than the recreational diver can accomplish, use of different breathing gasses and decompression diving. Additional training is required to become a technical diver.

Many divers will take the first three of these programs and not feel the need to take any other training. If you are interested in any of the other specialties, they are nice to have but not required for you to try it yourself. Provided you stay in the depth limits of your certification.

Specialty programs

The specialty programs are geared towards teaching a diver the skills they need to enjoy a certain type of dive. Other than the ones listed above as mandatory, you are not required to take a specialty to do a dive in those conditions. They are designed to help you learn what may interest you. Each of the dive accreditation agencies have about a dozen courses that you can explore. Many divers find the marine life orientated specialties very helpful in understanding the marine life around them. Night diving is another one that many divers will choose, because it allows them to understand more the night experience.
PADI also has a program called Distinctive Specialties. These programs are designed by dive instructors and are less widely available. Some of these are designed to be done at only one location.

What is an Advance Open Water Diver

Many experience divers do not like the name of PADI’s Advance Open Water Diver program. They feel that the word advance gives a false sense of competency to the new diver. Student divers are able to combined the Open Water Diver program and the Advance Open Water Diver program into one course and be verified as an AOWD with only 9 open water dives. PADI points out that they mean it as advance training, not that the diver has advance skills. Scuba Schools International takes a different view. Their Advance Adventure Diver Training, is the same as PADI’s AWOD. SSI does have an Advance Open Water Diver, however, it requires at least 24 dives and completion of the Advance Adventure Diver Training.
PADI’s AOWD diver program is based on completing the first dive of five different specialties. Two of the specialties are mandatory, these are deep diver and navigation. The other three are selected by the diver so the course best fits their needs. The training method used in the advance course is the same as in the open water class as they use the knowledge portion, the confined water session and pen water sessions.

Adventure dives

The term adventure dive is a fairly recent concept to the dive training. The first dive of a specialty program has always been an element of the Advance courses. However, they were not available separately. Now they are available to certified divers as an adventure dive. The diver experiences the same lesson as the first dive including knowledge and confined water if included, as a student taking a specialty. Divers who take three adventure dives can receive an adventure diver certification. This works similar to the way Scuba diver is about half of the Open Water Diver. While each specialty has its own knowledge manual, the adventure diver knowledge material is grouped together so only one knowledge package is needed.

Rescue Diver

The Rescue Diver certification for PADI and SSI’s Diver Stress & Rescue certification, are a different type of specialty course and the most demanding of all the recreational diving programs. While the other programs have been designed to help you improve your diving, this one expands to helping other divers. A first aid certification is a prerequisite to start this training. It takes your previously learned in-water skills and your first aid training and applies it in simulated emergency situations. It requires rescuing “victims” and starting the first responder treatments. You will learn different methods to handle a variety of situations. The program also includes skills such as accident management. This course is the prerequisite to enter the professional training programs to become a dive master/ dive leader and on to instructor.

Master Diver or Dive Master

In recreational scuba diving the terms Master diver and dive master mean two entirely different things. The dive master is the first professional rating in recreational scuba diver and is the path from rescue diver to instructor ratings. Master Diver is the highest rating outside the professional progression. Only 5% of scuba divers will ever earn the certification. The requirements for Master diver is the completion of rescue diver certification and holding certification in five additional specialties.
As an open water diver, it entirely up to you which path you will follow and even where on the path you wish to stop. Taking the Advance Open Water course is a very good option that most diver do and benefit from the extra training and additional depths. What do you find interesting under the sea?

The “Mystery” of Nitrox (EAN) Diving

It is a widely held believe that EAN-XX will allow you to dive deeper. Depending on how you look at it, that is only partially true. The belief revolves around the concept of equivalent air depth (EAD). Since, the air in the EAN-XX cylinder has a higher percentage of oxygen, that means it has a lower percentage of nitrogen. So less nitrogen is being absorbed into your tissues. If we have a standard fill at 21% oxygen (air) and dived to 80 feet /24 meters, we would have a NDL of 29 minutes (figures rounded).Using an EAN-32, we can dive to 100 feet/30 meters with the same bottom time of 29 minutes. At 32% oxygen, nitrogen is being absorbed at the same rate as 21% oxygen at 24 meters. So the EAD of EAN-32 at 100 feet/30 meters is 80 feet /24 meters. So for the same bottom time we can dive deeper.

