Beginner Tips: Buoyancy Control
By Shelley Collett
Have you ever seen those divers out there just effortlessly floating inches above the bottom, moving as if they were one with the water, expending little, if any energy to swim around? Ever wish you could do that too? Well you can. All it takes is some knowledge and practice. And in my not so humble opinion, aside from an understanding of Boyle’s Law and how it relates to scuba diving, buoyancy control is the number one thing to have down pat. I can help a wee bit with the knowledge, but the practice is all on you!
First off, why should you have good buoyancy control? Well that’s a great question! It helps to understand why you should do something in the first place. What advantages will good buoyancy control give you...
- Less air consumption (you expend less energy, so you use less air)
- Less effort - so you’re not as tired (and you use less air)
- Lower chance of harming marine life (sorry about that crater hole in the reef!)
- Lower chance of harming yourself ON marine life (like banging your face on fire coral)
- Lower chance of harming yourself on ascent (oops, blew right through that safety stop!)
- You don’t have to lug around as much weight (or pay as much in luggage fees)
- You feel more at ease and comfortable in the water (as opposed to feeling like a large bull with an air supply)
- You feel more in control
- Because of the last two, you gain confidence
- You look cool (this is, of course, the most important one)
Power inflator is NOT an elevator button
If you inflate to ascend, you run a big risk of an out of control ascent. Remember Boyle’s Law? The air you put in at depth is going to expand as you go up, and the more you go up, the more buoyant you’re going to become. At a certain point, you’re not going to be able to control your ascent any longer and you will have put yourself at risk of DCS as you rocket to the surface like a cork. I’ve been there and done that, it’s not fun!
This may seem contrary to common sense, but you should only inflate to stop a decent and then you deflate while you’re ascending. In other words, while underwater, you’re actually going to inflate on your way down and deflate on your way up. In fact, try to use your power inflator as little as possible in general, and when you do use it, make very small adjustments.
Okay, now that’s out of the way.
The Right Gear
First off, make sure your BCD fits properly. A BCD that’s too big or too small is going to make your buoyancy control that much more difficult. It should hug your body, not pinch it and not move around much independently. You want to make sure you have the right amount of lift for the diving conditions you’re going to be in, too. In colder water, you’ll need more weight and your BCD needs to be able to handle that.
Weights and Trim
Once you’re clear on how to use your power inflator, or rather now NOT to use it, weights and trim are your next step in becoming a buoyancy control expert. Lugging around too much weight underwater can increase your drag, force you to use much more air in your BCD to compensate, and will wear you out in the process. Try this test. Go to a pool or some other easily accessible body of water. Do the buoyancy check (no air in BCD, holding breath, float at eye level) starting with zero extra weight. Then keep adding a couple pounds and redoing the check until you float at eye level with an empty BCD and a normal breath held. Now, descend (remember to exhale fully!), and swim around. Come back to the surface and grab 5 - 10 lbs of weight (the average amount of extra weight divers carry that they don’t need to) and descend again and swim around. You will see how much more effort it takes to swim around with that extra weight. Just try it. It may surprise you. Remember that your descent should be slow, and also remember to put on a couple extra pounds in anticipation of a lighter tank at the end of the dive.
As much as you don’t want to be too heavy, you don’t want to be too light either. If you have to struggle to get down and you’re sure you’ve fully exhaled and fully emptied your BCD, then you’re underweighted. Don’t force yourself down because when you come back up on ascent with a lighter tank, you could end up with an out of control ascent. Another tip about difficult descents: Sometimes it’s just that the BCD isn’t completely empty. Be sure to raise the inflator hose high, lean to the right a little, and lean back just a tad. That should get it completely empty.
Everyone is different when it comes to trim. Do what makes you feel the most comfortable, but figuring that out may take some trial and error. Some folks are perfectly fine with all of their weight in their BCD front weight pockets. Personally, I like my weight distributed all over my body. I wear ankle weights, tank weights, and put weight in my BCD front and back pockets. That’s just me, though. Experiment with trim weights and see if it makes you feel more streamlined.
Look Ma, No Hands
While diving, your hands should be used to check gauges, computers, adjust your BCD, point at pretty things, and poke your buddy. What they should not be used for is swimming. Yes, sometimes you find yourself listing to one side or another. That’s where the trim weighting (see above) comes into play. Some of us have more muscle mass on one side or another and will just naturally tilt that way. Fix those problems with trim weights, not your hands.
