Modified semi-closed rebreather diver course completed in Thailand

Koh Tao, Thailand - Big Blue Tech celebrates the graduation of Andrew Cavell from his TDI Semi Closed Rebreather Diver Course conducted over 4 dives around various dive sites on Koh Tao Island. The TDI Semi-Closed Rebreather Diver Course is designed to teach the student the safe diving and operation of a Semi-Closed Rebreather.

The semi-closed circuit rebreather (SCR) can be manufactured without the use of batteries or electronic components in a very reliable system. It’s only moving parts are the check valves in the mouthpiece and the demand valve override for deep inhalations. It can be simple, useful, and provide many of the benefits divers seek in rebreathers. With the use of Nitrox mixtures, the benefits of EAN use are retained with the added benefits of a properly designed SCR which includes:

• Quiet, reduced bubble operation
• Extended bottom time (due to efficient use of gas)
• Lighter, more comfortable diving systems
• All the physiological benefits of EAN (Nitrox)

Other advantages of the semi-closed circuit rebreather become obvious with use in each dives chosen environment. For example, the inspired air is moist, not-dry, helping to eliminate “cotton-mouth.” Also, the gas is warmer, reducing heat loss in cold-water diving. Buoyancy needs only be set once at depth. As the diver breathes, the system acts opposite to the lungs producing no change in buoyancy from inhalation to exhalation. This takes some getting used to for experienced divers.

Diving on the rebreather is a remarkable difference to normal open circuit scuba. Andrew’s first experience in the shallow training depths was commented as “that’s weird” when referring to the control of the buoyancy using your lungs. Because the unit uses a bag of air that you exhale and inhale from the exchange of gas from lungs to unit is different than experienced in normal scuba. In scuba diving when you exhale you descend and when you inhale you ascend. In a Semi-closed rebreather the movement is opposite.

During the open water dives do depths up to 30m Andrew found the marine life came much closer then ever before and that the air was not as dry as in normal scuba.

The rebreather which was used is a modified Drager Dolphin Semi-closed rebreather which has been adapted from it’s 4 litre tank which provided 69 hours of dive time to twin 6 litre tanks to get the increase gas and dive time while utilizing a full canister of soda lime. This rebreather also features the ability to bolt on a backplate and wing so technical divers can find it more comfortable and streamlined.

The PADI/DSAT Tec Rec blog reports the graduation of PADI Course Director and DSAT Tec Instructor Trainer Rod Abbotson who completed his TDI (technical diving International) CCR Instructor course for the Pelagian DCCCR.

The blog reports that Mark Elyatt, who held the world record deepest dive to 313m, visited Jordan this month to train Rob to be an instructor on the Pelagian Rebreather. The Pelagian Rebreather is manufactured in Koh Samui, Thailand by Big Blue Tech Samui former Manager Andy Fritz who is owner of Rebreather Lab.

TDI - Technical Diving International is the leading certification agency for all things relating to technical diving, rebreather diving and related courses like scuba technician certifications. Currently DSAT/PADI have only Semi-Closed rebreather courses in their technical curriculum but rumors swirling in the community  indicate a change to introduce a course based on the Poseidon Discovery rebreather in 2010.

More on this event can be found on the Tec Rec Blog and on the Dive Aqaba Website

A typical Self-Contained Underwater Breathing Apparatus, or scuba gear for short, usually consists of a tank containing compressed air and a mouthpiece used to regulate the flow of air from the tank into the lungs. But breathing air in this manner is extremely inefficient, especially while considering the applications of this particular apparatus. This is because the air you breathe out still contains a fair amount of oxygen.

Modern scuba gear use rebreathers to filter out the exhaled carbon dioxide gas and gather the oxygen, to recirculate it until it is consumed. By doing so, the underwater breathing process becomes more efficient, allowing professional divers to remain submerged for a longer time.

Basically, a rebreather has three roles. One is to remove the carbon dioxide gas from the exhaled air. This is done by pumping it through a chamber containing sodium hydroxide, which reacts with the carbon dioxide and forms calcium carbonate. Secondly, the rebreather must complement the amount of consumed oxygen with fresh one from the tank. The oxygen tanks may contain either pure oxygen or oxygen mixed with either nitrogen or helium.

Alternatively, the rebreather must control the oxygen concentration inside the breathing loop after the exhaled oxygen is combined with fresh oxygen, for an optimal oxygen delivery sequence.

