Today Mark Slinn (intern) and Andy Cavell (intern) completed their TDI O2 Service Technician Course. This would be the most recent service and technician related course after completing their TDI Visual Inspections course last week.

The o2 Service Technician builds on servicing regulators and cylinders but to a “oxygen clean” level. The students began by stripping and cleaning an Scubapro Mk2 1st stage and R295 Second stage and cleaning it removing any source of hydrocarbons. After a full clean and inspection the regulators we re assembled and tested. After full assembly the regulators were marked and recorded to be used in future training when breathing oxygen underwater. You can read more about this unique course here.

As the internship progresses the interns will be required to attain the SDI Divemaster certification and later the TDI Technical Divemaster certification. Since they are already PADI Divemasters all they had to do was cross over their skills and fill the gaps in the training.

One of these gaps is the most unpleasant swim tests and “surface recovery” or “ditch and don” exercise. The swim test are similar to other organizations with slight differences and the ditch and don exercise is rarely in a divemaster program in any official capacity (although many introduce it). At lunch we hit the water to cover these skills and stamina tests. The ditch and don is described as sinking your scuba gear, freediving down to it and assembling it underwater in about 3m. There are more steps to it but that’s the general description.

All of them did really well except Mark. Mark is a former soldier from the Parachute Regiment and is considered rather tough, however a cold got in his way and he couldn’t get down. He spent the remainder of the day blowing his nose and generally moaning on the surface with the instructor. He’ll get another chance in a few days.

In the afternoon the students cleaned their lean decompression mix cylinder while Ash cleaned twin set in preparation for our epic diving adventure in January. Once the practical work was finished the students sat a written exam and put all the tools away to prepare for the TDI Compressor Operator Course (distinctive) tomorrow.

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

For the past 14 years, photographer and filmmaker Jill Heinerth has been exploring underwater caves around the world, from lava tubes off the coast of North Africa to icebergs in the Antarctic. Wired.com recently caught up with Heinerth to talk about some of her most exciting cave diving moments, as well as the recent technological advances that have made cave diving easier, safer and more accessible to recreational divers. This gallery showcases some of Heinerth’s best underwater images and includes captions adapted from our conversation with her.

Above: “My Neighborhood Cave” in High Springs, Florida

Heinerth snapped this photo of herself as she descended through the tannic water of the Santa Fe River into her neighborhood cave in High Springs, Florida. The swirling orange blaze above her comes from the mixing of river water, stained red by decaying cypress trees, with crystal blue spring water flowing from the cave. The giant black mask she’s wearing is connected to a special diving tank called a rebreather.

“Basically, it does the same thing as a space suit,” Heinerth said. “In normal scuba gear, you’re inhaling gas and exhaling a column of bubbles into the water. But in a rebreather, you’re actually recycling your air, with carbon dioxide getting scrubbed out of the mixture and oxygen getting added back in. With an electronic rebreather, you can tune the gases that you’re using, so that in deeper water you can use helium and other gases to get the optimal mixture of breathing gas for deep water.”

See more here

Freediving is any of various aquatic activities that share the practice of breath-hold underwater diving. Examples include breathhold spear fishing, freedive photography, apnea competitions and, to a degree, snorkeling. The activity that garners the most public attention is competitive apnea, an extreme sport, in which competitors attempt to attain great depths, times or distances on a single breath without direct assistance of self-contained underwater breathing apparatus (scuba).

Recent interest in this sport has caused dive schools to look at this side of diving as a great alternative to traditional underwater interaction. A recent article in the Times about Freediving in Koh Tao reviewed the sport, the island and the local leaders in free diving; Apnea Total. In the article Guyan Mitra says:

By the end of the two-day course, I was comfortable at 20 metres, a depth that had sounded inconceivable 48 hours earlier. Plus, I was able to dive Ko Tao’s newest underwater site. A boat had recently sunk — without casualty, thankfully — creating a modern wreck around which a kaleidoscope of tropical sea life was investigating.

Using my new-found skills, I was able to probe and glide in and around the wreck, just like my fellow fish. Not quite a merman, but getting there… definitely getting there.

That article in its entirety can be found here

Additional interest was generated from the inflight magazine for Bangkok Airways; “Fah Thai” where photo journalist and fellow technical diving enthusiast Ayesha Cantrell reports about the growing trend of breath hold diving growing on Koh Tao. In the report Ayeasha says:

Go scuba diving around Koh Tao in the Gulf of Thailand and you may encounter a mermaid. Propelled by her monofin to depths of 50 metres on a single breath of air, Monica Ganame is the nearest you’ll get to meeting one of these mythical creatures underwater.

The Argentinian-born professional free diver wears no air tank or other bulky scuba gear - instead, Monica can hold her breath for up to six minutes and explore the underwater world in its truly natural state. The absence of dive equipment not only allows Monica to interact much more closely with marine life, but also to feel a part of the ocean herself.

Ayesha is referring to Monica Ganame who is co-owner of Apnea Total on Koh Tao, that article can be found here

One of Apnea Totals protege’s is Jeroen Marteens who became a freediving instructor through their school. Jeroen is your typical freediving instructor; Tall, slim and appears to be someone who likes his yoga and perhaps a bit of incense. Jeroen join the Big Blue Family to start our Big Blue Freediving department and has been very busy ever since. With maximum 3 people per course.