Swimming with your hands in general is a big no-no in scuba diving. For one thing, it’s dangerous to all of the divers around you. Your flailing limbs are just unexpected obstacles they have to try to avoid so they don’t get smacked in the head, or their mask knocked off, or their regulator knocked out of their mouth. Secondly, you’re scaring all the fish away! Third, you’re risking beating your limbs on someone or something and injuring yourself. Fourth (this list just keeps getting longer the more I think about it) you’re wasting energy and if you’re wasting energy, then you’re wasting air. That’s a scuba diving party foul. Fifth, it doesn’t help anything. Your legs are your power, your arms do very little underwater (see the whole wasted energy thing). And last, you’re making it harder to feel the buoyancy adjustments you need to make. By flailing around and using your hands to try to adjust your buoyancy, you’re not learning how to do it with your lungs or BCD. You need to feel those sensations, understand them, and then compensate using your lungs, inflator, or your fins.
There are times that a rapid swimming adjustment must be made and hands must be used, but those are few and far between. If you can’t seem to stop using them, then force yourself to clasp your hands together, or grab onto your BCD somewhere comfortable. Get your hands doing something else to help keep you from immediately flailing them out.
Horizontal. That’s how you should be diving. Not only diving, but it’s how you should descend too. As you descend, you start to pick up speed as your wetsuit compresses and the atmospheres add up above you. If you make yourself horizontal as you’re descending you can more easily see the bottom you are plummeting towards, and as your body creates more drag it will naturally slow your descent. Small bursts of air will help control your body too, and help to prevent you from cratering into the sediment or reef below. If you’re not sure what cratering is, go to the bottom of a lake, quarry, etc, where a lot of new divers are being trained and just watch. You’ll see them drop like rocks to the bottom then hit the bottom with a great big POOF! as a crater is formed in the sediment around where they landed. That’s cratering. Stop doing that.
Horizontal is best while swimming around too. Not slightly angled up... not slightly angled down. Either of those positions means you’re not weighted properly. You should be horizontal for ease of movement, range of vision, and best buoyancy control. If you’re angled slightly up, each fin kick is going to move you up, vice versa for being angled down. Just like driving, people tend to go the direction they are looking. Be aware of this and try to maintain a horizontal position, and if you do look up to take in some scenery, stop kicking.
Remember a couple paragraphs up I said that you should use your power inflator as little as possible? You may have wondered how, or why. The answer to both is: use your lungs. Once you’ve used your inflator to get neutrally buoyant on your initial descent, you really should rely primarily on your lungs from there on out. Big deep breaths will cause you to rise a little in the water column, big deep exhales will make you drop a bit. Use these to your advantage while diving and you’ll find that you’ll need to kick less and spend less time fighting your buoyancy because you accidentally added too much air to your BCD. The only way to truly master this is to practice, practice, practice. You know that brief hovering skill you did for your open water cert? You should be practicing that all the time until it becomes natural for you. It’s real easy to just grab that inflator and pop some air in, but fight that urge. Try using your lungs instead. Imagine this scenario:
You’re diving along a beautiful reef when you come to an area you need to go up and over. You take a deeper than normal breath and let your natural buoyancy lift you gently upward as you continue with your normal kicking. Once you’re up a little bit, you resume breathing normally. Then, as you need to come down the other side, you exhale deeper than usual, allowing yourself to easily sink deeper in the water before resuming your normal breathing cadence.
Doesn’t that sound much better than kicking your way up and kicking your way back down? Or putting air in your BCD, only to realize that once you do go up a little bit that you’re too buoyant and must now let air back out as you fight to get back down to your desired depth?
One of the biggest problems with newer divers is that they’re very tense, with good reason. You know how you did a weight check in a pool somewhere and you know what weight you should be using, but you just can’t seem to go down right now? Chances are you’re all tensed up and are holding extra air in your lungs. You don’t even realize you’re doing it, it’s just a matter of not being relaxed and the air just isn’t coming out. I know it’s easier said than done sometimes, but relax. Take some nice deep cleansing breaths, and let them fully out. I tell people to fully exhale and they blow out a little puff. Most of us don’t realize just how much air our lungs can and do hold. Practice relaxing your muscles to allow yourself to really fully exhale. Do it on land when you are very relaxed so you can feel what it's like to fully exhale, then remember that when you’re trying to descend.
