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Rebreather 101 with Paul Toomer
How many of you have heard of Jacques Cousteau? All of you, right?
If you don’t know who he is, you need to be on the ‘Horse and Hounds’ or ‘Amateur Rambling in the Cotswolds’ website rather than Scubaverse. He invented SCUBA didn’t he? Didn’t he also write a book called the silent world?
Now, we all know he didn’t invent SCUBA; that was actually some geezer whose name we can’t remember and Mr C just stole all the glory, right?
Wrong! Well… partially wrong. Mr C stole the open circuit glory but not SCUBA. SCUBA is self contained underwater breathing apparatus and it was invented a long, long time ago. And it was a Closed Circuit Rebreather (CCR). That is why his world was SILENT. Open circuit is hardly bloody silent. If you don’t believe me, take a try dive on a rebreather and listen for when the hordes of wildebeest come charging past you blowing those confounded bubbles.
What is a Rebreather?
A rebreather is a closed breathing circuit (loop) enabling gas to be recycled, therefore giving the user an extended use of the limited gas that he/she carries. There are two primary problems that have to be overcome to make the rebreather work though. The first is the fact that we metabolise oxygen, and if we breathe too low an amount of oxygen it can cause unconsciousness, which could of course lead to an ultimately death. A by-product of oxygen metabolism is the creation of carbon dioxide, and this insidious gas can also lead to unfortunate circumstances, especially underwater (as I’m sure you can imagine).
The loop and how it works
When a diver exhales, his breath is forced through a non-return valve which forces the exhaled air through a carbon dioxide removal system known as a scrubber (I love that word). The scrubber is made up of a chemical called Sofnalime, which is primarily calcium hydroxide. The exhaled breath is scrubbed clean of carbon dioxide and the breath is now pushed through an area where oxygen analysers analyse how much oxygen is left in that cleaned breath. The analysers talk to a computer (the unit holds a constant PO2 or oxygen partial pressure) which then tells a solenoid to open and add oxygen to the loop if required. This can also be done manually of course in the event of any problems.
There are also counterlungs on the unit, which allow the diver to breathe gas around the loop. Without the counterlung the diver would be unable to breathe. It’s similar to trying to breath out of a glass bottle; it’s impossible. However, breathing out of a plastic bag is possible, although very unsafe. As the diver descends in the water hydrostatic pressure acts on the counterlung and compresses the gas within it. To enable the diver to breathe, diluent gas (a gas containing one or more inert gasses, normally air or trimix) is manually or automatically added to the loop.
Finally, due to the fact that the CCR holds a constant PO2, compared to open circuit where it’s optimum PO2 is only achieved at the Maximum Operating Depth, rebreathers will penalise the diver less in terms of decompression obligation. Another huge plus.
Gas, Gas, Gas!
Rebreathers work on metabolic rate and not surface air consumption rate. This means that if a diver uses 20 litres of air a minute but only metabolises 1 litre of oxygen, the rebreather is massively more effective at conserving gas. An example of this based on the above gas usage rates would be: An open circuit diver is at 30 metres on the Thistlegorm, for example, and is there for 30 minutes. He uses 20 litres/min x4 ata (30 metres) x30 minutes = 2400 litres of gas, or a full 12 litre cylinder pumped to 200 bar. If a CCR diver was at the same depth and for the same time he would use only 30 litres of oxygen. Therefore, if the CCR diver had a 2 litre cylinder filled to 200 bar, he would have 400 litres available. Based on a 1 litre metabolic rate that diver could stay on the Thistlegorm for 400 minutes or 6.66 hours.
6.66 hours compared to 30 minutes? A gigantic difference I am sure you’ll agree. This is the primary reason that deep technical divers prefer CCR. It’s all in the gas.
Aquatic Life
I took a CCR to the Maldives on a liveaboard a few years ago. I never went past 40 metres for the two weeks I was there and apart from the fact that I never had any decompression schedule, I was swamped by the aquatic life. I was chased by barracuda, nibbled by moray eels, had a 2 metre stingray push me down the reef as if I was not there. Mantas thought I was some kind of weird yellow box fish and finally, the sharks…..oh my God, it was unbelievable! I had white tips on a night dive try and beat me up, chewing my fins and rubbing themselves on me as they went passed, banging into me to see what I was….just incredible. It was one of the best dives of my entire life. This dive alone was enough reason to spend all that money on my unit.