Types of rebreathers:

Currently, there are three types of rebreather systems commercially available - oxygen rebreathers, semi-closed circuit and closed circuit ones. The oxygen rebreathers make use of pure oxygen tanks as the only source of breathing gas. They are generally disadvantaged by the facts that they cannot be used in decompression depths and may pose oxygen intoxication risks.

Semi-closed circuit rebreathers on the other hand, carry tanks containing oxygen mixed with another gas - nitrogen, helium - and enable divers to surpass decompression depths without any risk of suffering from oxygen intoxication. Closed-circuit rebreathers are a combination between the two, using both pure oxygen and oxygen mixed with various gases.

Besides being highly efficient in making use of the gas carried by a diver, rebreathers are also lighter than any other conventional scuba gear. The normal concentration of oxygen inside the atmospheric air is about 21 percent, while that of nitrogen is 78 percent. Since nitrogen is not as critical as oxygen, almost three quarters of the gas carried in conventional scuba tanks is dead weight. Also, less nitrogen is circulated through the system with the help of rebreathers, thus the effects of decompression are reduced to minimum.

Because they recycle oxygen and carbon dioxide is filtered through sodium hydroxide, very little or no gas is ever pumped into the water to produce the characteristic bubbles.

Source

Ambient Pressure Diving has become aware of a potential issue if the diver operates hydraulic equipment underwater.”It has been brought to our attention that when operating some hydraulic equipment underwater, there is a possibility of inadvertent, Vision handset, button operation and extra care must be taken to monitor the rebreather display at more frequent intervals.

Specifically, whilst assisting in the operation of a Jack hammer / road drill underwater, the percussion exhausts will have sufficient force, frequency and focus to press the buttons when within 2 feet (60cm) and when facing the percussion exhausts.

In tests, the button operation is random and this switching can cause a setpoint change or cause it to go in and out of OC mode and/or make any number of changes within the underwater menu including gas options, HUD brightness, LCD contrast, backlight, diluent gasses and bailout gasses. While either oxygen controller can be turned off and on, it is not possible to turn both oxygen controllers off simultaneously while deeper than 1.2m/4ft, providing there are two good batteries fitted.

We have been unable to reproduce the inadvertent button presses with normal diving applications. Tests include tap and fast water movement including moving handsets through water as fast as possible, diving in Rivers and tidal current, scootering, jump tests from various heights and various angles and we can state that inadvertent button pressing is highly unlikely.

The fact is we didn’t get any inadvertent button presses in any of these tests. Furthermore, this is not a problem for the diver holding the handles of the jack hammer, the problem exists for the diver assisting if he works lower down near the percussion exhausts. A diver anywhere at these levels within 2 feet is directly exposed to the water jet, on any of the 4 sides. If the hand set is either at chest level or on the wrist, as long as it’s in line with the jets, the percussion water jet may affect it.

Ambient Pressure Diving would like to take this opportunity to re-iterate to all rebreather divers the importance of looking at the PO2 displays regularly and draw your attention to the key waypoints during a dive where it is essential to monitor the PO2.

The booster rocket used in the Ares I-X test flight was found to be badly dented when divers located it in the Atlantic Ocean.

One of the three 150-foot-wide parachutes designed to gently lower NASA’s Ares 1-X first stage booster to the Atlantic Ocean after a dramatic six-minute test flight Wednesday deflated after deployment, officials said Thursday, resulting in a harder splashdown than expected.

Photographs taken by the recovery crew show the four-segment shuttle booster floating upright in the Atlantic Ocean shortly after splashdown. An initial inspection, sources said, revealed the sort of paint blistering that is typically found on shuttle boosters, along with an area of apparent buckling in the lower segment.

The test of the new parachute system was one of several major objectives of the Ares 1-X test flight, intended to generate data needed to perfect the design of NASA’s planned shuttle replacement, the more-powerful Ares 1 rocket.

While the 1-X test version featured a less powerful first stage booster and a dummy upper stage, it weighed roughly the same as an Ares 1. The full-scale parachute system used for its first flight test was designed to handle the heavier weight of the Ares 1 and its fall from a higher altitude.

A NASA spokeswoman said late Thursday the test rocket’s drogue parachute, used to slow and stabilize the vehicle before the main parachutes are released, deployed normally. All three main chutes then released and began inflating as planned in a two-step procedure. Two of the mains apparently inflated fully, but the third collapsed.

