Scientific Diving 02/20/2012
Scientific diving at work can be described as any diving operation undertaken in support of science. Because of this, the tasks undertaken under the scientific code can vary markedly. Below are some examples of diving projects that are typical of those supported through Scientific Diving.
Photography can be used underwater in order to better illustrate an event or process or for more detailed analysis. Traditionally most underwater photography was by film SLR cameras. Increasingly this is being replaced by high resolution underwater digital SLR still photography.
Specimen collection or in-situ measurementUsing divers to collect biological specimens from the underwater environment has many advantages over surface-based collection methods. The use of divers over trawls or grabs is that they are not destructive and also only take the minimum number of specimens required. More advanced collection techniques, such as the use of anaesthetics underwater, allow specimens to be captured, measured, sometimes tagged, and replaced to the exact location of capture. In a similar way, the measurement of some plants and animals can be made in-situ underwater without the need to destroy them through retrieval to the surface.
Examples of studies that have employed advanced specimen collection techniques underwater are:
The presence of divers underwater can disturb or interrupt natural events. In order to construct longer term analyses of events, static underwater video equipment is deployed. The equipment can either store the images self-contained or transmits the images to the surface through umbilicals. The use of time-lapse can prolong the operation; infra-red cameras can record both at night and day. Correct positioning of the cameras by divers is often an essential component of the study. Divers can also maintain the equipment underwater meaning that the apparatus does not have to be come to the surface each time.
Examples of studies that have employed diver-deployed static underwater video are:
Diver-based underwater surveys are often used to quantify biological communities or single species over defined areas. There are advantages and disadvantages to using divers for survey work, and there are many different forms and approaches to conducting the surveys.
Examples of studies that have employed diver-based survey for data collection are:
It is often very difficult to obtain broad scale visualisations of areas of sea bed. If the water is dark then a lot of illumination is required. In the UK, waters are often turbid and so obtaining a broadscale photograph is almost impossible. Video mosaicing employs digital video cameras on a sliding apparatus constructed underwater to maintain attitude and height above the seabed. The camera is moved over the area to be visualised and either continual or individual images taken. The processing of the images takes a percentage of each image and digitally overlays it onto to the previous image. Even though the resolution of a single frame of video footage may not be high, once fully mosaiced, the researcher will obtain a high resolution image of a wide area, irrespective of the water clarity or lighting. An example of a study that has mosaiced video images obtained by divers is:
Benthic cores contain a lot of information about the receiving environment and the impacts on it. Sometimes the cores are taken for pollutant analysis, sometimes to assess the bioligcal community within the benthos, and at other times in order to make physico-chemical measurements on the cores post-collection. The advantages of using divers to core by hand is that they can be precise on where the cores are taken from and the level of disturbance is less than if some form of surface deployed corer was used.
Example of studies that employed benthic coring using divers are:
The longevity of coral reef development and the processes that go into that development make coral reefs ideal sources for proxy studies of the long-term climatic record. The length of core is correlated to the time record and analysis of changes within the core can determine indirectly the climatic conditions at that point. Divers are used to drill into coral heads in order to minimise disturbance and guarantee the quality of the core.
An example of a study that employed coral cores obtained by divers is:
Often divers are employed in support of science simply to deploy, maintain and/or retrieve monitoring equipment underwater. By attaching the equipment to permanent or long-term moorings using divers means that the whole mooring does not have to be lifted each time. If a large surface vessel is required for this lifting process then it can be expensive. Continual deployment and recovery of moorings can impact the sea floor in vulnerable areas.
The example shown is deploying an underwater hydrophone for detecting Harbour Porpoise movements. Other examples are tide gauges (e.g. www.pol.ac.uk/ntslf ), temperature loggers, sediment traps, current meters, settling panels and a whole range of specific underwater experiments.
DIBAYANGKAN SAJA : The right stuff 01/30/2012
Setting off to dive somewhere far away from home, it’s crucial that you arrive at your destination with the right equipment for the conditions you’ll encounter under water. Five divers choose five very different destinations, and we feature the suits and other kit that they select to go with themTHE BAHAMAS
SIRIKIT SNOW HAD HER HEART SET on diving close to sharks, and chose the northern islands of the Bahamas as her destination. To avoid hurricane season, she chose to go in spring.
