Learning to drive a car takes time but it mainly revolves around controlling the machinery. That’s because we all grew up with traffic systems and although we may intentionally or unintentionally break the rules of the road at times, they come as no surprise to us. If we came from a planet from another Universe, things may be different. It might need explaining why having a head-on collision with an oncoming truck whilst attempting to turn across it path is a bad thing. It might come as a surprise that road users and pedestrians on Earth usually have segregated paths.Learning to scuba dive is a little like entering an alien world where some of the important rules that keep you alive may come as a bit of a surprise to you. That’s why it is essential to be properly trained. However, like driving a car, scuba diving becomes as much second nature once you have had enough practice. Diving, you can then enjoy a weightless world just like an astronaut – but it’s not rocket science. You will probably encounter alien life forms – but it’s not rocket science. Elderly? Even if you are old enough to have witnessed man’ first landing on the moon live on television, you can still learn to scuba dive. You don’t need to be supremely fit – and it’s not rocket science. Young? You may be young enough to anticipate working in a space station but if you are sensible and older than ten you can still learn to dive. It’s not rocket science. Scuba instructors get paid very little. They often do it for love of the sport. It can also keep an ego inflated so beware of those that dress up what they teach to appear more complicated than it really is. Although it is wise to do a proper core course with an internationally recognized agency, you can pay for a structured course on most sub-branches of scuba diving technique too but often a little kindly advice or some minimal supervision is all that is needed provided you put in the practice. It’s the same with underwater photography. There are aspects that might not have occurred to you. Taking pictures through water is very different to taking pictures in air because the light acts differently. Firstly, the light is selectively filtered. The deeper you go the fewer rays of red or green light penetrate from the surface. The effect is to make everything look bluer. You will need to learn how to white balance your pictures either when you shoot them or afterwards. In some cases filters that reduce the amount of blue light reaching the camera’s sensor can be the answer. This daylight is naturally always from the top and often lacks contrast. A solution to getting a more interesting lighting is to combine your pictures with light from a flashgun or powerful video light. A little practise with flash and camera settings will allow you to learn how to balance this foreground flash lighting with natural blue lighting behind. You’ll soon work out a combination of settings, which allow you to follow a successful personal formula. The second obstacle to good pictures underwater comes from the fact that natural water is full of tiny life forms. It’s a planktonic soup of tiny animals. That’s why we are often heard climbing out after diving, extolling the virtues of the visibility that might be at 30m horizontally. We call it “Gin clear”. If we had the same degree of visibility whilst driving, we’d call that a fog! The secret to sharp clear pictures is to get close to your subject and then get closer still. This means we are either reduced to taking extreme close-ups of the minutia of life found in the oceans or we need to use extra wide-angle lenses to get all of a larger subject included in the camera’s vision when we are close. It’s not rocket science. Experienced terrestrial photographers who take up diving often wish to apply the photography techniques they are familiar with. They are not used to crowding their subjects and often want to use longer focal-length lenses. However, standing off and zooming in merely magnifies the loss of contrast and sharpness effected by the plankton and detritus dissolved in the water. You would end up seeing through too much water with the consequent loss of quality. Other misconceptions often vocalized by would-be underwater photographers when they first investigate underwater photography is that they will be able to use slow shutter speeds because everything moves very slowly under water. This is far from the truth and thanks to swells and currents the photographer is often moving quickly too. You need to be able to handle you camera smoothly and use a fast shutter-speed for most subjects. The rules are the same whether you are recording live action with a GoPro or taking still photographs with an incredibly expensive top-of-the range DSLR. We are here at Ocean Leisure Cameras to ensure you go away with the kit most suitable for your needs. It’s not rocket science!