Aside from descending issue, being tensed up in general will affect your buoyancy control. Have you ever tried to float on your back on the surface of the water while tensed up? You can’t do it. You have to relax to float. Well, at least I do! Similarly, you need to relax to have good buoyancy control underwater too. This takes some time, comfort, and confidence to get there though. Speaking of which...
Practice Makes Perfect
You have to practice these things. The best divers among us weren’t born knowing how to float effortlessly while sitting in a buddha fin-holding position. It takes practice to get there. We can tell you what you need to do, we can give you pointers, we can show you, and we can tell you what works and what won’t, but to master this you need to FEEL it. And that, my friends, is a very personal thing that you have to attain on your own. Eventually, it will click. That lightbulb will go on and you’ll wonder why it seemed so hard to begin with. I promise you. Practice WILL make perfect. Every chance you get, just do it. You’ll thank me later when you’re carrying less weight, using less air, feeling less tired, and aren’t being maimed from crashing into reefs.
9 Pieces of Gear Every Diver Should Know
By Thomas Gronfeldt
Properly using these 10 items will make your dives safer and more enjoyable
1. DSMB A delayed surface marker buoy (DSMB), or safety sausage, is a long, tube-shaped balloon, usually orange, that you inflate underwater with your regulator or octopus, sending it to the surface to signal the dive boat or someone on shore of your presence. It is often used in situations of moderate to high current to let the Zodiac know where you are after a dive ends. But simple as it sounds, it can be tricky to use these properly, and divers tend to get tangled up in the line or to ascend uncontrolled along with the DSMB, so practice is important.
A jonline is a simple hook or carabiner attached to about 6 feet of webbing. If you’re stuck on a shot line during a safety stop with lots of other divers, it can be difficult for everyone to stay within the safety-stop zone. By attaching the jonline to the shot line, you can move away from the shot line without being carried off by a current, leaving more room for everyone else.
I’m not the world’s biggest fan of snorkels, but if you do bring one, make sure you know how to use it. Take the time to learn how to breathe effectively in it, how to clear it, and how to place it properly so it doesn’t get in your way. I’ve seen a number of people nearly drown from inefficient snorkel clearing.
4. Trauma shears
Knives are popular, but often trauma shears can be even more effective. They can be operated with one hand, even while cutting a line; there’s less risk of inflicting damage on yourself or others; and there is less potential for legal issues when traveling.
5. Line reel
Line reels are one of the multi-tools of scuba diving. Often used for an easy return to a specific point, such as an ascent point or an exit point in a wreck or cave, or to tether onto a surface buoy, they are inexpensive and reliable. They do tend to get into a tangled mess if you’re not vigilant, so learning proper line-handling skills is important.
6. Signaling mirror
A diver on the surface doesn’t have a very large profile, making him hard to spot even for people who are actively looking. And the ambient sounds at sea make it nearly impossible to shout loud enough to get someone’s attention. So if you need to communicate with someone, either on land or on a boat, a simple signaling mirror can do the trick, even over fairly long distances. At night, a powerful dive torch can do the same.
7. Dive computer
Most people have computers, but few take the time to get to know their functions. Nothing is more disconcerting than seeing a warning go off during a dive and having no idea what it means. Read the instruction manual thoroughly and get to know your new dive computer’s functions.
8. Reef hook
A controversial piece of equipment, the reef hook is used to hold on to a reef if you need to come to a stop in a strong current, either to wait for a potential marine life sighting, to prevent yourself from being swept away, or as part of a safety stop. If used incorrectly, they can damage sensitive coral reefs, but when used correctly they can be a lot less damaging than holding on to the reef with your hand. Place them only on the rocky part of a reef, and check for plant or animal life first.
9. Common sense
While not, strictly speaking, a piece of gear, common sense is still the single most important thing to use before, during and after a dive. Remember your training, respect your limitations and don’t do anything stupid. This, more than anything, will keep you safe.
8 Ways to Increase Your Diving Confidence.
By Polly Philipson
Many people feel anxious before a dive when they are starting out on their scuba diving journey. It is completely understandable as it is a new realm that is being explored. Beginners don’t know what it is going to feel like underwater or if they will enjoy it. It feels like there are so many things to think about to start with. These tips help build confidence that will assist you prepare for your amazing underwater experiences
1 – Professional Training Builds Your Diving Confidence
Years of research and tried and tested techniques have gone into formulating today’s scuba diving courses. Modern scuba diving training has been specifically designed to alleviate stress and slowly build on skills to a point where divers are ready to go out into open water. Organizations, such as PADI, have skills and procedures that divers must learn in sequence – these standards are adhered to by PADI Instructors worldwide. Studying theory, watching videos and learning skills in the pool is followed by practicing in the sea with your instructor. This allows you to slowly develop at your own pace – only progressing when you are comfortable with each section.