While Nitrox diving has been used in recreational diving for over 25 years, there is still a degree of mystery about it. Even some misunderstanding what it can do for your diving. Because of this, many divers never undertake the short additional training that is required to qualify to dive Nitrox. Once you are training, diving with Nitrox only involves verifying the percentage before each dive. Nitrox is short for Nitrogen-oxygen, and is any blend of air where those two elements are the only ones other than trace elements. The air we breath is 21% oxygen and 79% nitrogen with small amount of trace elements. In recreational scuba diving, we can use what is called Enriched Air Nitrox (EAN). Blending an EAN mixture, we add 100% oxygen to normal air to increase the percentage of oxygen in the blend. We will generally see it as EAN-XX, where the XX is the percent oxygen in the blend. EAN-32 and EAN-36 are the most common and are used in the EAN dive tables. These two blends are commercially available, however, most dive centers that dive Nitrox can blend the mixture themselves so can have other percentages based on their needs. Divers qualified as Enriched Air Nitrox divers can dive using up to a 40% blend.

There is another factor that needs to consider, and that is Dalton’s Law of Partial Pressure. While some explanation of it is in your open water training and an expansion is in your advance open water and Nitrox / EAN training, we do not need a full understanding for our purpose here. When we are on land breathing, the partial pressure of oxygen, is .21ata. That value is made up of the percentage of oxygen times atmosphere pressure. When we dive to 33 feet/10 meters, we reach 2ATM and the partial pressure of oxygen (po2) becomes .42. Around this point the characteristics of how oxygen affect our bodies starts to change and oxygen becomes a toxin. However, the time it would take where the concentration would cause concerns are much longer than any diver would be still in the water. When the po2 increase to 1.6ata, the brain can start to become affected. This is called central nervous system (CNS) oxygen toxicity. At this point individuals will start showing signs of oxygen toxicity. These can rapidly escalate to convulsions and even death. For safety reasons, 1.4ata is considered the maximum safe partial pressure. When we are diving 21%, 1.4ata is reached at around 185 feet/56 meters. This is much deeper than we can dive due to the effects of nitrogen. However, if we switch to EAN-36 we will hit the 1.4ata safety limit at only 94 feet/ 28 meters. This is referred to as Maximum Operating Depth (MOD)and is well within range of a deep diver and before hitting the NDL based on nitrogen absorption. If we use EAN-38, the MOD is 87 feet/ 26 meters. So clearly, you cn not say EAN-XX can allow you to dive deeper. A final point, the oxygen off loading is the same as off loading nitrogen. The surface interval will reduce the amount in your system. Diving before the total is off loaded will not affect the ata point, however it will influence the time it takes to build up other toxic properties. While 100% oxygen is used in different medial situations, 100% oxygen will reach a po2 of 1.6ata in about 19 feet/6 meters of water.

Longer or safer?

The other benefits you will hear supporting EAN diving is that you can dive longer and safer. It is more accurate to say, EAN will allow you to dive longer or safer. Let’s use the same example as we used above, using air and diving to 80 feet /24 meters. We would have a NDL of 29 minutes for that dive. A diver using EAN-32 can stay at that depth giving him a NDL of 45 minutes almost 50% longer dive, before reaching the NDL. The air diver at 29 minutes and the EAN diver at 45 minutes have the same theoretical risk threshold. The EAN diver has had a longer dive but has not increased his safety. If both divers dive to the same depth and to the 29 minute mark, the air diver is at the NDL while the EAN diver has a large buffer, being still a time distance from his NDL. If they surface together, the EAN diver has a much safer profile.
Many dive professionals will use EAN to reduce their intake of nitrogen, even when diving with students on air. This gives them a greater safety margin.

When should I dive Nitrox / EAN and How to I become trained?

How long you can dive is really based on three factors, how fast you use your breathing gas (air or EAN), the NDL due to nitrogen and the oxygen loading. Few divers will benefit from the reduced nitrogen of an EAN blend if they are diving in less than 60 feet/ 18 meters. The deciding factor is the gas in the dive cylinder and not the other two factors.
Dives deeper than 60 feet/ 18 meters will benefit from an EAN mix, as long as it remains within the limits of the MOD. Diver preparing to dive EAN-XX must verify the oxygen content themselves, calculate the MOD, record the MOD on the tank and certified they did those steps. Those are the only task different for dive preparation. If using dive tables they will use EAN tables, it a dive computer they will enter the percentage.
Enriched Air Nitrox is a very simple certification class and can be combined with most other dive training. It consists of the knowledge portion and two open water dives. The two dives can be integrated into other training. Open water dive training will only integrate one dive, the second dive is additional. If you are not currently Nitrox / EAN qualified, you should explore a certification and join those with extended or safer diving.
Continue reading more from the DeeperBlue.com Beginners Guide to Scuba Diving.

Decompression Diving – What Is It and Should I Avoid It?

The term decompression diving is sometimes confusing for beginning divers. It brings forth the images of complicated formulas and in depth planning. They are told that it is “just” for technical divers who have vast amount of training and it not for mere recreational divers. They are right mostly, however, that does not mean that the recreational diver should not be aware of the topic and what it involves. In a broad definition, we can say that a decompression dive is one where the diver must make one or more mandatory stops prior to reaching the surface. The purpose of the stops are to allow the reduction of inert gases in the body. We refer to these mandatory stops as Deco stops.