Monthly Archives: June 2015
Aqualung Zuma is that little Seaquest 3D, resurrected, re-thought and adapted to include some modern innovations. Without a hard backpack, you can actually roll it up. The Zuma is for the travelling single-tank diver. It comes with an integrated-weight system but only a small pocket. You need to clip your reel and SMB to a D-ring. Not only is it very comfortable to wear but we get reports from satisfied users that because it has such generously padded shoulder straps, it's very comfortable when used without a wetsuit where the water is warm enough for that. If the Zuma is too minimalistic for you, the Cressi Travel Light BC has all the features one might reasonably expect in a conventional BC, including pockets, an integrated-weight system and trim-weight pockets but it is just as lightweight. Trim-weight pockets can be very important to have when using a floaty aluminium cylinder. I’m not the world’s best diver, but during my active instructor days I was happy to demonstrate buoyancy control using an upturned plastic bag in place of a BC. The core function of a BC is very low-tech, so you can be confident that, however much of a compromise the Travel Light might be, it does the job. The otherwise conventional looking Cressi Travel Light is made from a very lightweight nylon material, and has no hard backpack. You can actually roll it up tightly for packing, so it takes up no space, either. It even has an additional Velcro-covered strap to keep it tidy when rolled. It comes with three ways to dump air not including using the oral inflation valve at the end of the corrugated hose. Trying to strap a BC with no backpack to a cylinder by its camband could be very unsatisfactory, but both the Travel Light and the Zuma provide a second strap to stabilise the tank. The cost of a BC like these might well be recovered in excess-baggage charge savings. Don't be misled by divers who say these BCs are too fragile. I've had a Cressi Travel Light in regular use for several years and I ever use it when drysuit diving in colder waters. My wife even used it in Vancouver and in Iceland.Your BC could be the heaviest part of your diving equipment save actual tank and weights. While packing for a recent trip, I noticed that my chosen BC weighed so much that I thought it still had some lead stowed in it. With an eye on my miserable airline checked-baggage allowance, I knew I needed something less substantially made and lighter-weight. A long time ago, before many of you had taken up diving, I reviewed for Diver Magazine, where I was Technical Editor, a little compact wing from Seaquest called the 3D. It was stylish and minimalist. It was like wearing a little rucksack. The one-piece continuous harness meant that one size fitted all. Compared to other BCs available at the time, it was revolutionary. When it came to packing for a flight, it weighed in at less than 2kg. This was in the days when men were men, women made sandwiches, the BSAC ruled diving and every diver had a dual-bag BC, with an independent emergency inflation cylinder, designed for military divers and built to withstand the effects of dropping into the sea from a helicopter (not that they ever did!). My review of the rather feminine little SeaQuest 3D was suitably enthusiastic. It was one of the first bits of kit I reviewed during a 21-year career that genuinely impressed me. I was so impressed that I actually bought one, and have it to this day. It’s also ideal for single-tank drysuit diving. Alas, nobody else then seemed to agree with my findings, and few bought one. It was soon discontinued. Time passed and Seaquest BCs are now marketed under the name of the parent company, Aqualung. Times change. Far more people now see scuba diving as intrinsically linked with travel to tropical destinations, and girls go diving too! Fuel prices have risen in the interim as well, and suddenly lightweight BCs are at last finding their place. The
Travelling back from the Bahamas on a BA jet in the early 'nineties, Rob Palmer, a pioneer technical diver, turned to me and said, "John, I think you should do a Nitrox course.” “Why should I need to do that, Rob? We’ve been using Nitrox now for a couple of years,” I replied.“Yes,” he reasoned, “but I’ve just written a course.” Rob Palmer was one of three early founders of TDI (Technical Diving International), one of the soon to be several technical diving training agencies to spring up in answer to the PADI (Professional Diving Instructor’s Association) successful formula of bringing diving to the masses on a need-to-know-only basis for leisure diving to only 30 metres deep. PADI’s success invariably meant that there would be a group of divers who wanted to go beyond these limits and the successful technical training agencies answered this need. “Give me the exam, Rob, and if I don’t get one hundred percent, I’ll pay you for a course.” Rob passed me his newly written Nitrox examination paper. Alas, it was full of ambiguities in the questions so I went through it with him, rewriting the questions to get the answers he required. I then took the examination and got the highest marks ever awarded in a TDI exam. We were at 36,000 feet! Of course none of this would have been possible without Dick Rutkowski. Dick worked for NOAA in the USA and had made a study of decompression accidents that had happened to leisure divers staying within PADI’s no-stop limits. He concluded that diving could be made safer if the amount of nitrogen in the air we breathed underwater could be in some way reduced. After all, it was the inert gas in the mix that we call air that was giving all the problems. Nitrogen became absorbed by the tissues while the diver was under water and under pressure and if the diver came out of pressure (ascended) too quickly, instead of working its way through the bloodstream to the lungs where it was harmlessly exhaled, it could come out of solution elsewhere, causing tissue damage with crippling and even fatal effect. The smaller percentage (around 21%) of oxygen that we breathe can be metabolised (although we only actually use a small part of that) and caused much less of a problem for amateur divers. Professional divers breathed Heliox, a mixture of oxygen and the rare gas helium, but helium was a very expensive gas that was recycled through the professional diver’s tethered system and recovered back at the surface. Amateur divers exhaled their breathing gas out into the water and lost it forever. Helium would therefore be disqualified on the basis of cost. Dick’s now obvious answer was to increase the amount of oxygen in the air divers breathed, thereby reducing