Sharks are now protected within the waters of this island-nation and close encounters are guaranteed if you attend one of the shark encounter dives operated by most of the dive centres in the north. Mostly Caribbean reef sharks, they can grow to substantial size.
Contrary to popular belief, these islands are not in the Caribbean or even tropical, so the water, cooled by the Gulf Stream, can be parky in the earlier parts of the year.
The sharks come close in this part of the world, so Sirikit needed to cover up well not only against the cooler water but also with thought for a chance collision with the skin of a passing shark.
The Mares Flexa 543 full-length suit combined with Cressi Neoprene boots she chose are an attractive ensemble.
The integrated reinforcement at the knees and shins of the suit would prove useful for protecting the suit from the rough surfaces found under water, as visiting divers are asked to kneel with their arms crossed at organised shark feeds that might be on sand or on the deck of one of the many wrecks intentionally sunk for divers.
The front zip makes it easy to don the suit without help, and the Trilastic construction gives unparalleled comfort.
For fins, Sirikit chose Mares Waves. They are lightweight but have proved in our tests to be among the most efficient, especially at the price.
Her choice of regulator was the extremely high-performing yet very lightweight Atomic T2x all-titanium model, and she matched this with an Atomic Cobalt computer, because she likes air-integration but prefers to see a highly readable display at the end of a hose.
The Cobalt uses an OLED for imaginative use of colour, and there’s no mistaking the information it provides.
With an eye on checked-baggage allowances, Sirikit went for a lightweight Aquatec Aquamarine lamp, with its high output but the facility to stow it easily in the pocket of the Scubapro Equator BC.
She also attached a natty little Halcyon Titanium knife in its sheath to her waistband.
The Equator is a close-fitting conventional waistcoat-style BC with an integrated-weight system well secured by buckles, and a tank camband with a cinch-strap that makes swapping between identical-sized tanks swift and convenient.
Sirikit selected the pretty TUSA Serene M16 single-faceplate mask with matching Imprex snorkel.
The snorkel would come in useful for those times when she wanted to swim around the sandy shores between dives.
She was always nervous about launching her own DSMB, but has found that the Delayed-Aid fitted to a Beaver ratchet-reel takes all the anxiety out of the technique, because it acts as a funnel and automatically releases the buoy when filled.
ALEX KHACHADOURIAN HAD NO weight of checked-baggage to consider, because he was intending to drive to Scotland to dive around the West Coast. For this he chose to take his favourite O’Three Ri-2100 Neoprene drysuit combined with a thermally efficient Fourth Element Arctic undersuit.
The Arctic’s two layers of high-insulation, low-bulk fabric ensure exceptional levels of thermal protection. The drysuit had been made to measure and fitted him like a glove.
Talking of which, Poseidon 5mm gloves would keep his hands from getting chilled, and an O’Three hood would do the same for his head, under an Aqua Lung Teknika mask.
A Buddy Tekwing BC is tough and durable for RIB-diving and gives plenty of maximum lift. Combined with Buddy Twinning Bands, it would give Alex the option to twin up two cylinders quickly and easily should the need arise.
The integrated-weight system takes care of the lead and avoids the discomfort of having it on a separate belt.
Alex’s regulator of choice for this trip was the Mares Navy, a diaphragm type specifically designed for use in tough and somewhat frigid conditions.
Another Mares regulator at the end of a long lightweight and super-flexible Miflex hose stuffed under some bungees of the tank would serve as an octopus rig.
Alex had heard about the superb comfort of the TUSA SF6 split-bladed fins, and thought that they would be just what he needed to propel him through the water, but just to add some luxury and to arouse the envy of other divers, he took along a Pegasus Thruster unit.
This snaps onto a mount that straps to the tank and gives around 45 minutes of relaxing hands-free drive, controlled by a remote switch at the end of a wet-connected cable.