Jeroen will be taking out members of the Big Blue Tech team for their freediving course later this month, although there were grumblings between wearing 6 cylinders or none at all it is a fringe and extreme side of scuba diving so technical diving and freediving have quite a lot of similarities.

You can find more details about these courses: Freediver Basic and Freediver Advanced

One of the downsides of travelling with your scuba equipment is being charged excess luggage fees by increasingly thrifty airlines, especially if you’re using budget carriers. Here’s some tips to flying with your scuba gear in South East Asia less expensive and less hassle

The budget carriers standard international baggage allowance is 15kg. My dive bag with my full set of scuba gear, a hefty Ikelite camera housing, a couple of books, a few changes of clothes and a washbag of toiletries weighs in at around 26kg. My camera backpack which I carry on can weigh anything up to 12 kg with camera, strobes, laptop and the assorted chargers and cables. I try to pretend the backpack is superlight as I nonchalantly stroll towards the check-in desk, but inside I’m screaming…

Even with the excess charges, it’s still usually much cheaper to fly with one of the budget airlines than one of the traditional carriers who usually offer a 30kg allowance, although you shouldn’t take that as gospel. (Check on Kayak.com for a spread of current fares offered by the big name carriers and Skyscanner for the budget carrier prices - and don’t forget the airline websites themselves).

The other thing to consider is that budget airlines are point-to-point, which means they will not transfer your bags to another flight - you have to retrieve it and go check in again yourself. If you have multiple flights, you probably want to avoid doing this.

The big problem with excess scuba baggage is the sheer hassle of actually checking in. The weighing, form-filling, and paying at another desk is a time-consuming pain, and there’s always some uncertainity about how much you will be expected to pay. Most of the time it comes down to what mood the check-in staff are in. This can make check-in a fairly unpleasant and stressful experience.

However, things are starting to improve if you know where to look and so I thought a rundown of my experiences with various Asian budget carriers and their scuba diving equipment policy might be useful for other budget scuba travellers.

Multi Country Budget Carriers:

AirAsia - the biggest of the budget carriers in Asia and the one you are most likely to encounter. AirAsia have a strict policy of charging for all excess baggage which they zealously enforce. However, this Fee Schedule page on the AirAsia website shows that AirAsia have a sporting goods weight allowance, which they’ve always kept very quiet. The customer pays a fixed excess fee of around $10 US for up to 15kg extra (ie 30kg total weight allowance). On recent AirAsia flights from Bali - Jakarta - Bangkok, I had to check in twice and on showing a print out of this AirAsia webpage was allowed the Sporting Goods Weight Allowance. I don’t think I would have got it without the print out - the staff were all ready to charge me the full excess until I politely showed them the fee schedule.

Jetstar - lets you purchase a Sports Gear allowance at the time of booking. Much more civilised as then there is no hassle at check-in. I have no problem with paying a fixed amount extra to transport my dive gear on a budget carrier. You have to purchase the allowance for each sector or leg of your journey, so for both going out and coming back and any stop-offs inbetween.

Tiger Airways - Tiger also have an enlightened Sports Gear upgrade policy, where you buy an allowance at time of booking. As with Jetstar, you need to buy the allowance for each sector of your journey.

Philippines:
Air Philippines (not to be confused with Philippine Air) - Will wiave any excess baggage charges if you show your dive certification card (e.g. PADI). This is the official AirPhilippines webpage that states the scuba weight allowance.

Cebu Pacific - Cheap prices but a nightmare customer experience. Cebu always charge for the excess and will sometimes ask to weigh your hand luggage as well to ensure it’s not over the prescribed 7kg. They make zero allowance for scuba divers despite scuba diving being a prime driver of Philippines tourism. Cebu Pacific’s domestic charges for excess baggage are fairly minimal, but Bangkok to Manila can be expensive at 200 Baht per kilo over 15 kg. Cebu’s flights are so cheap that even with the excess baggage their prices are still way below any other carrier, hence why I’ve flown with them numerous times, but they could be a lot more efficient and effective.

Thailand:
Nok Air - wiaves any excess baggage charges if you show your dive certification card, but it depends on the staff. In Bangkok the check-in staff volunteered this information, which was a pleasant surprise and a money saver. In Krabi, the staff had never heard of the policy and had to spend several minutes finding a supervisor to approve it. I suggest printing out this page of the Nok Air website which specifically states “Carriage of diving equipment is accepted. Weight of diving equipment is included in normal checked baggage allowance, and is entitled of 20 kg free of charge.”

Indonesia:
I flew domestically with Garuda, LionAir, Merpati and Wings whilst getting to and from Raja Ampat in Papua. We were not charged an excess as far as I know, but we were being checked through as a group by our liveaboard company MSY Seahorse. I don’t know if there were excess charges that the liveaboard guys took care of without telling us (would be expensive for them) or if being a group the airlines simply let it pass. I don’t have any further experience of flying with Indonesian airlines, so if anyone can clarify, that would be great.