Monthly Archives: May 2015

  • Getting Back to This World.

    When we scuba dive we enter a different world. We are privileged to see things that ordinary mortals may be totally unaware of. Leaving the shore or the deck of a boat wearing cumbersome kit to be rewarded with that instant feeling of weightlessness is just the start. We swim down and join the undersea domain of fishes and corals, and see shipwrecks and caverns and things that are hidden from those trapped at the surface. It truly is a different world and we can sometimes spend hours down there, it's so fascinating. We can also usually enjoy the tranquility afforded by the watery world below the waves.

    Surface conditions may change while you are diving..
    Alas, the time comes when the reality of decompression time or diminishing air supplies means that this wonderful experience must come to an end (before the next time). We have to rejoin the world to which we really belong - and that is when the cruel reality of life on the cusp between water and air can strike. Where is the boat? The truth is that when we submerge, for all intents and purposes we disappear from those left above. We leave the world we know and those we leave behind have little inkling of where we are. Not only that, but the the surface conditions may be nothing like the tranquility encountered below. It may have been calm when we entered the water but the wind might have strengthened and the sea-state worsened while we were away.
    100-101-2 The deployed surface-marker buoy indicates a diver is waiting below.
    It's important to let those that we depend on to make the transition from the underwater world to the world with which we are more familiar know where we are. A surface-marker buoy is the conventional answer. If you are diving in a strong current you might permanently deploy one at the end of a long line that you can adjust for depth by means of a winder reel. Otherwise you might choose to fill it with air and send it to the surface only when you decide to ascend. In that way it marks where you are while you make a shallow safety stop. Some buoys (DSMB) are open-ended while others come with a constriction at the filling end so that should a tall buoy fall over at the surface, it will not deflate. Of course, such a buoy comes with a dump-valve so that it can be deflated a rolled up after it has been used. Winder reels come in various sizes, each with a ratchet to make handling the line easier. Some divers prefer the simplicity of a spool, which, incidentally is easier to stow in a pocket when carrying it during a dive.
    Diver's Flag Surface-marker flag.
    In some parts of the world that are considered high-voltage diving destinations, places like Cocos or the Galapagos, Komodo or Aldabra, the sea can have large waves as a normal state of affairs so the boat crew will need to be familiar with the route their divers are likely to take. We underwater photographers tend to be an ill-disciplined lot and often end up in less likely spots, especially after being distracted by getting pictures of pelagic species such as whalesharks and cetaceans. We often come up where we are least expected and given that the ocean is a big place, we might need more that a brightly coloured inflatable plastic sausage. This is where the surface-marker flag is a Godsend. The surface-marker flag is deployed on an extending pole made of three sections with an elastic cord running through the centre. It is carried strapped to the diver's tank and can be deployed with one hand when it is needed. (These flags are available to purchase in the Ocean Leisure store on London's Embankment.) Because it can be positioned well above the surface of what might well be a choppy sea and because it is a bright colour in a horizontal shape, it is easily spotted. When I first tested one of these many years ago in the middle of the Pacific, not only did my own dive boat crew easily spot me at the surface, but the crew of another dive boat reported seeing it from many miles away. The other joy is that it is so low-tech. There is nothing to go wrong. Whether you choose a permanent surface-marker buoy, a late deployment surface-marker buoy or a diver's surface-marker flag, a simple brightly coloured device like this will see you safely transitioned from the wonderful underwater world safely back to your boat and the world you left behind. Some British dive boat skippers swear that a black DSMB is more easily seen (also available from the Ocean Leisure store). The choice is yours. Happy diving!Divers with DSMB get into their boat.

  • When it comes to regulators...

    You can rely on our advice at Ocean Leisure because it is based on real world experience...348674 copy 360829 copy 360834 copy 351730 copy 351724 353379 copy 359261 copy 301809 copy 301820 copy 324476 copy 338342 copy 343308 copy 306417 copy 345524 copy 808_tests_oceanic_eos2 copy 1008_tests_mares_prestige copy 68311 copy 57609 copy 91071 copy 103664 copy 103666 copy 30905tests_sept05_01 copy 135187 copy 508_tests_mares_abyss42a copy 0906_tests_08 copy 10404tests2 copy 0406dtest1 copy 0605tests_june_05 copy 0106_tests_05 copy 0304tests4 1205_tests_06 copy 359261 copy 308_tests_scubapro_g250v2 copy 1104tests13 copyA few of the regulators that just one of us has dived with during the last few years! We know what we are talking about. We'll get you what's right for you!