It makes the long swims associated with shore-diving a pleasure.
A Scubapro Galileo Luna computer, with its big, clearly readable display, would take care of his deco and gas management, thanks to its gas-integrated tank transmitter.
A pair of Beaver Aquasnips, mounted high on his BC for easy access, would cope with any abandoned monofilament fishing-line he might encounter in the water.
With weight not a consideration, a robust stainless-steel Kent Tooling ratchet-reel would be used as a bottom-line winder and to send up the Aquatec self-sealing DSMB when the time came.
Similarly, a Green Force Tristar FlexiII lamp could be used in conjunction with an umbilical connection and its separate battery-pack for bright lighting and a long burntime. Alex also chose to take his Scubapro cylinders and weights with him.
MAX EATON WAS HOPING TO dive under the ice, so it was appropriate that he chose a drysuit like the Scubapro Fjord. It’s a conventional trilaminate membrane suit, in that it is constructed from a mix of Nylon and Cordura and has a cross-shoulder zip.
It can be combined with almost any level of warm underclothing to insulate from that freezing water.
Max substituted a Waterproof 5/10mm hood for extra protection against the cold and possibly biting wind at the surface, and wore a cosy Weezle Extreme undersuit and socks, combined with that Icebreaker Merino woollen underwear so beloved of Arctic explorers.
The bright colour might be important for visibility if the weather was poor between dives.
An O’Three Heated Vest would provide for total luxury, and substituting the inflation valve supplied with the drysuit for the special O’Three version easily provided the connection between its battery and the waistcoat in the suit.
Waterproof Mitts were the solution to keeping hands from feeling numb.
With all this insulation providing plenty of buoyancy, Max went for a Bowstone Weight Harness as a means of stowing all the lead he was going to need.
It also meant that he could wear his weights low on his hips to reduce risk of the air
in his suit migrating to his legs and giving him trim problems.
Max wasn’t going to take a chance with a regulator freezing, and decided to use two cylinders as completely independent systems.
For this he chose to take a Hollis SMS100 BC, because it gave him the strategy to side-mount them, so that he could easily access the tank valves.
If one or both regulators should free-flow, he could still access the gas by opening the tank valve each time he inhaled, and closing it again afterwards.
The chance of needing to do this was remote, because he chose two regulators with a massive reputation for coldwater performance, the Apeks XTX200 and Scubapro Mk17/A700.
Both are diaphragm-type designs that are dry-sealed against the environment and have designed-in features that make them especially suitable for this type of diving. Braided Miflex hoses took care of hose routes.
Max chose the huge Aqua Lung Slingshot fins, for their capacious foot-pockets and variable thrust afforded by the integrated silicone springs. An Oceanic Pioneer mask would go a long way towards keeping that part of his face warm.
It promised to be rather dark at depth, but Max would have no problem reading his computer display. The Mares Icon HD’s self-illuminating colour display is among the brightest and most legible of any on the market, and now, thanks to a radio transmitter link, it can be integrated with gas supplies.
A little Hollis LED5 lamp would provide light to see the way without adding much weight to his checked-baggage.
The big McMahon reel s simple and has been proved to be a very effective design, with no tendency to jam when sending up the Buddy self-sealing DSMB.
A BC-mounted Beaver knife was added for safety.
TOM SHILLAKER HAD HIS SIGHTS SET ON THE AZORES. It was a destination that few of his friends had been to, and yet it was only a few hours’ flying time from the UK. He wanted the opportunity to dive on the wreck of the Dori and maybe get a chance to share the water with some common dolphin or even blue sharks.
These islands are in the middle of the Atlantic between Lisbon and Boston, and as such experience quite chilly mid-ocean water of 17-18°C, so keeping warm enough to enjoy a long dive was his priority.
It was a toss-up between a drysuit with a medium layer of insulation or a really effective semi-dry. In the event he opted for the latter, in the belief that a good semi-dry would be less restrictive when needing to swim any distance, and for breath-hold diving with pelagics.
