* Scuba Diving Theory and Practice
SCUBA DIVING is an equipment intensive sport / recreation which requires proper training and the right attitude to enable a person to dive SAFELY and ENJOYABLY. Learning to dive is not difficult as many people think. Those who are in good health, eager to learn, and comfortable in the water, can join a Scuba course. When you pass or complete all the training requirements of the AGENCY (PADI, SSI, PDIC, NAUI, BSAC, etc.) of your choice, you are awarded an international certification card (C-card). It allows you to buy or rent diving equipment, have your scuba cylinders filled by reputable/accredited dive shops or air fill stations, and depending on climatic, ocean conditions, and level of training, dive anywhere in the world.
The following pieces of equipment are essential to a Scuba Diver:
1. Mask, snorkel, and fins
2. Regulator and alternate air source and power inflator device
3. Buoyancy Compensator Jacket (BCJ)
4. Air Cylinder
5. Time, pressure, and depth gauges / devices
6. Weight belt with lead weights
7. Wet suit, gloves, and booties
8. Dive knife, whistle, visual signaling devices
9. Decompression Table or Dive Computer
These have to be assembled, worn, and adjusted properly and accordingly. You and your buddy must conduct a thorough pre-dive equipment check or inspection. Look for leaks and ascertain that you have more than enough supply of air in your cylinder. Many diving accidents happen because of negligence or failure to do these simple exercises, and to check equipment condition, comfort, and fit before each dive. There are many ways to enter the water. The most common are the feet-first entry and the back roll or flip. As you do more dives, you should be able to select the most appropriate and comfortable method. When you start your dive, make sure that you remember your time of descent. Keep monitoring you gauges during the dive. Take note of your time of ascent and fully inflate your BCJ once you get back to the surface. It is also better to not to leave your mask sitting on your forehead as you may lose it easily when it accidentally slips off. Simply pull it down your neck and keep it there until you get out of the water. Before boarding the boat, take off your weight belt and hand it over to the boat assistant first. Remember to hold the open end of the weight belt, not the buckle, to prevent the lead weights from slipping out and getting lost. What piece of equipment that you may have to take off next shall depend on the boat size and design, on whether or not it has a ladder, and on sea conditions.
WHEN YOU START your descent, your mask will fog up because of the temperature differences between the air in your mask and the water around it unless you apply defogging solution, toothpaste, shampoo, or saliva on the inside lens before entering the water. Rub your choice from these substances evenly and vigorously. While you’re diving, WATER PRESSURE can cause problems, especially to untrained and careless individuals because it increases considerably as you go deeper. This compresses the lungs (higher PRESSURE = lower VOLUME, V.V.) to a point where you have to inhale more air to maintain your normal lung volume and oxygen level in your system proportionate to the pressure at any depth. As a consequence, it exposes your lungs and other body air spaces to the risk of getting ruptured, especially when you HOLD your BREATH as you ascend. The decrease in pressure while you ascend causes your lungs to expand. Since the lungs have limited capacity, it can no longer handle the increase in air volume and will burst. This malady is called AIR EMBOLISM and is extremely dangerous. For your safety, NEVER HOLD YOUR BREATH while SCUBA diving.
During a dive, an OUT-OF-AIR situation may happen because of one’s failure to follow standard DIVING procedures, or equipment malfunction due to poor or lack of maintenance. It could happen to you or anybody if you are using rental equipment from fly-by-night dive operators or when you do not follow proper equipment maintenance and repair procedures. In this type of situation, the safest way out is to share air with your buddy using the octopus or alternate air source. You may also do a controlled or emergency swimming ascent, depending on your immediate need, but make sure that you exhale continuously thru your regulator mouthpiece as you ascend to prevent lung expansion injury. Your regulator mouthpiece may also slip off your mouth while you are underwater and when it does, NEVER HOLD YOUR BREATH! You must EXHALE a stream of air to lessen your lung volume while you are attempting to retrieve or recover your regulator mouthpiece. Once it is back in your mouth, and before you resume breathing, immediately purge the water by blowing it out thru the mouthpiece or by pushing the mouthpiece purge button. Breathe in a slow and deep manner to help maintain normal oxygen level in you brain. Since you are breathing filtered and dry compressed air, it becomes more difficult for you to swallow. It causes a bit of discomfort which can be remedied by sipping and swallowing a bit of seawater. You may also cough or sneeze thru your mouthpiece but make sure it stays in place.