the nitrogen loading. Oxygen is cheap and freely available around the world. He coined the term Nitrox although others preferred to call in SafeAir. He proposed two mixes should be used: Nitrox32 and Nitrox36, according to the percentage of oxygen in each mix. Today, nearly every diver uses Nitrox although the actual percentages of oxygen may vary. However, it is strange to think that not so very long ago, Dick Rutkowski was pilloried for this then seemingly outrageous idea. He was not thought to be credible by the diving establishment of the day. The reason was that during World War 2, combat divers had been equipped with closed-circuit rebreathers breathing pure oxygen with a though-to-be depth limit of only 9m (30ft). Many of them never made it to the shore. We now know that the safe depth limit for breathing pure oxygen over any length of time is only 6m (18ft). Even then, there should be air breaks to avoid lung inflammation. However, oxygen got itself a reputation for being a killer gas for divers and that was how it was portrayed in all the diving training manuals. The amateur diving press vilified Dick Rutkowski for suggesting the use of increased levels of this gas. In 2009 I visited Dick, by now an octogenarian, in his little diving museum on the island of Key Largo, Florida. He still retains copies of all the bad press he got at the time and the wounds evidently still rankle. The editor of America’s primary diving magazine came out and publicly stated he would never use this ‘Devil gas’. Dick countered with articles that said ‘science beats bullshit!’ A lot of emotion was involved. The word ‘oxygen’ spelt certain death to many old divers. They had forgotten that the air they used was actually Nitrox21. Oxygen can be a problem gas under pressure. The human body has a certain tolerance to it and this expires with exposure over a combination of time and pressure. High exposure to oxygen can bring on spasms and epileptic-like fits and should this happen under water it naturally leads to drowning. An operator of a hyperbaric chamber in London reliably informs me that treating patients with 100 percent oxygen to a depth of 18m in a manned chamber can bring on such fits but the incidence is thought to be one in ten thousand cases. That said, increasing the amount of oxygen in a tank of breathing gas is done by degree. Dick was not extolling the use of 100 percent oxygen by amateur divers. He suggested that by reducing the amount of nitrogen, a diver could stay within the confines of the diving tables then in use and be safer. At the same time, Nitrox diving introduced a depth limit. One of the best things to come out of Nitrox training is the idea that air (Nitrox21) has a depth limit (56m) when before some thought there was virtually no limit, and that alone must have saved a few lives. There were hazards associated with Nitrox diving in the early days. Dive centres made Nitrox by partially filling tanks with pure oxygen and then topped them off with air. Handling pure oxygen at pressure is very hazardous indeed and all the equipment must be scrupulously clean including the recipient’s tank and tank valve, something that was not always within control of the filling station. Hydrocarbons present can burst into flames and several dive shops selling Nitrox throughout Europe were burnt to the ground. I later met a gas expert working in the oil industry who told me he’s seen an oxygen installation at a dive centre in the Bahamas that looked lethal. He said the tortuously routed pipework was an accident waiting to happen. Coincidentally, this had been the installation set up by Rob Palmer while we were there! Perishable goods shipped around the world are kept in good condition by removing as much oxygen as possible from the holds of the ships in which they travel. They are kept in an inert nitrogen-rich environment. The increased levels of inert nitrogen and absence of oxygen also reduces the potential for fire. The technology to supply this nitrogen was adopted by the diving industry only instead of eliminating the oxygen from the air, it was the nitrogen that was discarded instead. The system uses two compressors and a membrane and nowadays Nitrox (up to 40 percent oxygen content) is universally produced safely even on dive boats using this denitrogenizing membrane system. At the same time, there was always the risk that filling station personnel might make a mistake and supply a diver with a different mix than the one asked for. It became necessary for every diver to analyse the contents of a tank immediately before using it for diving and simple oxygen analysers became standard issue for Nitrox divers. It became essential to know the percentage of oxygen in the Nitrox mix breathed if accidents weren’t to happen. It is the partial pressure of a gas breathed that is of consequence and at the pressure of depth that pressure increases commensurately. Initially, the technical training agencies all agreed that a maximum partial pressure of 1.6bars was safe and this equated to breathing 32 percent Nitrox at a depth if 40m (130ft), Since this was the absolute limit that PADI divers were supposed to be allowed to go to, it proved very convenient. Nitrox32 became the most popular mix asked for. Once the major agencies realised that this Nitrox diving could be an efficient revenue stream they got in on the act but ever litigation-minded, their lawyers introduced a maximum pO2 limit of 1.4bar that meant a depth limit for a Nitrox32 breathing diver of 34m (110ft), which tied in much better with PADI’s established Recreational Dive Table. In fact, newly qualified PADI Open Water scuba divers are limited to a maximum of 18m deep so using Nitrox instead of straight air simply adds less chance of a decompression event and no other skills need be learned. With the prevalence of Nitrox now supplied alongside tanks of air, there is an argument even for air divers to analyse the contents of their tanks before diving. Very quickly, new tables were written that allowed divers to stay down longer than they might have done had they been using straight air and this safety margin was negated. Divers then wanted bigger tanks containing more gas to allow them to stay underwater longer. At the same time, more adventurous technical divers have taken to carrying a separate tank of a rich Nitrox mix with them, to use in the shallows to speed up staged decompression times. It seems that Dick’s idea has made scuba diving ‘better’ rather than ‘safer’. However, without Dick Rutkowski we’d all still be using plain air. John Bantin is the author of Amazing Diving Stories, available from Ocean Leisure.