A source said the deflated parachute contacted one of the others as it whipped about in the wind, causing a partial deflation. That could not be immediately confirmed, although a splashdown in that condition might explain the buckling seen in the lower segment of the rocket’s case.

Shuttle boosters, which are lowered to the ocean by two 130-foot-wide parachutes, can be damaged depending on the impact angle and sea state, engineers say. But it’s not yet known what caused the problem with the Ares 1-X booster.

The 327-foot-tall Ares 1-X was launched Wednesday from complex 39B at the Kennedy Space Center. The major goals of the unmanned test flight were to collect engineering data on how the tall, slender rocket flew through the dense lower atmosphere, how the structure responded to aerodynamic and acoustic forces and how the new parachute system, scaled for the planned Ares 1 rocket, performed.

The first stage boosted Ares 1-X to an altitude of about 25 miles and a velocity of 4.5 times the speed of sound in two minutes of powered flight. Explosive charges then fired to separate the spent first stage from the dummy second stage and small upward-facing rockets fired to pull the first stage away.

In a surprise, the upper stage went into a slow, flat spin instead of continuing upward on a nose-forward trajectory as expected. A moment after separation, another set of small rockets fired as planned to put the first stage into a similar spin to prevent a nose-down re-entry that might interfere with parachute deployment.

The two stages appeared to come close to each other as they tumbled, but that could have been an illusion due to the viewing angle of a long-range tracking camera.

The behavior of the first stage appeared normal during powered flight and after separation. A drogue parachute, used to slow and stabilize the rocket before main parachute deployment, could be seen in video from the rocket, but the on-board views cut off before the main chutes could be seen.

Recovery crews consisting of closed circuit rebreather divers and technical divers are expect to finish towing the big rocket back to a processing facility at the Cape Canaveral Air Force Station early Friday. Engineers will be standing by to remove an on-board data recorder that is expected to provide a wealth of information about the rocket’s performance.

Friends of the Singapore National Eye Centre specialist who died in a diving accident on Saturday said he was feeling well before the accident.

One of the divers who tried to resuscitate Dr Marcus Lim recounted the tragedy.

Dr Lim was passionate about photography and he was able to combine this with his love of diving to stunning effect.

On Saturday, he was diving near a shipwreck in the South China Sea. He was honing his skills in preparation for a diving expedition to Antarctica in 2010.

A friend who was there said Dr Lim, who was feeling well before the dive and went down with a group of three others under calm sea conditions, experienced some difficulties after 23 minutes underwater. He was brought to the surface and lost consciousness.

Jay Siak, dive buddy of Dr Lim, said: “CPR was commenced, and the boat set sail for the nearest hospital which is Mersing Hospital. But despite four hours of CPR, we could not revive him.”

The keen sportsman and Liverpool Football Club fan was described by family and friends as level-headed and a loving father.

Heather Lim, a friend of Dr Lim, said: “When we first heard the news, I was completely devastated - just sat up on my bed and started crying. Such a great loss. Such a lovely person.”

Dr Lim leaves behind a three-year old son, Jayden, and his pregnant wife Christy who declined to be filmed. Their baby boy is due to be born next month and Dr Lim had already chosen his name - Tristan

Dr Marcus Lim, 37, was using a device called a rebreather and breathing a mix of gases called trimix - nitrogen, oxygen and helium.

rEvo Rebreathers is extremely pleased to announce that it received confirmation that the rEvo III fully complies with prEN14143:2009, the basis for the (future) new rebreather standard EN14143:2009.

The EN14143:2009 will be the successor of the EN14143:2003, and is sent out to the national technical committees for inquiry. (which means that from that moment it can be used for certification.)

The compliance to the new rebreather standard is for both the manual version (mCCR) and for the automatic version (hCCR), in both sizes (standard and mini)

As soon as the last tests and certifications of some components (the tank valves and pressure gauges) are validated by the notified body, the Certificate will be issued.

Latest, starting January 1st 2010, rEvo Rebreathers will supply CE type approved units directly to the European market.

This result is obtained after more then 2 years of work, testing, developing, large investments (the rebreather testing facility), but also thanks to the feedback and support of our customers.

rEvo Rebreathers will continue to develop and support their customers.