WATER PRESSURE also affects your other AIR SPACES, especially your middle ear, sinuses, and also your dive mask. You must equalize these air spaces every 2-3 feet by attempting to blow thru your nose while you while you pinch your nostrils shut and to exhale thru your nose into the mask to equalize as you descend to avoid discomfort or problems caused by the squeezing effect of increasing pressure. Your descent rate depends on how well and how fast you are able to equalize. When you return to the surface, the pressure around you decreases, which causes air that is trapped in your middle ear and sinuses to expand. You should always do your best to avoid this problem as it leads to a malady called REVERSE BLOCK. If it’s not remedied at an earlier stage, it can rupture your eardrums and also damage your sinuses. Improper equalization leads to another malady called VERTIGO (dizziness). To prevent these pressure-related problems, never dive when you have a COLD, as mucus blocks your nasal / sinus passages and prevents normal respiratory process and equalization of your air spaces. Likewise, do not dive when you are really not “up to it” or when sea conditions are not conducive to diving.
COMPRESSED AIR is about 21% OXYGEN and 79% NITROGEN. Under pressure, each gas has separate and varying effect on a diver, depending on his / her physical and physiological condition. When you dive TOO DEEP and TOO LONG, NITROGEN causes DECOMPRESSION sickness or the BENDS. It also has a NARCOTIC effect on divers at depths of over 30meters. To avoid the BENDS, dive within the limits as shown on the DIVE TABLE or COMPUTER while the remedy for NITROGEN NARCOSSIS is to ascend to a shallower depth. As far as OXYGEN is concerned, its partial pressure reaches a critical stage at over 60 meters compared to its PURE state which becomes toxic and hazardous in only 10 meters of seawater. Ignorance regarding the effects of pressure on these gases and disregarding the safety measures or standards relative to them may lead to physical or physiological health problems or even DEATH. Because of this, it is recommended that you use only the services of REPUTABLE or ACCREDITED dive operators for your PURE AIR requirements.
WATER conducts HEAT about 20 times faster than AIR and results to a malady called HYPOTHERMIA. When diving in water with temperatures of about 28 degrees Centigrade or lower, you need to wear a WET SUIT. Its thickness depends on water temperature variation. You will require thicker wet suits as the water gets colder. In tropical waters during summer, the temperature is warm enough for you not wear one, but you still need to wear some protective garments against stinging marine life, like jellyfishes, fire corals, hydroids, etc. UNDERWATER VISION improves by about 30% so things look bigger or nearer. This is caused by refraction or bending of light rays when they hit the water surface. As you go deeper, there’s less light that reaches the bottom and this causes reduction in color intensity. Bright colors, depending on their respective hues, disappear at depths where there’s very minimal natural lighting. At these depths, everything looks dull and sort of grayish. RED turns into GREEN! To bring back the colors and improve underwater visibility, the best thing to do is to use an underwater torch or flashlight.
SOUND travels 4 times faster, hence, you can hear a lot better underwater. Because of this, it is difficult to trace where a particular sound originates. Using a dive knife to bang your tank is one way to get your buddy’s attention. There are also many other types of audible signaling devices for this purpose. Using HAND SIGNALS and underwater slates for writing are also essential and effective means to communicate while you are diving.