2 – Knowing Your Equipment Increases Diving Confidence
During your scuba diving training, you will learn how to set up, adjust, check, and don your equipment. Understanding how your equipment works will give you added confidence and alleviate stress. Making sure everything is fitted correctly and securely, with the help of your instructor or buddy, is very important.
3 – Confined Water Practice Raises Diving Confidence
As mentioned earlier, your training is performance-based, and you will have ample time to learn and practice scuba diving skills in the pool before heading out to the open water. Your instructor will assess your capabilities and allow extra time for practice if needed. Likewise, if you haven’t dived for a while then it’s a great idea to jump back into the pool for a Scuba Review.
4 – Correct Weighting and Buoyancy Assist Diving Confidence
Divers perform weight checks on the surface before a dive to determine that they have the correct amount of weight. You will be taught this during your training. If you are worried when you start your open water dive that you may be under weighted, then ask the instructor to carry spares or have spare weights available at the end of the dive on a descent line. It is a mistake to overweight yourself, as this will make you consume air faster and alter your buoyancy and trim when underwater.
5 – Breathing Techniques Help Diving Confidence
Begin your dive relaxed and calm – give yourself time at the start of the dive to become relaxed with slow, deep breathing. Allow yourself to orientate to being underwater by pausing after your descent. Take time to regulate your breathing, check your equipment and computer, and to signal to your buddy that everything is OK. Then you can focus on having fun and discovering the amazing marine life!
6 – Discuss Diving Confidence
Build your confidence by talking to your instructor and other divers about their experiences. You will find people’s passion and love for the sport is infectious; divers love to share their underwater adventures and knowledge. If you feel nervous before a dive then talk to your instructor or buddy. They will assist you in identifying what is causing your nerves and help you to solve any issues.
7 – Watching Videos
Training agencies such as PADI have videos that complement their courses. They are a great way to see what it is like underwater before you go! Watching videos will prepare you for your first experience by visually demonstrating the theory you have learned. Popular online sites such as YouTube are a good resource for finding footage of various dive sites and marine life.
8 – Relax and Enjoy!
The final piece of advice is to relax, take your time and enjoy. Don’t rush to set up your equipment and work at your own pace when getting ready for your dive. When you rush, you create stress and may not follow the procedures you have been taught. Similarly, don’t rush around underwater – take time to appreciate what nature has created and enjoy the full experience of breathing underwater.
Travel Guide that appeared in Singapore Expat Living
Divers – especially those who are keen photographers – are
drawn to rare underwater sights. Moalboal, in the Philippine
province of Cebu, offers a great opportunity to dive with (and
film) the ocean’s biggest fish and some of its biggest shoals.
Chris White of Turtle Bay Dive Resort tells us more
about these two unusual Moalboal dive experiences.
Photograph by Tim Digger
Let’s start with the big boys. The
entrepreneurial fishermen of Tan-awan
Oslob in Cebu – a previously sleepy
little fishing village just 77 kilometres
from Moalboal – discovered in 2011
that when they fed visiting whale sharks
a daily supply of krill (their natural diet) it
was enough of a temptation to convince
them to stick around. This soon caught
the attention of the international media
and all of a sudden Oslob was on the
world dive map.
The attraction for divers is that they
are guaranteed an up-close encounter
with many whale sharks (mature adults
and juveniles) every day of the year from
a shore-entry dive. The whale sharks are
also accessible to snorkellers and even
passengers in paddle boats operated by
the local municipality.
While fish feeding is a controversial
topic, frowned upon by many naturalists
as it can disrupt the natural behaviour of
fish, the whale sharks in Oslob are well
protected, with strict rules in place for all
divers and snorkellers, and are now the
subject of scientific study.
Moving down to the other end of the
spectrum, for a number of years (with
a few gaps in between) divers in
Moalboal have been able to experience
diving among the swirling clouds of
sardines that have made Moalboal
their temporary home, and provided its
nickname of “Sardine City”.