Technical Diving International™ recently announced an agreement with Poseidon Diving Systems, to offer certification on its revolutionary Cis-Lunar Mk VI aCCR, and is offering active CCR instructors the opportunity to upgrade their teaching credentials to cover the automatic, sport-level unit. Instructor upgrades scheduled for NEC Birmingham Dive Show, and DEMA.

“The process is as simple as the unit itself is to operate,” says vice-president of training and membership services, Sean Harrison. “Any active, Closed-Circuit Rebreather instructor can attend the one-day workshop and earn his or her Discovery [Cis-Lunar Mk VI] instructor certification.”

Harrison explains that the unit is aimed at a whole new market and is quite different to ‘mainstream’ closed-circuit rebreathers.

“Poseidon’s Discovery is a remarkable design,” Harrison says. “And the design is the key to our members currently teaching CCR to be able to upgrade to teach it with a minimum of fuss.”

The Mk VI offers all the features of CCR over open-circuit – extended dive times, quiet operation, warm, humid breathing gas, and delivery of ideal gas mixes during all phases of the dive. But the real attraction of Poseidon’s Discovery CCR centers on its ease of use and automated pre-dive tests and operations. It is the simplification and automation of the unit prep and operation that will appeal to sport divers; people who have considered CCR diving but have been put off by their perception that it is complex and not worth the effort for dives within sport diving limits.

The pre-dive procedures for Poseidon’s entry into the CCR market is no more complex than preparing open-circuit gear, due to the pre-packed canister and the Mk VI’s ability to perform all pre-dive tests automatically; from checking gas volumes and loop pressure tests, to calibration of its redundant oxygen sensors. Procedures during the dive are equally simple due to automated operation and no option to “fly the rig manually.” In the unlikely event of any failures in the automated systems, the unit bails out to open-circuit mode.

“The unit promises to bring all the benefits of CCR diving to the avid sport diver, someone who is interested in new concepts in diving but who is less focused on the technical side of things than the average CCR diver has been up to this point. We feel the Discovery will help to open up the CCR market more than any other unit on the market today.”

TDI will be offering upgrades through hands-on workshops to active CCR instructors and instructor-trainers at NEC Birmingham Dive Show, DEMA and other shows and special events in the coming months.

Below is our schedule for the upcoming season for technical diving trips with our Khao Lak office.

You can read more about the vessel here

At 35 meters in length, the Pawara is by far one of the largest boats cruising in the Similans. Her all steel construction makes her safe and smooth, promising a relaxing ride throughout your trip. Each of her 10 double cabins features its own sink, toilet and shower for the ultimate in privacy and convenience. Each cabin also has its own air-conditioner, so you can adjust your cabin just how you like it. Each cabin also has multiple 220v outlets so you can charge your cameras, laptops, or other diving accessories. The Deluxe rooms also have work desks and chairs for the avid underwater photographers.

Due to her massive size, most guests find themselves spending the majority of their time between dives in the expansive common areas of the boat. There is a spacious lounge with a large flat-screen TV, a DVD player and a wide selection of DVDs available to suit most tastes. There are also several desks in the lounge with 220v outlets for those wishing to do photo or video editing on board.

For those who prefer a quieter form of entertainment between dives, you can borrow a book from the on-board selection in the lounge and relax on the sun chairs of the large upper deck, or in the outside lounge on the main deck.

The Pawara features indoor and outdoor eating areas, each large enough on its own to accommodate all customers and crew for meals, so no matter what mother nature has in store everyone will be able to dine in comfort. And the excellent food prepared by our experienced cooks will ensure your meals are as good as your dives.

Big Blue diving has been offering the highest standard in Thailand diving since 1991, and the Pawara only furthers this reputation for quality service. Our multi-lingual staff on board is able to speak English, German, Swedish, Danish, Norweigan, Dutch, Flemmish, and Japanese. If you have language requirements beyond these, we can accommodate just about any request. All of our staff have years of experience in the Similans and even longer track records for keeping divers safe season after season.

Pawara’s large dive deck in the rear of the boat gives you plenty of room to set up and get in. Our on board nitrox system allows nitrox ceritfied divers to extend their bottom times with enriched air mixes. For those not Nitrox certified, we offer Nitrox certification on board, along with other courses such as deep specialty and photo specialty. Dive groups are maximum of 4 people (unless a group booking prefers to all dive together), and your gear is washed and your tanks are filled for you by our highly trained staff. Standard and DIN tanks are available on the boat.