  • Choosing a Regulator

    Scubapro S600 Titanium Scubapro - Good for any SCUBA depth.
    Choosing a regulator can be a bewildering if not a harrowing experience. There are so many on the market, it’s difficult to choose yet it is probably the most important piece of diving equipment you’ll ever buy. After all, it’s what supplies precious breathing gas to you while you are under water and without it you’d drown! There was a time when some regulators were simply not up to the job and I was considered the scourge of the diving industry. I used to employ panels of expert divers breathing from multiple regulators at depths in excess of 50-metres backed up by the scientific record provided by an ANSTI breathing machine to gather data for magazine exposés and comparison tests. Some regulators in those days were not suitable to be taken past 18-metres. That’s all changed. Today, thanks to EU regulations all regulators must perform to a standard (set out in EN250 et al) and so all can provide you with the air you breathe, certainly to the maximum depth you are certified to breathe it. At Ocean Leisure, we only supply the best, but there is still a choice. What tank fitting suits you best, what type of first-stage and what do all those external controls on a regulator second-stage do? There are two basic types of first-stage. The piston-style is usually credited with the ability to give vast amounts of gas when needed while the diaphragm-type is usually preferred for reliable use in water colder than 10°C. Diaphragm-types can also be supplied dry-sealed which makes them especially suited for use in polluted water and they often come with heat-sinks designed in to take whatever little heat there may be in the water to the much colder depressurized gas coming from your tank. When it comes to pollution, remember water can also be polluted with such as fine sand stirred up in rough seashore entry. A-Clamp tank valveDIN tank valveThen there is the choice between International A-clamp and DIN tank connections. The first used to be the most popular and is still extremely popular in the American sphere of influence. The yoke of the A-clamp is offered up to the tank valve that has a replaceable sealing O-ring, and the clamp is tightened to keep it in place. The DIN connection of a regulator so equipped has its own captive O-ring and is simply screwed into the tank valve. Some people swear that DIN is best whilst others say they have trouble doing up the screw thread. yolk-dinThe truth is that both systems work well and nowadays most tanks at dive locations have convertible valves and can be used with both types of connection.
    Dive/PreDive switch and breathing resistance adjustment knob. Dive/PreDive switch and breathing resistance adjustment control knob.
    The second-stage is the part you offer up to your mouth. Some have an adjustment knob on the side. This is used to tighten up the spring on the second-stage valve lever making it use more effort to ‘crack’ open for each breath. It is often called the ‘breathing resistance adjustment’. It does not affect the overall supply of gas. Normally one would leave this wide open but should the inter-stage pressure of your first-stage creep up due to a need for servicing, causing the second-stage to weep air slightly, it can be used to resist that happening, which can be useful if you are a long way from home. Otherwise, I suggest if you want less air you inhale less forcefully! Second-stages for use as octopus rigs don’t normally have this feature. In order to give the user as effortless a breathe as possible, the designer tries to give as clean an air-flow as possible through the valve. They aim to get what’s known as a Venturi effect. As you probably know, the pressure-sensing diaphragm at the front of the second-stage is pushed in by the water pressure and via a lever opens the second-stage valve in such a way that the pressure of the gas inside the body of the regulator matches that of the surrounding water. Alas, if there is a sudden rush of air caused by a sudden increase in ambient pressure, the flow of air can be so fast that the pressure behind the pressure-sensing diaphragm can be reduced rather in the manner of the air passing over the wing of an aeroplane, so that the diaphragm is pulled more than necessary – causing even more gas to flow. The effect is exponential and that is what causes that sudden free-flow so often experienced by divers when the regulator first hits the water.
    Mares bi-pass tube Mares with bi-pass tube
    The solution to this is to interrupt the Venturi effect and this is done either by temporarily positioning a simple vane in the path of the airflow or rotating the orifice of the valve so that the airflow is directed via the internal wall of the second-stage. The control so provided to facilitate this is called the Venturi+/- or PreDive/Dive switch and is found on the side of the regulator, often alongside the breathing resistance adjustment knob. You simply set the regulator control to PreDive or Venturi – before entering the water and switch it over to Dive or Venturi+ once you are submerged. One manufacturer (Atomic) has designed in an automatic depth-sensing Venturi adjustment. Another manufacturer (Mares) uses a patented bi-pass tube as a design solution and no such controls are supplied.
    Apeks Flight Apeks Flight super lightweight regulator.
    The other thing to consider is the overall weight of your regulator. Ocean Leisure has stocks of super-lightweight regulators to suit those traveling by ’plane. Tell the knowledgeable staff what your requirement are and you’ll go away with the ideal regulator for your needs. Some regulator first-stages are entirely made from titanium. It’s an expensive metal but extremely resistant to poor handling and corrosion. Finally, don’t get hung up on mouthpieces. If the regulator you like doesn't have the mouthpiece you like it's usually very easy to swap it for a different one!