PROPER BUOYANCY CONTROL is a very important skill. It helps minimize physical exertion, which, in turn, improves your air consumption rate. It also allows you to hover, and avoid holding, touching, hitting, or breaking corals. Good buoyancy control makes it possible to regulate your rate of descent and helps to prevent the occurrence of pressure related maladies such as ear, sinus, or mask squeezes. Without the right buoyancy, you could sink faster than you need to or experience other problems even while you are still on the surface, especially when you are using more lead weights than you require. To find your neutral buoyancy, you need to get in the water while you are wearing your full set of SCUBA gear. With your BCJ fully deflated, allow yourself to float first without any lead weight on your belt. Then inhale deeply, stop all movement, and allow yourself to sink at EYE LEVEL by putting on some lead weights, a kilo or two at a time, until you start sinking and your eyes are on the same level as the water surface. Once you find your neutral buoyancy, diving shall be a lot more enjoyable and relaxing. As you descend, always make it a point to look down and around you often. On your way back to the surface always look up and around you and listen for any approaching watercrafts. Don’t forget to extend an arm upwards as you near the surface. These precautionary measures help to prevent you from getting hurt. Once you are back on the surface, fully inflate your BCD using the power inflator, or orally if you are out of air.
The EARTH’S rotation and GRAVITATIONAL pull of the moon causes TIDAL changes and diving during a TIDAL change can be quite exciting but you need to exercise extreme caution to avoid accidents. As a rule, you have to dive against the CURRENT to make it easier for you to return to the boat at the end of the dive or when you decide to it short. Use the anchor rope when you descend. Swimming against A STRONG current will make you very tired so when this happens, use your knife to anchor yourself in the sand, or hang on to a rock or solid object, and take a couple of quick deep breaths until you feel better and ready to move. Avoid strong currents unless you have the experience and training. If the REEF is big enough, or if conditions allow it, it’s better and easier to just follow the direction of its flow. Use current lines by leaving a rope with a buoy attached to the other end by letting it float with the current at least 50 meters away. In case you miss the boat, you can swim diagonally towards it and use it to get you back to the boat. Make sure that the current line is always connected securely to the boat.
Even before you leave for a dive trip, you can predict what sort of sea conditions to expect by monitoring wind intensity and direction. Wind causes waves to form and the direction of the wind forces the waves to move energetically or forcefully to where it is blowing. This process creates surface current and rough water conditions that could spell trouble to an experienced diver before or after a dive. It could also lead to problems for small sea crafts. So before you leave for a dive point, make sure that the weather and sea conditions are manageable and relative to your training level, experience, and the type of sea craft that you are using. Always make sure that you have first aid, oxygen kit, and an evacuation plan for every trip. Having a marine radio on board to contact the Coast Guard or a diving emergency group may save lives. You may also relay your request for an emergency evacuation by telephone directly to DIVERS ALERT NETWORK (DAN) or any MEDICAL EMERGENCY / RESCUE UNIT your area.
During diving activities, leave a floating marker or DIVE FLAG on the surface to keep boat traffic away to avoid accidents. Before you enter the water, review safety and emergency procedures with your buddy and do thorough equipment/buddy check. Make sure that your air supply is adequate in relation to your air consumption rate and dive plan. Note your time of descent and ascent. While underwater, always monitor your time, air pressure, and depth gauges.
After the Dive, carefully dismantle your equipment and get them ready for fresh water rinsing when you get back to the dive shop. Leave them to dry under a shaded area before you store them. Never leave pieces of your equipment, especially a full air cylinder, directly exposed to the heat or sun rays. Every now and then, bring them to a specialist for maintenance or repair as required. Air cylinders need to be VISUALLY inspected EVERY YEAR and HYDRO-TESTED for maximum pressure tolerance every five (5) years. Well-kept and maintained equipment can give you years of enjoyment and safety.
Keep a record of all your dives and don’t forget to bring them with you on trips. Without your training and fun-diving records, you may not be allowed to purchase equipment or join diving activities by legitimate dive operators. You may also want to upgrade your skills on a periodic basis. In this regard, training documents / proofs of diving proficiency are required.
Lastly, as a SCUBA DIVER, you have to commit yourself to helping keep our marine environment clean and as natural as possible. We must all guard against illegal and indiscriminate methods for harvesting or collecting marine life. We must show others that for as long as we care, Mother EARTH shall continue to be a great place to live in, appreciate, and enjoy.
Here’s to a SAFE and ENJOYABLE diving!