They started out at Pescador Island but
later, inexplicably moved to Panagsama
Beach, Moalboal, where they swim
just metres from the shore. Not only can
divers witness the countless sardines
swimming in formation with the sunlight
flashing off their scales, but they will also
see the many predator fish attracted by
a free meal – schools of jacks, needle
fish and, occasionally, thresher sharks.
at Sardine City
The family-run Turtle Bay Dive Resort
has 28 air-conditioned rooms set in
landscaped tropical gardens, facing
the bay at Moalboal. Relax around
the lagoon pool, or enjoy a soothing
massage between dives.
Can Scuba Be a Good Workout?
By Jessica Vyvyan-Robinson
Although scuba is technically a sport, for most of us, diving is more about calm than cardio. One of scuba’s biggest attractions is the relaxation it offers, as well as the chance to escape from the frenetic pace of life on land. Most dives require very little physical work once underwater, and so it’s hard to think of scuba as part of a fitness regime. But a day of diving always leads to a good night’s sleep and a disproportionately large appetite, so perhaps we’re expending more energy underwater than we realize. Although diving requires a relatively low level of physical activity, other factors combine to make it effective exercise, which is good news for those of us who would rather spend our time beneath the waves than in the gym.
The conditions of the underwater environment are a considerable factor in scuba’s value as a fitness tool. Although you may not feel as though you’re exercising while diving, the water around you is conducting heat from your body 20 times faster than air, so you must work hard to maintain its core temperature. Even in tropical climates, metabolic activity increases significantly in order to combat heat loss; in cooler parts of the world, the body must expend even more energy to counteract frigid temperatures at depth. Some dives require more physical activity than others — anyone who’s ever had to contend with strong current knows just how tiring swimming against the flow can be. Similarly, keeping up with marine life, attempting to stay in one place for photography purposes, or any kind of underwater activity that involves hard finning results in additional calorie expenditure.
The technique used to fin properly, i.e. from the hip rather than from the knee, is key to strengthening core muscles as well as glute and back muscles, according to PADI’s director of communications Theresa Kaplan. She attributes diving’s toning and strengthening properties to the fact that water is a medium “hundreds of times more dense than air.” Water resistance is instrumental in defining scuba as a valuable form of low-impact exercise. Diving’s low impact also makes it a good alternative to conventional exercise for those with weak or injured joints, as it puts considerably less strain on the body than most land-based physical activities. Diving is therefore not only a good workout for healthy individuals, but also a great form of physical therapy for those recovering from injury. Some scientists even believe that scuba may decrease the time it takes for wounds to heal, thanks to the body’s consumption of concentrated levels of oxygen at depth.
Diving can also aid long-term fitness, as breathing techniques used to improve air consumption teach the body to absorb more oxygen for every inhale. Normally, the body uses only a quarter of the oxygen it inhales, but diving can increase lung efficiency over time. And the dive itself isn’t the only part of the sport that offers a workout. The routine of kitting up, carrying gear to the point of entry, getting in and out of the water and de-kitting also contributes to scuba’s overall fitness value. A dive cylinder weighs between 30 and 50 pounds; carrying a full scuba unit strengthens core muscles, particularly during shore entries. Lifting cylinders, weights and other equipment often involves actions comparable to weight-lifting exercises used in the gym. Diving is therefore not only a cardiovascular workout but a muscular one as well. According to the American College of Sports Medicine, the physical demands of diving are significant enough to be treated with caution; those suffer from significant health conditions or obesity should seek medical advice before attempting to dive.
The benefits of scuba to general physical fitness were acknowledged by the 2011 Compendium of Physical Activities, which compared it in terms of metabolic activity with ice-skating, power-walking and casual soccer. On average, a man weighing 180 pounds can expect to burn as many as 600 calories during an hour dive, and many more if swimming in strong currents or particularly cold water. Several online calculators can work out the calories burned during a specific dive, based on weight and the time spent underwater.
Scuba is beneficial not only as a viable form of physical exercise, but also for mental and emotional wellbeing. The peace, serenity and beauty of the underwater world encourage positivity and give real joy to those who experience them. Diving is a great way to tone and strengthen your body, burn calories and boost your serotonin levels, ultimately making it both a rewarding and enjoyable way to keep fit.
Five Frogfish Facts
Credits to PADI
Frogfish are masters of disguise. Spot one during a dive and you will win the admiration of every diver in your group – especially photographers. Frogfish, a type of anglerfish, have a textured exterior that aids in their camouflage. While they do not have scales, their amazing ability to camouflage themselves serves as protection from predators. Frogfish vary in color and often have unique spines or bumps that change with their surroundings.