Get Your Trim Right . Often, divers carry the right amount of weight but in the wrong place. A drysuit diver needs to carry the best part of his weight in such a manner that his chest will come up slightly and his feet go down. Consider where the fulcrum or pivoting point of your body will be. Integrated weight pockets on a BC might be too high up on a long-legged diver. A weight harness allows weights to be slung lower. On the other hand, a diver wearing a lightweight suit and using an aluminium tank might need to add some weight higher up and, if the BC in use has no trim-weight pockets, you can always add a couple of kilos to the camband that goes round the tank. You need to be comfortably horizontal in the water without any tendency to invert. Deploy a Delayed Surface-Marker Buoy Easily in Mid-water. Why do so many divers make a mess of this? Is it because they haven’t been shown how to do it? Carrying a big camera? Learn how to do it easily with one free hand. Stream the buoy so that it floats above you. A tiny bit of exhaled air in it will help keep it up. Pull off as many metres of line that is practical, so that your reel hangs below you. Take the open end of the buoy and hold it with fingers and thumb above the upper side of the exhaust-T of your regulator while holding your head a little to one side. Have the line passing through but not gripped by your hand. Exhale into the buoy. It will start to ascend. Exhale again immediately releasing your grip on the buoy and grab the reel as it gets pulled up to your hand. Release the line from the ratchet of the reel. Watch the buoy go. Tighten off the ratchet as soon as the line loses its tension because the buoy will have reached the surface. Get Your Weight Right. The human body is more or less neutrally buoyant. Take a big breath and your float. Empty your lungs and your heavy head will go under. If we didn’t wear buoyant kit such as our suits, we wouldn’t need to wear weights. If you want to get your weight right, exhale hard at the surface and the weight of your head in the air should push you down. Add an extra amount of lead to compensate for the weight of the gas you might exhale out into the water during the dive and you’re perfectly weighted. So why do so many divers wear too much weight? Is it because they are used to plummeting to the seabed and trampling around before putting air into their BC of suit to make it back to the surface? Neutral buoyancy is the very essence of pleasurable diving. If you are neutrally buoyant near the surface in your drysuit, you will only need to add sufficient air during the dive to make up for the compression of the air that was in it when you started. If you need to put air in your BC too, there’s a good chance you’ve overdone it with the amount of lead you are carrying. Use Your Lung Volume. Don’t keep fiddling with your BC direct-feed inflation. If you are using conventional open-circuit scuba, varying your lung volume can be a useful adjustment when heading over or under obstacles. A big deep breath will stop you from crashing down lower than you intended and using the range at the other end of the lung-volumes you have available will enable you to cruise over things without inadvertently heading for the surface. You’ll soon find that you can do this almost unconsciously and it’s a great way enjoy a relaxed dive. You’ll also find it helps to keep station at a blue water safety stop. Wear a Suit That Fits. When someone asked me which was my favourite diving suit, I replied it was the one that fitted me best. If your drysuit fits your perfectly, there will be less of a drag when you are swimming. If your wetsuit or semi-dry is too big, cold water will flush around it under the arms and around the groin so that you’ll soon feel cold. If your drysuit is too small you either won’t be able to sit down in it or you’ll be limited to the choice of the undergarment you can wear with it. If your wetsuit or semi-dry is too small, it might interfere with your ability to breathe. Try a suit on before you buy it. That's what the changing rooms at Ocean Leisure are for! We're there to help you.