NOTE: You need special instructions in the use of DIVE COMPUTERS, and to have professional supervision while you undergo training in water skills and emergency situations, equipment orientation and use. As far as finding your dive time and depth limits, a lecture on the proper use of the dive tables is part your training requirements.
For more details, you may call or text +639164528197 or email divetrainor@gmail.com
The following pieces of equipment are essential to a Scuba Diver:
1. Mask, snorkel, and fins
2. Regulator and alternate air source and power inflator device
3. Buoyancy Compensator Jacket (BCJ)
4. Air Cylinder
5. Time, pressure, and depth gauges / devices
6. Weight belt with lead weights
7. Wet suit, gloves, and booties
8. Dive knife, whistle, visual signaling devices
9. Decompression Table or Dive Computer
These have to be assembled, worn, and adjusted properly and accordingly. You and your buddy must conduct a thorough pre-dive equipment check or inspection. Look for leaks and ascertain that you have more than enough supply of air in your cylinder. Many diving accidents happen because of negligence or failure to do these simple exercises, and to check equipment condition, comfort, and fit before each dive. There are many ways to enter the water. The most common are the feet-first entry and the back roll or flip. As you do more dives, you should be able to select the most appropriate and comfortable method. When you start your dive, make sure that you remember your time of descent. Keep monitoring you gauges during the dive. Take note of your time of ascent and fully inflate your BCJ once you get back to the surface. It is also better to not to leave your mask sitting on your forehead as you may lose it easily when it accidentally slips off. Simply pull it down your neck and keep it there until you get out of the water. Before boarding the boat, take off your weight belt and hand it over to the boat assistant first. Remember to hold the open end of the weight belt, not the buckle, to prevent the lead weights from slipping out and getting lost. What piece of equipment that you may have to take off next shall depend on the boat size and design, on whether or not it has a ladder, and on sea conditions.
WHEN YOU START your descent, your mask will fog up because of the temperature differences between the air in your mask and the water around it unless you apply defogging solution, toothpaste, shampoo, or saliva on the inside lens before entering the water. Rub your choice from these substances evenly and vigorously. While you’re diving, WATER PRESSURE can cause problems, especially to untrained and careless individuals because it increases considerably as you go deeper. This compresses the lungs (higher PRESSURE = lower VOLUME, V.V.) to a point where you have to inhale more air to maintain your normal lung volume and oxygen level in your system proportionate to the pressure at any depth. As a consequence, it exposes your lungs and other body air spaces to the risk of getting ruptured, especially when you HOLD your BREATH as you ascend. The decrease in pressure while you ascend causes your lungs to expand. Since the lungs have limited capacity, it can no longer handle the increase in air volume and will burst. This malady is called AIR EMBOLISM and is extremely dangerous. For your safety, NEVER HOLD YOUR BREATH while SCUBA diving.
During a dive, an OUT-OF-AIR situation may happen because of one’s failure to follow standard DIVING procedures, or equipment malfunction due to poor or lack of maintenance. It could happen to you or anybody if you are using rental equipment from fly-by-night dive operators or when you do not follow proper equipment maintenance and repair procedures. In this type of situation, the safest way out is to share air with your buddy using the octopus or alternate air source. You may also do a controlled or emergency swimming ascent, depending on your immediate need, but make sure that you exhale continuously thru your regulator mouthpiece as you ascend to prevent lung expansion injury. Your regulator mouthpiece may also slip off your mouth while you are underwater and when it does, NEVER HOLD YOUR BREATH! You must EXHALE a stream of air to lessen your lung volume while you are attempting to retrieve or recover your regulator mouthpiece. Once it is back in your mouth, and before you resume breathing, immediately purge the water by blowing it out thru the mouthpiece or by pushing the mouthpiece purge button. Breathe in a slow and deep manner to help maintain normal oxygen level in you brain. Since you are breathing filtered and dry compressed air, it becomes more difficult for you to swallow. It causes a bit of discomfort which can be remedied by sipping and swallowing a bit of seawater. You may also cough or sneeze thru your mouthpiece but make sure it stays in place.