For those traveling with non-divers, we invite you to bring them along as a snorkeling guest, or sign them up for their PADI Open Water course, which can be completed entirely on the trip. We can even arrange to complete the first day of Open Water training in the pool just before the trip to maximize your dive time out at sea.

The Pawara is equipped with a full first-aid medic kit, as well as medical grade oxygen for emergencies. All of our staff have current first-aid certifications.

Pawara has 3 levels of cabins:

Standard rooms are on the lower deck and can be arranged as twins or doubles. These rooms each have a sink, toilet, hot shower, plenty of storage space and 220v outlets.

38,800b per person for Divers

Deluxe rooms are on the main deck and are all twin beds. These rooms have larger windows and have large desks and 220v outlets and are therefore ideal for underwater photographers. These each also have a sink, toilet and hot shower.

39,800b per person for Divers

Master cabins have large windows all around for the best views. These rooms can be made as twins or doubles, have 220v outlets, and have larger bathrooms equipped with sink, toilet and hot shower.

40,000 per person for Divers

*Prices include technical dive leader, technical diving equipment and all gas

Rates are per person, based on double occupancy cabins. When possible, we will allow individual customers to have their own room. However during busy times we may need to put 2 individual customers in the same room. If we need to combine individual customers in cabins, we will only do male-male or female-female pairings for reasons of privacy. If you require your own personal cabin, we offer it at a 40% surcharge. Private cabins are not available during Christmas and New Years.

Couples traveling with small children may be able to have the child sleep on the private couch in one of Pawara’s master cabins. We do not recommend bringing infants on board for many reasons. If you still chose to do so, we insist that one parent stays with the child at all times. In cases like this, you may pay for one diver and one non-diver and simply alternate dives with your partner.

Every person diving in the Similans in required to pay national park fees in cash at the time of the trip. We will collect these fees from each passenger on our departure day so they can be paid upon our arrival in the Similans. please make sure you have 1600b in cash on departure day.

We have diving equipment available for rental, or we can order equipment for you through our suppliers (at a 10% discount!) and have it ready for you upon your arrival. A complete set of equipment is 500b per day. Email us if you have specific requirements or would like to see a list of equipment available for purchase.

Other than that, everything else is included in your trip except alcoholic beverages, available throughout the trip and paid for on the last day.

*CCR and SCR support available with O2 boosting and on board DiveSorb.

Today Big Blue Tech celebrated the successful completion of a TDI Advanced Nitrox Course for Ash, Matt and Andy.

The students come from different backgrounds and environments. Matt is a oil and gas worker based in Kazakhstan but frequents Thailand; he completed his SDI Solo Diver course last month and has come back for more serious diving. Ash is a Divemaster Intern with Big Blue and will soon move up to join Big Blue Tech in December. Andy comes from Denmark where he is actively serving in the Danish Army as a Sergeant and this is his break before returning home for overseas deployment.

The TDI Advanced Nitrox course is based on familiarity with technical diving methods and equipment, buoyancy, oxygen handling, mixes of nitrox above 40% and extended depth to 40m. Some of the highlights of this course included some wreck diving at Japanese Gardens, some cavern diving at Green Rock and diving with Bull Sharks at Chumphon Pinnacle.

Some of the students will continue on to Decompression Procedures which teaches the methods behind decompression diving and more advanced skills while others would continue to gain experience or return home.

In addition, Christos was awarded the TDI Semi Closed Rebreather rating after completing all the skills and requirements for the rebreather and accompanied the course for more experience and training on the rebreather.

Big Blue Tech have been rebuilding a Drager Dolphin Semi Closed Rebreather in an attempt to create a Semi Closed Rebreather that functions and resembles the Halcyon RB80

The Drager Dolphin SCR always had some draw back that kept it from being respected amongst the more adventurous divers:

1. The in water trim was terrible;  The breathing bag or counter lung was located in the top of the unit and the steel cylinder slung in the bottom which made the diver very vertical, almost like a baloon with a weight tied on to the bottom. Additionally the bail out cylinder was mounted on the side making it unbalanced even if you did get vertical in the water.

2. The blue “Commando” bcd wasn’t black.

3. The white box that held the breathing bag wasn’t black

4. The small steel cylinder wasn’t big enough and a larger cylinder would only make the unit worse.

5. There was no way to mount deco or stage tanks.

6. The BCD was restrictive and could not be used with a backplate and harness.

Our initial purchase of a used unit in thailand gave us everything we would need including the oxygen sensor for our pp02 display. Out of the box, the unit was working perfectly with all the tests passed and no leaks.