In our Open Water Diver training we learned the importance of the dive tables. These tables gave us a set of guidelines we could use to safely dive to certain depths and how long we could stay there. This time limit is called the No-decompression limit (NDL). Staying within the NDL time and making a proper assent means there are no mandatory decompression stops. The second part of the table help us calculate the effects of nitrogen still in our body before our next dive. The surface internal and previous dive gave us a new NDL for our next dive at the depth we planned. In our training we learn that these table assumed a maximum assent rate. We generally see 30 feet per minute as the rate we wish to stay below. This slow controlled assent allows the body to continue to expel nitrogen from our tissue at a rate that balances its growth in size due to less pressure. It also helps prevents expanding air to be caught in the ears and chest causing ruptures. We are also taught that we should pause at 5 meters/15 feet for 3 minutes as a safety stop. This is the same as a deco stop as far as its effect on the body, allows more time to let the body expel gasses.

For the recreational diver, the question of should we avoid a decompression dive, the answer is a simple yes. The explanation might not be as you expect however. Let’s start by saying an Open Water Diver following the dive tables and staying within the limits of their certification will not likely encroach onto the decompression dive profile. On your first dive, you can stay at 60 feet/18 meters for about 55 minutes. Most divers will find that the amount of air remaining will require them to surface before reaching the NDL. Depending on the surface internal, the same may be true for the second dive. Advance Open Water and Deep Divers, however, can exceed NDL before reaching the air consumption limit. As an example let’s say a dive plan using computers calls for a descent to 30 meters/100 feet. The divers are to start to ascent when the first diver reaches 70 bar of gas remaining or 3 minutes NDL time. There will be a 3 minute safety stop at 5 meter/15 feet. Let’s assume a diver exceeds his NDL and breathes down to the 70 bar. His dive computer will go into “deco” mode and give him one or more “deco” stops. The more time past the NDL the more time and maybe more stops will be added. While a slow return to the surface with 70 bars would have left a safe air margin within NDL, the additional time required to ascend may exceed the remaining air. Very few divers, especially a new diver, can do an extended “Deco” dive on a single tank.

My Dive Computer says “Deco” What Do I Do?

First thing to do, is not to panic. If you just went into deco mode, the safety stop can still be short enough not to affect your ability to return to the surface. Ascend slightly and signal your dive buddy it is time to go up, let your buddy know you are in “deco”. Your dive computer will give you a depth where you need to make a safety stop. Ascend to that depth or slightly below it and level off. The computer will show you how long you need to remain at that depth, often with a countdown times. When you complete that stop, the dive computer will let you know if an additional stop is needed. If you were just slightly over the limit the next stop may be the 5 meter stop with a minute or two added. Longer time over the NDL may require an additional stop. If you miss a “deco” stop, your dive computer will go into a violation mode. It will still provide recommended stops, however, it will not start a new dive for 24 hours. Both you and your dive buddy must monitor your air consumption.

Practice a “Fake” Decompression Dive.

Reading and fully understanding your dive computer manual and applying it your computer is very important. Advance and deep divers have to pay close attention to the NDL on their computers. Knowing what to do and how your computer will react is critically important. Depending on your computer, you might be able to “fake” a decompression dive for training purposes. This is best done under supervision of an instructor. While there are many models of dive computers on the market, they all use a very small number of mathematical models. Even between different mathematical models the results are very similar. To accommodate divers with different risk factors, many computers will let you set your computer to be more conservative than the normal model, having a normal mode, conservative mode and a very conservative mode. There may be as much as 5 minutes difference between the different setting at 30 meters.

To experience a training decompression dive requires you to use two dive computers. Set your computer to the very conservative setting, and use the other as your control computer with the setting you normally would use. This exercise will not work if you normally dive in the very conservative setting. Dive at a depth within your certification level and let the very conservative set dive computer go into “deco”, however, do not exceed the NDL on the control computer. Follow the decompression dive instructions from your computer as you surface. This will give you the experience of using your computer if you accidentally go into a decompression situation.

Deep Diving Safety Stop

The addition of the safety stop at 5 meters/15 feet for recreational divers was design to provide a larger margin of safety. It is in fact the same thing that a deco stop does. Many deep dive recreational divers are adding a deep safety stop. This stop is at half the depth of the dive. So if you dived to 30 meters, the diver will do a deep stop at 15 meters. The stop is only for a minute or two, however, it will add a safety margin in addition to the 5 meter stop.

Training for Decompression Diving

As you become a more confident and efficient diver, you may reach a point here you would want to learn decompression diving. The training agencies offer introduction to technical diving programs that include decompression diving. PADI’s Tec 40 course and SSI’s Extended Range Nitrox are two examples. These programs do require other certifications and are for experienced divers, however, they are a worthy goal to stride for.

Continue reading more from the DeeperBlue.com Beginners Guide to Scuba Diving