The 7mm-thick Waterproof W2 filled the bill. It was combined with an over-vest, which gave Tom the option to wear it or not, according to how cold or warm he was feeling on dives.
He combined this with Oceanic wetsuit boots.
A Cressi hood was going to keep his head warm.
He easily adapted this to take the Aquatec Mask Connection System that meant that he was never in danger of losing his precious Cressi Big Eyes Evolution mask, with its clear crystal silicone skirt. The Aqua Lung Impulse3 Flex snorkel would clip on easily when needed.
For a regulator, he chose the high-performing piston-type Sherwood SR-1, because it can give high gas flows when needed yet is one of the few piston-type regulators that is environmentally dry-sealed. Useful, because he wasn’t sure how cold or how turbid the water would be.
If he was going to get close to any of the enormous schools of Atlantic triggerfish that frequent the area, he was going to need to be able to swim quickly at times.
Equipped with a pair of Scubapro Twinjet Max fins with spring straps, he was assured that he would be able to deliver the thrust he needed when the time came for it.
The Mares Prestige MRS Plus BC is a conventional design with plenty of surface support, which could be important in those Atlantic swells.
It’s also the least expensive Mares BC featuring the effective integrated-weight system, which meant that Tom didn’t have to pack a weightbelt, and would enjoy the extra comfort the system provides.
Not only that, but it has pockets in which he could conveniently carry a DSMB and plenty of D-rings, so that he could easily clip off a lightweight Lumb Conger reel.
Tom intended to manage his dive with the aid of a gas-integrated Oceanic OC1 dual-algorithm computer-watch, and chose to set the algorithm that brought it into line with the other European divers he would be joining.
Finally, he chose a Fa & Mi Super Ledium 50 lamp for use when looking in all the rocky crevices and under parts of the wreck. It’s bright, but it doesn’t impinge too much on checked-baggage allowances.
FARZI BANTIN WAS ABOUT TO SET OFF across the world for the trip of a lifetime, to dive in the nation-state of Palau in Micronesia. This small island nation is swept by powerful currents and abuts the deep waters of the Pacific Ocean, so encounters with the more spectacular examples of marine life are always on the cards.
Whale sharks, manta rays, and pelagic sharks are frequent visitors, and there are also some spectacular Japanese wartime wrecks to dive.
Even clownfish and their anemones are more brightly coloured than those found in places closer to home.
Expecting warm conditions, a 3mm Cressi Spring wetsuit was all Farzi needed to protect her from the ravages of man-eating plankton and ocean currents.
Overall weight is important. The Apeks Flight is said to be the lightest regulator available, manufactured with an imaginative and innovative use of technopolymers even in the first stage.
With swingeing excess-baggage charges in mind for such a long journey, its choice made perfect sense. Its low weight does not compromise its high performance in any way, and it comes with lightweight braided hoses too.
Similarly, the lightweight TUSA BCJ1800 Voyager BC has a full specification, including an integrated-weight system and loads of maximum buoyancy for surface support, but it weighs as little as 2kg when packed for travel.
Full-foot Oceanic Viper fins are also light but pack a big punch, important when diving high-voltage sites such as Blue Corner or Peleliu Cut in Palau. A home-made reef hook
is essential to allow a diver to stay at the shoulder of a reef without damaging it, but you still need to be able to fin forward those few metres from where you descend against the flow, in order to choose the right spot to hook in.
An especially low-volume Cressi Eyes Evolution mask would be less likely to be dislodged by the flow than a bigger mask, because it has a reduced frontal area.
It’s no time to be groping around for gauges, either.
A Suunto D6i computer-watch sits conveniently on the wrist but has every feature needed for leisure-diving and that includes air-integration by wireless transmitter, so even a pressure gauge becomes redundant.
One of the biggest hazards of diving around small islands affected by fierce currents is separation from your boat.
A Bowstone surface flag makes a surfacing diver easy to spot by a boat-crew even in turbulent seas because it is hoisted on its extending pole.
A long-duration lamp such as an Ikelite PCm2 LED can be used for looking in holes and crevices or in Chandelier Cave, but it also doubles as a second surface safety measure in failing light. It is one of the most compact lamps around, so fits unobtrusively in a BC pocket when not in use.