  • This Dugong Don't Care!

    Rami had come from San Diego, California, and was tracing his Egyptian roots. He now lived close to Marsa Alam. He often dived along this coast. He knew that a dugong frequented a certain bay. Other divers had seen it but he had only encountered huge green turtles and a few guitar sharks on previous visits, diving from a boat. Now there was a recently constructed hotel on the beach and he and his buddy were land based. They were prepared to spend all week if necessary, searching for the elusive dugong, but there was no need. It might have been a remote bay on Egypt’s Red Sea coast but the presence of the new hotel resort meant things were different. They had been told that they only had to sit on the now crowded holiday beach in their dive kit on and wait until they saw twenty or thirty Italian holiday-makers becoming hysterically frenetic, yelling and screaming and splashing above the dugong, to know where it was. Sure enough, before long a shout went up from one man and all the other people in the water began to swim hastily if not too neatly to where it was. The divers leapt into action, grabbing their underwater cameras and wading out in the shallows until it was deep enough to swim. When they had got out there, they could not believe what they saw. The dugong was in only around three metres (10ft) of water and within easy reach of those prepared to hold their breath and swim down. Above it was an uncontrolled mob, splashing and kicking with dozens of flipper-clad feet bicycling frantically.

    This dugong seemed unpeturbed by the madding crowd! The animal seemed totally unperturbed, lumbering along on its foreleg-like flippers, grazing on the grass cow-like with its capacious, bristly snout and occasionally rising quietly in an almost stately manner through the melee to take a breath of air before returning serenely to the bottom to continue feeding.
    It was the scuba divers that were perturbed. Swimming below the holidaymakers, their cameras were kicked by endless numbers of feet. Their breathing regulators were continually wrenched from their mouths by the wayward limbs of swimmers that hurtled down and crashed into them. They got bruises in places they didn’t know they had. They were having a tough time and wondered why they stayed in such shallow water but the dugong didn’t seem to give a damn. It did have numerous old scars on its back but before you think that ladies manicured nails or jewellery carelessly caused these injuries be informed that male dugongs have tusks that they use in a cavalier manner during the mating season. Not only that, this animal appeared to be quite a clumsy swimmer when it came to manoeuvring. It was a bit cow-like. It’s said that when the wind gets up and waves form in the bay, it had sometimes seen crashing carelessly against the nearby coral reef. Clumsy cow!
    Dugong9556 This picture was shortlisted for the Environmental Photographer of the Year Awards 2015 at the Royal Geographic Society in London.
    It wasn’t a pretty animal either. About the size of a cow and reminiscent of a little underwater elephant from the front, the dugong is a large marine mammal has a wide tail with a fluke not unlike that of a whale. It gives rise to the idea that when sailors from Europe first encountered them and glimpsed them from a distance, carrying their offspring in an arm-like posture of the forward flipper, they may have caused them to first originate the legend of the half-human half-fish, the ‘mermaid’. Dugongs stay underwater for only short periods because unlike other marine mammals, they can’t hold their breath for very long. This is probably another reason why they like shallow water. Many people confuse dugongs with the freshwater manatees of Florida. In fact they look quite different, especially considering that incongruous tail. In fact the dugong looks quite absurd. Who in their right mind would have designed an aquatic elephant with the tail of a whale and the eating habits of a cow? Now if you were to leave a cow to graze in a field there would be plenty of evidence of its passing. You’d have to take care where you walked. There was none of that on the sea grass covered seabed thanks to the voracious activities of the huge and obviously well fed remoras that travelled with it, quietly getting on with the job of cleaning up as they went, a work in progress._FFF2366b In fact life seemed to be carrying on as normal for the dugong. If it didn’t like the madding crowd it would have gone somewhere else. The Rami and his buddy were only relieved when its path of lush sea grass led it down to nine metres (30ft) deep, a place where the raucous revellers above were less able to reach and interfere with them. They then could swim around it without distraction by the sudden rushes from above and unfortunate impacts by unskilled swimmers, and got the photographs of the dugong in a more natural state. At one point Rami lay on the grass ahead of the animal to get a low-angle photograph of it and it lumbered on over him as if he wasn’t there. It was only afterwards they realised that the pictures of this unusual animal with the madding crowd told more of a story. This dugong evidently didn’t care. Give it plenty of sea grass, and don’t bother it. This is a chapter from Amazing Diving Stories, available signed by the author at Ocean Leisure.

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