Our first goal was to remove the old and restrictive built in bouyancy compensating jacket to allow the installation of a backplate and wing mounting system. This mounting system from V4Tec would allow all technical diving backplates and wings to be fitted in the same manner you fit diving gear to twin tanks.

The mounting system and side by side tank brakets arrived and fit perfectly. This alteration improved trim, bouyancy immediately. With the twin 6Lt (S40) cylinders mounted side by side it was difficult not to be balanced and horizontal.

The final and most dramatic improvement was the flexible manifold. Contacting our friends in Pattaya who own an engineer shop, we were able to source the high pressure hydraulic hose along with the fittings for our cylinders. This would give us redundancy and increased gas volume. We would still carry a bailout but that could be slung from the harness.

The testing later moved into shallow water trials where different divers of different skill levels went for a short dive to test the trim and overall experience. While this would be their first time in a rebreather they found it quite easy to reach neutral bouyancy and effective trim. The divers practiced bail out techniques  and general rebreather loop use.

Open water ocean trials will be conducted in the near future to test exposure limits and functionality in saltwater.

Rich Stevenson, 39, is a professional diver living and working in Plymouth. For 10 years he has owned and run dive-boats and, until recently, a coastal dive centre. His independent company now concentrates on rebreather training, underwater film operations and commercial diving charters on his new 9m RIB Ocean Venture. Involved in technical instruction since 1995, Rich was one of the UK’s first IANTD Cave and Trimix Instructors, and is an IANTD and PSAI Instructor-Trainer

I have been privileged and lucky enough to be involved in some of the most advanced and exciting dive projects in the world. My gear has developed alongside these expeditions, and certain equipment was even designed for specific projects.Everything I use has been tested, from the extremes of flooded French caves to 160m-deep wreck dives way offshore in the Atlantic. I have to put total confidence in my kit and, while I still wonder if that kit is the best it could be for my diving, it’s probably as close as it needs to be.

REBREATHERS
I am fortunate to have access to eight units, but number one choice is the CCRB Sentinel, followed very closely by the AP Diving Evolution Plus.Both are made in the UK, which makes using them that much more satisfying. The APD unit has been involved in more expedition dives than any other unit I know, and in 2001 I took a standard Classic Inspiration on the first-ever dive on RMS Carpathia, which lies in 160m - praise indeed! The Sentinel became the solution I was looking for last March, because having a back-mounted rebreather made handling large numbers of stage cylinders so much easier. The work of breathing
and advanced features makes it a firm favourite with advanced divers. I have been known to use a Megalodon on demanding cave and/or overhead-environment dives. The lack of a CE mark makes it impossible for me to use it commercially, but it’s a formidable unit that is incredibly reliable and well-made.

DRYSUITS
I have used only one type in my career, an Otter Britannic Telescoping Torso suit. I have never been
a fan of neoprene suits. Even the crushed type all seem to suffer from buoyancy loss at depth.
Most students I come across on courses seem to be underweighted on the deco phase, and heavier at depth. The membrane variety from DUI and Otter don’t suffer from this, so I find buoyancy control much easier.
Warmth is not an issue if you layer up correctly, and with the layering system you can make the membrane suit far more flexible in temperature extremes. My Otter has been in 26°C water while decompressing on the Britannic, and 1°C water in Finland. It’s only the undergarments that change.

UNDERGARMENTS
With pants in mind, let’s move on! I mostly use Fourth Element thermals, a combination of standard Zero Therms under a set of thicker Arctics for most UK summer diving and dives up to three hours’ long.
For longer dives, a C-Bear undersuit goes over the Fourth Element gear to keep the heat in. A heated undervest may come out, but it’s got to be really cold for that! I’ve found that the Otter “double hood” system keeps my head incredibly warm, and the water trapped between each hood actually warms up during the dive, like a good-fitting wetsuit. I also use Swedish Navy dry gloves. I have holed these only once in 18 months, testament to their incredible toughness.

BAIL-OUT CYLINDERS & REGULATORS
Ally stage cylinders are the only type that work for me, and I have nearly 20 different ones of between 5.5 and 11 litres. The job dictates what I take, but every cylinder will use a Poseidon Cyklon regulator with 1.2m hose, to make emergency gas-sharing stress-free. Each regulator also has a low-pressure inflator hose, allowing me to inflate lift-bags, counter-lungs, drysuits and even my wing if necessary. There is also a 15cm hp hose with SPG on each reg set.