Here is a little history for you:
- 17th century – the first rebreather was conceived by Giovanni Borelli
- 1878 – the first practical system produced by Henry Fleuss, who after diving his fully working unit swore he would never dive in the damnable thing ever again. He absolutely shit himself while doing some work in a flooded tunnel.
- 1881 – the first CO2 absorbent used by Khotinsky and Lake
- Prior to WWI – Dräger started produced rebreather systems. Mainly used for blowing the crap out of poor old Allies.
- WWII – Italian & British Navies used Oxygen & Nitrox systems. The Italian units were mainly used for long swims away from enemy lines back to Italy. The British units were primarily used for blowing the crap out of the Axis countries.
- 1990s – manufacturers launch many units including: Sentinel, Inspiration, Evolution, Megaladon, Ouroboros, Kiss, Optima, rEvo, Poseidon Mk 6, etc.
All that is left to do now is pick your unit, get some top end training and go and play. I assure you this is the future.
Next time we will look at some of the CCRs available, their features, recreational and technical CCR, and of course training options.
Please note that this article covers the basics of CCR. I really hope it gives you a little understanding of rebreathers, as I believe they are the way we will all dive in the future.
Paul is the Director of Training at RAID. To find out more about the courses that RAID offers, visit www.diveraid.com.
Ho Ho Ho! Vobster Quay’s recording-breaking charity Santa diving event returns on Sunday 15th December 2024 for another round of festive fundraising frivolities. Run in aid of the Royal National Lifeboat Institution (RNLI) and Help For Heroes, this ever-popular annual fundraising event aims to raise sack-loads of cash for these two very deserving charities.
Divers of all levels are invited to grab their Santa outfits – and as much festive cheer as they can muster – and head down to Vobster Quay near Mells, Somerset for a mass sponsored Santa dive in aid of charity. In previous years, the event has attracted divers from the far corners of the UK to join in the festive merriment for a final festive dive before the Christmas and New Year break. Back in 2015, the event smashed the world record for the most Santa divers with 188 divers taking to the waters donning their festive finery – a record that remains unbeaten to this day!
Vobster Santas isn’t just about setting records – it’s also about raising some serious cash for charity. Vobster Quay encourages all divers to get into the spirit of the season to raise much-needed funds for two very deserving charities – the Royal National Lifeboat Institution (RNLI) and Help For Heroes.
Through individual sponsorship and online donations, divers can invite their friends, family and work colleagues to sponsor them to plunge into the balmy waters of Vobster Quay dressed in full festive finery. Since the very first Santa dive in 2007, the event has raised over £52,000 for charity. “It’s been over 17 years since the very first charity Santa dive took place at Vobster Quay and every year the event just keeps getting bigger and better” enthused Vobster Quay owner, Amy Stanton.
“Vobster Santas is a great way for divers to say a massive thank you to the both the RNLI and Help For Heroes – two very deserving charities close to our hearts. We’re immensely proud of all that Vobster Santas has achieved and hope that even more divers will join this year’s event on Sunday 15th December. I’m confident that we can make Vobster Santas 2024 the biggest yet!”.
Divers wishing to participate can get involved by simply registering their attendance at
www.vobster.com/event-vobstersantas.php.
Blogs
Dive into Adventure at Hideaway Beach Resort & Spa: The Ultimate Diving Destination in the Maldives
Tucked away in the remote northern Haa Alifu Atoll, Hideaway Beach Resort & Spa is a premier destination for anyone seeking an unforgettable underwater experience. With over 30 dive sites to explore, divers of all levels can witness the unique and mesmerising beauty of the underwater world. Whether you’re a seasoned diver or new to the sport, Hideaway offers an exceptional diving adventure that is not to be missed.