Here are some more interesting frogfish facts:
1. Unlike many animals that use camouflage as a defense from predators, frogfish mostly use their abilities to attract prey.
2. Frogfish have a modified dorsal fin that has a retractable lure resembling a shrimp, which is used to attract their prey. If their lure is eaten or damaged it can be regenerated.
3. Frogfish are carnivores. They eat fish, crustaceans and even other frogfish.
4. A frogfish’s mouth can expand to 12 times its resting size. This allows it to catch all sorts of prey.
5. Because frogfish lack a swim bladder, they use their modified pectoral fins to walk, or even gallop, across the seafloor.
There are many fish in the sea that use camouflage, but the frogfish is a real treat to see. Frogfish can be found in tropical and subtropical oceans and seas off the coasts of Africa, Asia, Australia and North America. Next time you take a dive in one of these regions take a closer look at the reef.
Have any frogfish spotting tips? Post them as a comment below…
Get ready for the 2014 dive season
Posted by Natacha Gajdoczki
The 2014 dive season is underway and if you aren’t ready to grab your dive bag and head off for your next exotic location, what are you waiting for? Before you strap on your gear, be sure that you are completely prepared for another season of underwater adventures. It takes more than the right gear to get you ready for everything the water will throw in your direction. Your body must be prepared for rough conditions as well as the physical and lung strength it takes to successfully complete a dive.
Don’t get out of shape during your off-season. Before you plan a dive, get a quick health and fitness assessment to ensure that you are safely taking the plunge. You may not have to be in Iron Man shape, but it is important to not have any injuries or health issues that may affect your ability to dive. Consult a medical professional to give you the green light if you have recently had any changes in health. Diving will give you a good workout, so be sure that your legs, glutes and core are ready for the journey.
Another item you will want to check off your list is your equipment. Be sure that it is in peak condition and ready for use. You may want to have your equipment professionally serviced to ensure its safety. An equipment failure is not something to take lightly and can be prevented with regular service and care. Follow the manufacturer’s recommendations to ensure that your gear will continue working like new with every dive. Finally, if your body and equipment are ready to go, make sure that the skills required are fresh in your mind. Brush up on important information, or even take some courses to learn new skills.
Should I Get A Dive Computer
By: Charles Davis
Dive Computers are a Sign of Dedication
Each diver will have to decide for themselves if a dive computer is a must have, nice to have or a waste of money. Most serious divers swear by their computers but in reality they were most likely diving for quite a while before purchasing their computer. Dive computers are relatively new in the overall scope of scuba diving and will most likely be your most expense purchase, even more than the training and basic equipment. The variety and capabilities of the different computers on the market are staggering. However, before you even start sorting through the different manufacturers and models, you really need to determine do you need one and how great is the need. You learned the dive charts in your training and they have served you well. When you plan your dive, you look up your limits and adjust your plan to ensure that you stay within the safe limits. Before your second dive, it is back to the charts to look at your residual times. When you start doing dives that are a little more difficult to plan such as a multiple level dive, then you can start using the dive wheel. However both require you to stay within the plan. Also they assume that you are at the same depth for the same amount of time that you calculated.
What is a Dive Computer
Before getting to involved with the topic, I think a brief definition should be included. While there are numerous features on different models we will stick to the basics. Technically it a very difficult process. The computer is able to take its own pressure reading and can accurately keep time. Inside the dive computer are what are referred to as compartments. The number varies by model, but they are calculations designed to mimic the effects of nitrogen on different type of tissue within your body: such as fat, muscle, tendons and so forth. Tissue types absorb and release nitrogen at different rates. Every two seconds or so the computer take a pressure reading, calculates the lapse time and updates the compartments. Using a logarithm based on dive tables it calculated and displays your NDL and other information. The computer is calculating on the performed dived not on how it was planned. Computers are not perfect, there are items that affect the absorption rate that the computers can not measure, such as your activity level, the presence of drugs or alcohol in your blood or your level of hydration. The use of a dive computer allows you to maximize your time underwater using real time data while keeping you within a safe profile.