WATER PRESSURE also affects your other AIR SPACES, especially your middle ear, sinuses, and also your dive mask. You must equalize these air spaces every 2-3 feet by attempting to blow thru your nose while you while you pinch your nostrils shut and to exhale thru your nose into the mask to equalize as you descend to avoid discomfort or problems caused by the squeezing effect of increasing pressure. Your descent rate depends on how well and how fast you are able to equalize. When you return to the surface, the pressure around you decreases, which causes air that is trapped in your middle ear and sinuses to expand. You should always do your best to avoid this problem as it leads to a malady called REVERSE BLOCK. If it’s not remedied at an earlier stage, it can rupture your eardrums and also damage your sinuses. Improper equalization leads to another malady called VERTIGO (dizziness). To prevent these pressure-related problems, never dive when you have a COLD, as mucus blocks your nasal / sinus passages and prevents normal respiratory process and equalization of your air spaces. Likewise, do not dive when you are really not “up to it” or when sea conditions are not conducive to diving.
COMPRESSED AIR is about 21% OXYGEN and 79% NITROGEN. Under pressure, each gas has separate and varying effect on a diver, depending on his / her physical and physiological condition. When you dive TOO DEEP and TOO LONG, NITROGEN causes DECOMPRESSION sickness or the BENDS. It also has a NARCOTIC effect on divers at depths of over 30meters. To avoid the BENDS, dive within the limits as shown on the DIVE TABLE or COMPUTER while the remedy for NITROGEN NARCOSSIS is to ascend to a shallower depth. As far as OXYGEN is concerned, its partial pressure reaches a critical stage at over 60 meters compared to its PURE state which becomes toxic and hazardous in only 10 meters of seawater. Ignorance regarding the effects of pressure on these gases and disregarding the safety measures or standards relative to them may lead to physical or physiological health problems or even DEATH. Because of this, it is recommended that you use only the services of REPUTABLE or ACCREDITED dive operators for your PURE AIR requirements.
WATER conducts HEAT about 20 times faster than AIR and results to a malady called HYPOTHERMIA. When diving in water with temperatures of about 28 degrees Centigrade or lower, you need to wear a WET SUIT. Its thickness depends on water temperature variation. You will require thicker wet suits as the water gets colder. In tropical waters during summer, the temperature is warm enough for you not wear one, but you still need to wear some protective garments against stinging marine life, like jellyfishes, fire corals, hydroids, etc. UNDERWATER VISION improves by about 30% so things look bigger or nearer. This is caused by refraction or bending of light rays when they hit the water surface. As you go deeper, there’s less light that reaches the bottom and this causes reduction in color intensity. Bright colors, depending on their respective hues, disappear at depths where there’s very minimal natural lighting. At these depths, everything looks dull and sort of grayish. RED turns into GREEN! To bring back the colors and improve underwater visibility, the best thing to do is to use an underwater torch or flashlight.
SOUND travels 4 times faster, hence, you can hear a lot better underwater. Because of this, it is difficult to trace where a particular sound originates. Using a dive knife to bang your tank is one way to get your buddy’s attention. There are also many other types of audible signaling devices for this purpose. Using HAND SIGNALS and underwater slates for writing are also essential and effective means to communicate while you are diving.
PROPER BUOYANCY CONTROL is a very important skill. It helps minimize physical exertion, which, in turn, improves your air consumption rate. It also allows you to hover, and avoid holding, touching, hitting, or breaking corals. Good buoyancy control makes it possible to regulate your rate of descent and helps to prevent the occurrence of pressure related maladies such as ear, sinus, or mask squeezes. Without the right buoyancy, you could sink faster than you need to or experience other problems even while you are still on the surface, especially when you are using more lead weights than you require. To find your neutral buoyancy, you need to get in the water while you are wearing your full set of SCUBA gear. With your BCJ fully deflated, allow yourself to float first without any lead weight on your belt. Then inhale deeply, stop all movement, and allow yourself to sink at EYE LEVEL by putting on some lead weights, a kilo or two at a time, until you start sinking and your eyes are on the same level as the water surface. Once you find your neutral buoyancy, diving shall be a lot more enjoyable and relaxing. As you descend, always make it a point to look down and around you often. On your way back to the surface always look up and around you and listen for any approaching watercrafts. Don’t forget to extend an arm upwards as you near the surface. These precautionary measures help to prevent you from getting hurt. Once you are back on the surface, fully inflate your BCD using the power inflator, or orally if you are out of air.