DIVE COMPUTERS/SOFTWARE
Since 2003 I have used a VR3 with the VPM upgrade in support of a decompression software program called GAP. Most modern rebreathers have in-built software, so the VR3s and more modern VRX from VR Technology are used as back-ups to the onboard information. Modern technology can’t be 100% reliable - though it generally is - so I still take a standard Uwatec depth gauge and underwater wet-notes for back-up deco information.

DIVER PROPULSION VEHICLE
I prefer the Silent Submersion N-37, the ni-mh-powered version of the tried-and-tested UV-26
lead-acid scooter, which is favoured by serious cave-divers worldwide. The N-37 is a compact, reliable unit giving more than 90-minute burntimes, with a proven depth rating of more than 150m - more than good enough for me! It may not be the most technologically advanced scooter, and certainly isn’t the fastest, but it has a deep wreck- and cave-diving track record that other units will never have.

ANCILLARY EQUIPMENT

Salvo and Halcyon HID torches provide primary lighting, while Halycon Scout torches provide back-up. Dive Rite reels have always been my favourites, and I use the free-flowing spools for DSMB deployment.I use the low-pressure hose inflating style DSMB in red for drift decompression, with the same in yellow in case of emergency.

Finally, forward propulsion when not using a DPV is by a pair of 10-year-old Scubapro Jetfins, and the ability to see under water is made much easier by a Scubapro frameless mask, also nearly10 years old.

Holding the world record for distance travelled in underwater caves as well as being the first person to cave dive in an Antarctic iceberg, Jill has been at the top of her game for 20 years.

Expert at traversing pitch-black freezing tunnels, full-time cave photographer Jill carries up to 300 pounds of equipment with her on each expedition.

Using technology more advanced than average scuba diving gear, the Florida based adventure cave diver makes use of electric heated wetsuits and unique carbon dioxide recycling aqua-lungs.

“The images of me with my team from Antarctica still bring back the excitement of that unique expedition,” says Jill, who lives in the much warmer climate of High Springs in Florida.

“That was a National Geographic jaunt to the B-15 iceberg, which at the time was larger than Jamaica.

“The aim was to become the first people to cave dive in an active iceberg.

“To say that it was fraught with danger is an understatement.”

The 2001 trip was denied endorsement by the United States National Science Foundation because they deemed it too dangerous.

As a result they had to travel under the flag of New Zealand whose government accepted the risk of the party

Travelling the 12 days by boat from New Zealand to the Ross Sea area, Jill and her team including National Geographic photographer Wes Skiles entered the dramatic caves.

“The thing with the iceberg was that it was constantly moving,” explains Jill who works as a professional photographer and filmmaker in Florida.

“Entrances and creases were opening and closing as the iceberg went through the motions.

“What didn’t help as well was the -1.2 degree sea temperature, that was something else.”

Usually carrying up to £30,000 of torches, cutting tools, rope, special ‘re-breather’ aqualungs in triplicate on her cave journeys, Jill’s motto is to never be unprepared.

Due to the delicate nature of cave diving even a series of bubbles released from her aqua-lung could cause rocks or ice to dislodge and trap her.

“The most obvious thing that could go wrong is to get stuck, in the dark and without any idea which way you are facing,” says Jill.

“It sounds glib, but do not panic. If you do you increase your chances of dying dramatically.

“It is a real test of mind over matter.”

Stunned by her experiences in the pristine, unexplored Antarctic, Jill’s fame in the cave diving world has grown since the mid 1990’s.

“I have been scuba diving for twenty years, but when I broke the world women’s record for distance travelled underground, underwater, then my career really took off,” says Jill.

“I pushed 10,000 feet in a lateral movement 300ft down in the Wakulla Springs cave complex in north Florida in 1998.

“I was experimenting with a 3-D mapping device that cost the best part of £470 million.

“It is the technology that one day Nasa hope to send to the underwater caves of Europa, one of the moons of Jupiter.”

Living with her husband of three years Robert McCellen, Jill admits that he gets worried when she goes off on another adventure.

“We have an agreement,” explains Jill.

“I call him the minute I surface. That keeps his worry under wraps.”

