Nitrox For Beginners
By Jessica Vyvyan-Robinson
Although nitrox has been used for recreational diving for almost 25 years, it is still often misunderstood. As an instructor, I’ve found myself correcting countless students who are under the impression that nitrox enables a person to dive deeper than normal air — just one of the common misconceptions about nitrox diving. Although specific training is required before diving nitrox for the first time, these basic facts will help to make more sense of what it is and what it can do for you.
What Is It?
Quite literally, nitrox refers to a mix of nitrogen and oxygen, regardless of the percentage of each in the mix. The nitrox we use while diving is more properly called enriched-air nitrox, and refers to any blend of nitrogen and oxygen in which the oxygen concentration is greater than that of normal air. This means an oxygen level of 22 percent or higher, although the most common enriched-air nitrox blend is 32 percent. The recreational diving limit is 40 percent oxygen.
What Does It Do?
As every entry-level diver knows, increased pressure at depth causes the nitrogen in the air we breathe to be dissolved into the bloodstream. The time that we can spend underwater is limited by this nitrogen absorption — as we dive deeper and for longer, we absorb more nitrogen at a greater rate. Our no-decompression limit correlates to the amount of nitrogen our bodies can absorb before we must perform compulsory decompression stops or suffer the consequences of decompression sickness.
Enriched-air nitrox slows down the rate at which nitrogen dissolves into our bloodstream, because there is less nitrogen available to be absorbed from the mix that we’re breathing. The higher the percentage of your enriched-air blend, the more nitrogen is replaced with extra oxygen.
There are several reasons divers use enriched-air nitrox. One of its biggest benefits is an increased no-decompression limit, which means longer bottom time. The lower percentage of nitrogen in the nitrox you’re breathing means your bloodstream is also absorbing nitrogen more slowly. For example, on normal air a diver has a no-decompression limit of 50 minutes at 60 feet; using a 36 percent enriched-air mix at the same depth will extend this limit to 130 minutes. In terms of increasing bottom time, enriched air is most useful for depths between 50 and 100 feet; any shallower and no-decompression limits are already so long that divers usually have no need to extend them.
Surface intervals are usually shorter on nitrox as well. Since there is less nitrogen to off-gas, a diver on enriched air will be able to re-enter the water sooner than a diver using normal air after completing the same profile. This also means that divers using enriched air typically have longer maximum bottom times on repetitive dives, and less off-gassing means that enriched air divers are often less tired at the end of the day than divers using normal air. Enriched air can be a valuable safety buffer for divers who choose to use it while following normal air tables, computers, profiles and procedures. Doing so creates a considerable conservative margin that further reduces the risk of decompression sickness, and may be advisable for anyone who may be susceptible to it, such as those who are tired, overweight, older, have suffered decompression sickness before, or are diving with injuries.
Myths, Considerations and Dangers
Although the benefits of diving with enriched air are significant, doing so also involves certain risks. One of the most common misconceptions about enriched air nitrox is that users can dive deeper than with normal air; in fact the opposite is true. Under pressure, oxygen becomes toxic. The percentage of oxygen in normal air (21 percent) only becomes toxic at depths greater than the recreational limit, but the increased percentages of oxygen in enriched air mean that toxicity can become a problem at much shallower depths. Toxicity causes convulsions that put a diver at risk of losing his regulator and subsequently drowning. However, enriched-air courses teach divers how to work out their maximum operating depth using the percentage and partial pressure of the oxygen in their mix. As long as the maximum operating depth is adhered to, oxygen toxicity should not be a problem.
Oxygen also requires caution in the sense that it is an exceptionally flammable gas. Although standard scuba equipment is safe to use with air blends containing up to 40 percent oxygen, the process by which an enriched-air cylinder is filled often involves much higher concentrations. Partial-pressure blending exposes the cylinder to pure oxygen that is later diluted with normal air, and cylinders that are not treated for exposure to such high levels of oxygen can explode. Therefore, any part of the cylinder that comes in to contact with pure oxygen needs to be “oxygen clean,” and cylinders used for enriched air and normal air are not interchangeable. Enriched-air cylinders require decals or stickers to differentiate them from normal ones; they should be serviced annually.
There are a few other equipment considerations to bear in mind when considering enriched-air diving. Before each dive, you are personally responsible for checking the percentage of oxygen in your cylinder. If it is even slightly off, your maximum-operating depth calculations will be too. To check, you will need an analyzer, and although you can usually borrow one from your dive center, it’s a good idea to have your own if you intend to dive nitrox regularly. If you dive with a computer, you need to make sure that yours has enriched-air settings and correlates to the details of your mix before beginning each dive. Remember that enriched air does not improve air consumption, and neither does it give immunity to decompression sickness. Continue to check your gauges, depth and time limits as often as you would when diving on normal air.
With these precautions and the necessary training, enriched-air diving is a fantastic way to get the most out of your diving experience. You’ll spend more time in the water, and less time waiting to get back in.
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.
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.
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.
What not to do when you’re learning to dive
By Shelley Collett