What is Your Normal Dive
The types of dive you do will be a factor whether it is a must have, nice to have or a waste of money to get a dive computer. If you only dive infrequently and at shallow depths then a dive computer may not be necessary for you. A dive at 30 or 40 feet can easily be managed using the dive tables. If you are doing dives around 60 feet but at a single depth then there may be some use for a computer but it is still limited. If the 60 foot dive is also able to be done as a multilevel then you will see some benefits of a computer allowing a little extra dive time. It is not unusual to an additional 15 or 20 minutes to a dive that goes to 60 feet but returns to 30 feet during the dive. Once you start diving beyond 60 feet then a computer becomes a very useful tool.
If you have not used a dive computer yet, I would suggest you rent one for a few dives. Many dive centers have computers for rent. Some center are even making a computer a requirement for deep dives. Deep being defined at below 60 feet. Plan the dive as you normally would but, use the readings from the computer during the dive. Afterward compare what you were able to safely dive with the times listed in the dive plan. This should help illustrate the value of the computer for your diving style.
If you are thinking of getting a computer, project how many dives will you do in a year, also how many of those are deep dives. Also take the cost of the dive computer you are interested in and divided it by the cost to rent the computer. This will tell you how many dives it would take to pay for the computer based on the rental cost. These three number should show you the economic benefits of buying instead of renting.
Dive More Safely
Dive computers have helped many divers maximize bottom times while still staying in a safe range of risk. They are also able to warn a diver that has exceeded his NDL and to provide guidance to reduce the risk with decompression stops. Given the serious injuries that can result from DCS, a dive computer should be considered for anyone who dives near the edge of the dive tables maximum time.
Night Diving Made Easy
By Eric Douglas
Night diving is special because even a familiar site looks different at night. When you make a day dive, you normally scan the entire dive site looking at your surroundings. At night, you see only the area of the dive site that is lit by your light. This forces you to slow down and concentrate on that one area.
Stay close and shallow. Night dives tend to be shallow, so you'll have plenty of bottom time to go slow and take it all in. Colors, for example, are much more vivid on a night dive than they are during the day. It's simple dive physics. If you're making a daytime dive in 66 feet of water, sunlight gets absorbed, stealing away the colors. On a night dive, your light source is never more than five or 10 feet away, so the water doesn't take away any of the light spectrum.
Redefine "night." When the sun is low in the sky, very little light penetrates the surface, making it pretty dark underwater even when there is still a fair amount of light above. Diving at dusk is a good way to start your night diving career. You have the convenience of gearing up when it is relatively light, but get the full effect of making a night dive. On ocean dusk dives, you also have the added benefit of watching the reef creatures migrate through a kind of "shift change" as the day animals disappear and the night animals come out to play.
Get the right gear. You'll need a primary dive light and a backup light. The primary light should be the larger and brighter of the two. How large and how bright? That's up to you, and your choice may vary depending on the clarity of the water. When shopping for a light, try out several as some have different grips and handles to suit your personal preferences. Your backup--or pocket--light should be small enough to stow easily, yet bright enough to help you find your way back home. Most lights designed for this purpose are smaller and typically shaped more like a traditional flashlight. Remember, though, that if the primary light fails and you switch to your backup, it's time to end the dive.
Tie one on. Most dive lights come with a way to attach a lanyard or wrist strap. Get one. It's cheap insurance against dropping and losing your primary source of illumination. Most dive lights are negatively buoyant; if you drop one in deep water it may be gone forever.
Know the signals. If there's one aspect of night diving that is more complicated than day diving, it's communication. You and your buddy should review hand signals before entering the water and agree on the ones you'll use. You have two options: One is to shine the light on your hands so your buddy can see what you're saying. The other is to make signals using your light. You can signal “OK” and “Yes” or “No” by moving your light in a circle, or up and down, or side to side. You can even get your buddy's attention by circling or “lassoing” his light beam and then pulling it toward you. If you've practiced this beforehand, your buddy will know what you're doing.
Should you become separated from your buddy, get vertical and shine your light outward while turning a full circle. Your buddy should do the same and chances are you'll spot each other. If you surface far from the dive boat, point your light at the boat until you get the crew's attention, then shine it down on your head so the crew can see you clearly.
Aim carefully. On any night dive, you should treat your light like a loaded gun. Never shine your light directly into another diver's eyes--you can ruin his night vision.
Go easy on the light. First-time night divers tend to buy the biggest, brightest beam they can find and cling to it like a security blanket. As you gain experience diving at night and get comfortable, you'll find smaller primary dive lights do just as well, particularly in clear water. On some night dives, lights of other divers, the boat and the moon can provide so much ambient light that you may leave your torch off for much of the dive.