A bust of Julius Caesar found in a trove of Roman artefacts by divers in the River Rhone is the oldest ever discovered, French ministers say.

The life-sized bust showing the Roman ruler with wrinkles and hollows in his face is tentatively dated to 46 BC - just two years before Caesar was assassinated.

Divers, trained in archaeology, uncovered the imperial bust and a collection of other finds in the Rhone near the town of Arles, formally turned into a Roman military colony by Caesar.

“This marble bust of the founder of the Roman city of Arles constitutes the most ancient representation known today of Caesar,” the culture ministry said, adding that it “undoubtedly” dates to the creation of Arles in 46 BC.

Among other items in the treasure trove of ancient objects is a 5ft 11in marble statue of Neptune, dated to about 210 AD.

Two smaller statues were also found, both in bronze and measuring 27.5in. One shows a satyr – a man with goats’ legs considered a symbol of licentious pleasure - with his hands tied behind his back and “doubtless” originates in Hellenic Greece, the culture ministry said.

Of the discoveries “some are unique in Europe”, Culture Minister Christine Albanel said.

Experts are now trying to understand why the treasures were thrown into the river.

The site “has barely been skimmed,” said Michel L’Hour, chief of France’s Department of Subaquatic Archaeological Research, whose divers made the discovery between September and October last year.

A new search operation will begin this summer, he added.

He said the Arles region of Provence, a hotbed of Roman activities, was “propitious” for discoveries.

A historian’s report that the wreckage of an Air Force jet lost at sea 54 years ago has been found off the Southern California coast brought a surge of emotions for Thomas Theiler, 77, a retired executive and former Air Force pilot.

Theiler’s older brother, Richard Martin Theiler, was in the front seat of a Lockheed-Martin T-33A that went missing just after take-off from the Los Angeles International Airport on Oct. 15, 1955.

Aviation archeologist G. Pat Macha said Tuesday that he and a group of volunteers found Theiler’s plane underneath 100 feet of water earlier this month.

When Theiler, of Savannah, Ga., was informed, he was shocked to find himself grieving for his brother all over again, 54 years later.

“He was five years older than me, a good athlete and everyone loved him, so there was a lot of hero worship involved,” said Thomas Theiler, who followed his older brother into the Air Force. “He probably got his wings two years before I did. We were buddies.”

Macha, 63, is an amateur historian who collects documents about military plane crashes. He is heading up a search for another historic wreck in Santa Monica Bay, a plane flown by a female World War II pilot who disappeared in 1944.

In April, a sonar survey turned up another missing aircraft, and Macha said he identified it by matching Air Force records to the serial number on a piece of the wreckage that the salt water had spared.

The Joint Prisoner of War/Missing in Action Command says it appears likely Macha’s finding on the Air Force jet lost at sea 54 years ago are correct, but Lt. Col. Wayne Perry says the command plans to investigate further and determine whether the water is shallow enough to recover the wreckage.

Thomas Theiler said his brother had a wife and a 6-month-old son. Both died years ago.

The younger Theiler also lost a close friend from flight school that day, Lt. Paul Dale Smith, who was in the cockpit. Smith and the elder Theiler were training to fly with the Aerospace Defense Command and practicing navigation and night flying.

Los Angeles County sheriff’s Lt. Jack Ewell said his department notified Theiler.

“It’s particularly shocking because it’s so long ago. It’s not like people are just sitting and waiting for news,” Ewell said.

Divers are examining the site, but there’s only a remote chance that they’ll find personal effects, remains or any clue about why the plane went down, he said.

The plane had just departed in bad weather bound for its base in Yuma, Ariz., but the pilots didn’t make contact after they cleared the clouds.

At his base in Minneapolis, Theiler got word that his brother and friend were missing and a commander gave him a plane to fly to Yuma and wait for news.

“A pickup drove up with a wheel that a lifeguard found. It was from a military aircraft and they don’t just float up onto the beach. So we knew what happened,” Theiler said.

Macha said Theiler and his daughter got emotional when he spoke with them on the phone.

Theresa Morton, of Lake Forest, Ill., the dead pilot’s niece, grew up imagining her uncle living on a desert island with his friend Smith.

She said she was grateful to Macha for helping write a closing chapter to her family history.

“This news has rocked our world, but on the other hand, it’s really neat,” she said. “I’ve been pulling out all the family photos, my dad’s fighter wings, to show to my kids. It makes for wonderful family time.”