Farzi took a Kapitol Reef snorkel for use in Jellyfish Lake. Her full dive kit weighed in at only 8kg, which gave her the opportunity to pack clothes for a long trip.
Apeks Flight Regulator Set £499
Apeks XTX200 Regulator £510
Aqua Lung Teknika Mask £50
Aqua Lung Slingshot Fins £100
Aquatec Aquamarine Lamp £78
Aquatec (UK) Mask Connection System £10
Atomic T2x Regulator £1067
Atomic Cobalt Computer £889
Beaver Aquasnips £9
Beaver Delayed-Air Buoy & Reel £70
Beaver Sceptre Titanium Knife £69
Bowstone Surface Flag £17
Bowstone Weight Harness £80
Buddy Tekwing BC £425
Buddy Self-Sealing DSMB £32
Cressi Big Eyes Evo Crystal £57
Cressi 5mm Hood £23
Cressi Spring Wetsuit £149
Cressi Wetsuit Boots £21
Fa & Mi Super Ledium 50 £275
Fourth Element Arctic Undersuit £174
Green Force Tristar FlexiII £525
Halcyon Titanium Knife
Hollis LED5 Lamp £72
Hollis SMS BC & Rig £613
Icebreaker Merino Wool Base Layer £100
Ikelite PCm2 LED Lite £50
Kapitol Reef Snorkel £39
Kent Tooling Narrow Ratchet Reel £92
Lumb Conger Reel £30
McMahon Reel (Large) £40
Mares Abyss Navy Regulator £500
Mares Flexa 543 Wetsuit £200
Mares Icon HD Computer with Transmitter £1070
Mares Prestige MRS Plus BC £300
Mares Wave Fins £69
Oceanic 5 Boots £40
Oceanic OC1 Computer Watch £1152
Oceanic Pioneer Mask £59
Oceanic Viper Full-Foot Fins £23
O’Three Ri-200 Drysuit £949
O’Three Heated Vest £895
Pegasus Thruster Leisure DPD £1300
Poseidon 5mm Gloves £29
Reef Hook (home-made) £20
Scubapro Galileo Luna Computer with transmitter £769
Scubapro Equator BC £299
Scubapro Fjord Drysuit £639
Scubapro MK17/A700 Regulator £499
Scubapro Twinjet Max Fins £99
Sherwood SR-1 Regulator £378 plus £140
Suunto D6i Computer-Watch with transmitter £845
TUSA BCJ 1800 Voyager BC £335
TUSA SF6 Fins £68
TUSA Serene Mask £48
TUSA Imprex Snorkel £16
Waterproof G1 5mm Mitts £37
Waterproof W2 7 Semi-Dry Suit and Overvest £340
Waterproof 5/10 Hood £39
Weezle Extreme Undersuit £172
Cavern diving is the exploration of permanent, naturally occurring overhead environments while remaining within sight of their entrances. It differs from cave diving in that, while cave divers may penetrate thousands of yards, cavern divers generally go no further than 130 feet from the surface. Additionally, cavern divers keep the entrance clearly in sight at all times, and use a guideline so that, should sight of the entrance be accidentally lost, divers can immediately regain it.
By taking these steps, cavern divers remain able to make emergency swimming ascents and, thus, restore the safety margin they enjoy in open water. Properly trained and equipped wreck and ice divers who wish to remain within recreational diving limits take similar steps to ensure they maintain a comparable safety margin when entering their unique overhead environments.
Because cavern divers remain within the controlled emergency-swimming ascent zone, while cave divers go far beyond it, there are several other significant differences between cavern and cave diving.
Because cavern diving is still a form of recreational scuba, with modest risk factors, it is an activity that a number of experienced recreational divers can learn and enjoy. Cave diving, in contrast, is for a far more select group of individuals. Cave divers should possess near-instructor-quality buoyancy control and general diving skills. They should be utterly committed to diving in a highly disciplined and methodical manner and have an above-average understanding of the technical aspects of diving.