If you do need a light, you may not need its full power. Some LEDs have a half-power setting you can use to dial back the brightness. Or try dimming your light by cupping your fingers over it. In any case, you'll see more natural behaviors if you use the edge of the pool of light, not the hot spot, to pick out fish and critters.
One of the unique things about night diving in the ocean is bioluminescence. Some varieties of single-celled plankton give off light when they are disturbed underwater. Your fin kicks or a wave of your hand can create an explosion of undersea sparks, but you'll miss the show in anything but dark conditions.
Do reconnaissance. Before you make your first night dive on a site, you should dive it during the day. This allows you to learn the layout of the site and get comfortable with it.
Mark the way home. If you're diving from shore, rather than from a boat, you should also place lights on the beach. It's a good idea to have two lights close together at your entry/exit point and then a third farther away. This gives you something to swim for after the dive when you're swimming back in.
Making a night dive from a boat brings with it a different set of concerns. The boat should be marked with a flashing strobe you can use to find your way back. When surfacing near the boat, shine your light toward the surface and watch carefully to avoid colliding with the hull.
Have fun! Most important, relax and enjoy the dive. It's natural to be a little anxious before stepping in the dark void of an unlit ocean or lake, but it's also exciting. When you overcome your anxieties about night diving, you get another eight hours of each precious dive day to explore and create new and lasting dive memories.
Underwater Video 101
By: Megan c/o PADI
With underwater cameras getting cheaper and more accessible, many divers have taken a giant stride into the world of underwater video. Here are some useful tips.
Tip #1 Get the right accessories
Don’t use the generic GoPro accessories like the head or chest strap. Strap a camera to your head and you’re bound to get jerky footage with poor composition.
A red filter or a dive light made for photos/video is a must. Call your dive center and get one of these items before you put one toe in the water. If you get a red filter, don’t forget to take it off when shooting topside (see photo below).
A “tray” with a handle will also serve you well. The goal is to get as steady of a shot as possible. Being able to hold a large object with two hands (versus a teeny camera with one hand) will improve the steadiness of your shot and make your video look more professional. Not to mention, a tray with a handle makes for a more secure hand-off to the Divemaster. An extending pole is another useful item as it allows you to get closer to marine life such as eels slowly and from a respectful distance.
Tip #2 Tell a Story
Do you have any goals for the trip? Tell us upfront either as a video testimonial or using subtitles. That final scene with a whale shark, or 1,000th dive celebration will make your video more meaningful.
Collect shots of the boat, your hotel, interesting topside life or interesting buildings. Use these to create an intro montage to establish a sense of place.
Tip #3 Dive and Shoot Within Your Limits
When you’re just starting out: choose stationary or slow-moving subjects. Film tires, coral heads, wrecks, a turtle scratching its butt, etc.
Good buoyancy skills are essential. If your buoyancy is poor, your video viewers will know – your footage will be uneven. You also won’t be able to film interesting creatures that require a slow and steady approach. If you feel the least bit in doubt about your skills, enroll in a buoyancy class (you won’t regret it).
Tip #4 Include Other Divers – Most Importantly Yourself!
Other divers can both make and mess up your videos. If diving in a herd, try to get in front. Divers swimming toward you are more interesting than those swimming away. Bonus: you’re more likely to get the cool critter shot before someone else scares it away.
If you encounter a large critter or sponge of remarkable size, try to film your dive buddy next to it. Lastly, keep in mind the main audience for your video will be friends and family; and to them, you are a star. They want to see footage of you. Have your buddy capture you swimming near some cool marine life, or if you’re diving from a dinghy, go for the back-roll selfie!
Tip #5 Post-production
If you’re interested in some royalty-free music, Youtube has libraries of free music. If your video takes place in another country, ask your dive crew or taxi driver about popular local bands and spice up your video with local sounds.
Less is more! Trim each clip to about five seconds – unless your shot is really, really amazing (like a whale shark or a seahorse giving birth). Aim for a total video length of no more than three minutes. Two minutes is ideal.
If you’ve got a long clip where something interesting happens in the beginning and the end, the best thing to do is to break them up into two clips. If this isn’t possible, break up a lackluster middle section by throwing in some interesting facts or trivia about where you’re diving. This can be done in iMovie or in youtube.