The EARTH’S rotation and GRAVITATIONAL pull of the moon causes TIDAL changes and diving during a TIDAL change can be quite exciting but you need to exercise extreme caution to avoid accidents. As a rule, you have to dive against the CURRENT to make it easier for you to return to the boat at the end of the dive or when you decide to it short. Use the anchor rope when you descend. Swimming against A STRONG current will make you very tired so when this happens, use your knife to anchor yourself in the sand, or hang on to a rock or solid object, and take a couple of quick deep breaths until you feel better and ready to move. Avoid strong currents unless you have the experience and training. If the REEF is big enough, or if conditions allow it, it’s better and easier to just follow the direction of its flow. Use current lines by leaving a rope with a buoy attached to the other end by letting it float with the current at least 50 meters away. In case you miss the boat, you can swim diagonally towards it and use it to get you back to the boat. Make sure that the current line is always connected securely to the boat.
Even before you leave for a dive trip, you can predict what sort of sea conditions to expect by monitoring wind intensity and direction. Wind causes waves to form and the direction of the wind forces the waves to move energetically or forcefully to where it is blowing. This process creates surface current and rough water conditions that could spell trouble to an experienced diver before or after a dive. It could also lead to problems for small sea crafts. So before you leave for a dive point, make sure that the weather and sea conditions are manageable and relative to your training level, experience, and the type of sea craft that you are using. Always make sure that you have first aid, oxygen kit, and an evacuation plan for every trip. Having a marine radio on board to contact the Coast Guard or a diving emergency group may save lives. You may also relay your request for an emergency evacuation by telephone directly to DIVERS ALERT NETWORK (DAN) or any MEDICAL EMERGENCY / RESCUE UNIT your area.
During diving activities, leave a floating marker or DIVE FLAG on the surface to keep boat traffic away to avoid accidents. Before you enter the water, review safety and emergency procedures with your buddy and do thorough equipment/buddy check. Make sure that your air supply is adequate in relation to your air consumption rate and dive plan. Note your time of descent and ascent. While underwater, always monitor your time, air pressure, and depth gauges.
After the Dive, carefully dismantle your equipment and get them ready for fresh water rinsing when you get back to the dive shop. Leave them to dry under a shaded area before you store them. Never leave pieces of your equipment, especially a full air cylinder, directly exposed to the heat or sun rays. Every now and then, bring them to a specialist for maintenance or repair as required. Air cylinders need to be VISUALLY inspected EVERY YEAR and HYDRO-TESTED for maximum pressure tolerance every five (5) years. Well-kept and maintained equipment can give you years of enjoyment and safety.
Keep a record of all your dives and don’t forget to bring them with you on trips. Without your training and fun-diving records, you may not be allowed to purchase equipment or join diving activities by legitimate dive operators. You may also want to upgrade your skills on a periodic basis. In this regard, training documents / proofs of diving proficiency are required.
Lastly, as a SCUBA DIVER, you have to commit yourself to helping keep our marine environment clean and as natural as possible. We must all guard against illegal and indiscriminate methods for harvesting or collecting marine life. We must show others that for as long as we care, Mother EARTH shall continue to be a great place to live in, appreciate, and enjoy.
Here’s to a SAFE and ENJOYABLE diving!
NOTE: You need special instructions in the use of DIVE COMPUTERS, and to have professional supervision while you undergo training in water skills and emergency situations, equipment orientation and use. As far as finding your dive time and depth limits, a lecture on the proper use of the dive tables is part your training requirements.
For more details, you may call or text +639164528197 or email divetrainor@gmail.com
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