Explore the Beauty Beneath the Surface
Hideaway is perfectly situated near some of the most spectacular dive sites in the Maldives. The dive school and team at Hideaway offer a very personalised experience to ensure each diver gets an interactive, immersive experience.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Unique dive spots such as Theefaridhoo Thila (Heaven and Hell) as one of the 50 best dive sites in the whole of the Maldives, known for its beautiful soft coral gardens.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
As the resort is located next to a channel which gives guests surprise visits from eagle rays, manta rays, guitar sharks and more.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
One of the standout features of diving in the Haa Alifu Atoll is the abundance of rare and exotic marine species. The area is known for sightings of whale sharks, manta rays, turtles, and a variety of colorful reef fish. Diving at Hideaway Beach Resort & Spa offers a rare opportunity to encounter these creatures in their natural habitat, creating lifelong memories for guests.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Whether you’re exploring deep coral gardens, dramatic overhangs, or vibrant reef walls, each dive offers something new and exciting. The visibility in the Maldives is exceptional, often exceeding 30 meters, making it ideal for both underwater photography and general exploration.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Diving for All Levels
At Hideaway, we believe that everyone should have the opportunity to experience the thrill of diving. That’s why we cater to divers of all levels, from beginners to experienced professionals. Our professional dive center, led by expert instructors, offers a range of courses and guided dives. If you’re new to diving, you can start with an introductory course that will teach you the basics of scuba diving in a safe and controlled environment.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
For more experienced divers, we offer advanced dive courses and guided excursions to some of the more challenging dive sites. Our instructors are knowledgeable and passionate about the local marine life, ensuring that every dive is not only safe but also informative and enjoyable.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Exclusive Diving Offer
To make your stay even more unforgettable, Hideaway is offering an exclusive diving package designed to enhance your experience both above and below the water. When you book a minimum 7-night stay, you’ll receive:
- 35% discount on room rates.
- Complimentary diving: 3 dives per person for 2 guests, allowing you to experience the beauty of the Maldives underwater world.
- Free meal plan upgrade: enjoy a complimentary upgrade from Bed & Breakfast to Half Board, or from Half Board to Full Board. Guests who prefer the White Platinum Plan (WPP) can avail it at a discounted rate.
This incredible offer provides the perfect opportunity to experience world-class diving while enjoying all the luxury and comfort that Hideaway Beach Resort & Spa is known for.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Combinable Offers for Even More Value
This diving offer can also be combined with our Anniversary and Honeymoon offers, allowing you to create the perfect celebration package. Whether you’re celebrating a milestone or simply seeking a romantic getaway, this offer ensures that you can enjoy the best of both worlds – luxurious accommodations and unforgettable diving adventures.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Terms & Conditions
- This offer is available exclusively for bookings made through the official Hideaway Beach Resort & Spa website using a specific booking code.
- The offer cannot be combined with other promotions available on the website or through other channels, nor can it be redeemed for cash.
- All dives are subject to weather conditions, ensuring the safety and enjoyment of all guests.
- Black-out dates: This offer is not available from 24th December 2024 to 9th January 2025.
To book this exquisite offer, use the Promo Code: SCUBA24FD
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Hideaway is not just a resort; it’s a sanctuary for those seeking peace, adventure, and luxury. With spacious villas, private pools, and world-class dining options, the resort offers everything you need for a perfect holiday. From tennis, golf, gym, cycling to the exquisite underwater activities, unique dining options, Hideaway has something for everyone. And for diving enthusiasts, it provides an unparalleled opportunity to explore some of the most beautiful dive sites in the world.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
Our dive center is fully equipped with state-of-the-art gear, ensuring that every dive is safe, comfortable, and enjoyable. Our instructors are passionate about the underwater world and are eager to share their knowledge with you, whether it’s your first dive or your 100th.
Email: reservations@hideawaybeachmaldives.com / Call: +960 650-1515 / Website: www.hideawaybeachmaldives.com
The Ultimate Dive Adventure Awaits
If you’re looking for an unforgettable diving holiday in the Maldives, look no further than Hideaway Beach Resort & Spa. With over 30 dive sites, unique marine life, and exclusive offers, we provide the ultimate underwater experience. Whether you’re celebrating a special occasion or simply seeking adventure, our diving package offers exceptional value and incredible memories.
Book now through our official website to take advantage of this exclusive offer and prepare for the dive adventure of a lifetime.
Email: reservations@hideawaybeachmaldives.com
Call: +960 650-1515
Website: www.hideawaybeachmaldives.com
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