By Markus Ehmann
Have you ever thought about diving a closed-circuit rebreather (CCR)? While there are many different options on the market to choose from, you may have wondered exactly why you should make the move from your open circuit gear to more advanced technology.
Regardless of the different models, here are the five top advantages of rebreathers and how they can enhance your diving experience:
1. More comfortable to dive
Rebreathers are more complex and challenging than open circuit diving, but they also have some benefits to increase your comfort level.
I started diving in cold water and quickly upgraded to a drysuit to enjoy longer and deeper dives. However, one thing I only noticed once I switched to a rebreather is, how much warmth is actually lost through breathing and how much compressed, dry gas increases your thirst.
When diving open circuit, the inhaled gas is decompressed and cools down (Joule-Thomson effect) and has to be dry in order to not cause any free-flowing regulator due to freezing. Our lungs have to warm up the gas, more or less to our core temperature. A rebreather does not exchange gas with every breath and in addition, the chemical reaction in the scrubber heats up the gas with every cycle and reduces the heat loss of your body in cold water even further. In addition, the gas in the loop stays humid and reduces dehydration.
As a rebreather diver, you need to carry enough bailout tanks to handle an emergency and safely bring you back to the surface. On a usual dive, however, these tanks are with you and ready but do not have to be used. This means you can enjoy even deeper Trimix dives without the hassle of switching back and forth between different tanks during the travel and decompression phase. This means less time spent on handling your equipment, reduced risk of switching to the wrong gas, and more time to focus and enjoy the dive.
2. Extended dive time
A rebreather allows you to mix gas on the fly and adjust the share of oxygen you breathe. Just like Nitrox, this makes it perfect to extend the bottom time in the recreational range. But where Nitrox only has this benefit at the maximum operating depth of the dive, the CCR can adjust and extend the no-stop time for any given depth on a multi-level dive. Even if you dive into mandatory decompression stops, they will be significantly less.
This is just like having different Nitrox-gases for every phase of the dive but without the need to prepare and carry so many tanks with you.
Beyond recreational depths, open circuit and CCR has the same decompression profile, as the number of tanks and different gases goes up inevitably. In that area, the rebreather provides another advantage of longer total dive time, providing a useful safety net in an emergency.
If you have ever seen the needle of your pressure gauge move on open circuit while breathing at 90 m /300 ft, you can imagine how this can raise the stress-level when you face an issue.
On a rebreather, the maximum dive time depends on your scrubber duration, which is usually good for a couple of hours. That means that even on a deep Trimix dive or far into a cave system, time to solve a problem does not drain your gas supply. Only the consumed oxygen will be replaced. Any other tanks stay untouched. This gives you time to breathe, think, and act, and honestly, it is very comforting in such a situation. You may need to add additional decompression time on the way out and up, but additional scrubber time is usually more readily planned for than additional tanks on open circuit.
3. Optimal gas
As mentioned above, a rebreather allows you to set the ideal mix for every depth of the dive. This does not only apply to the bottom portion, but also to the ascent and decompression phase.
While ascending, the partial pressure of oxygen remains constant and reduces the partial pressure of the inert gases, usually Nitrogen and Helium. This allows for a constantly high oxygen content to optimize decompression, to reduce time for mandatory stops, and eliminate spikes of inert gases that could cause Isobaric Counter Diffusion (IBCD). This advantage diminishes only for deeper dives, where an open circuit diver must carry many additional gases in even more tanks.
The gas in a CCR is also ‘ideal’ for your budget. Re-breathing the gas and only adding the consumed oxygen means a fraction of the cost. The following dive profile shows a bottom time of 27 minutes to 70 m / 230 ft. A typical consumption for this dive may be around 300 l / 10 cu ft of diluent gas and 230 l / 8 cu ft of oxygen. That is less than a tenth of Trimix gas in comparison to the same dive on open circuit. With the Helium prices on the rise that can be a true cost saver!
4. Silence and aquatic wildlife
A rebreather enables you to dive in total silence and enjoy the environment without any disturbing sound from exhaled bubbles. The absence of unnatural noises allows you to fully immerse into the aquatic world and better enjoy any wreck, cave, drop-off or reef. How much closer can it get to “The Silent World” as Jacques Cousteau imagined?
Also, fish and other animals will no longer be shied away by the bubbles and tend to come closer and stick around. The majority of fish will only stay close enough if their curiosity is greater than their fear of anything unfamiliar. They don’t need bubbles.
Needless to say, this makes it easier to take pictures and videos. Many professional photographers and videographers choose a rebreather as a tool to get the job done for this very reason.
5. Easier logistics
Gas fills and supply hold much longer. Once your bailout tanks are set, you can keep them until you need them in an emergency and there is no need to fill them between dives, if unused. That means the fills your smaller onboard gas tanks are all you need to take care of, even when diving for a couple of days in a row.
Mixing the right gas is down to one diluent tank and not a twin set or a couple of stages, making it much less time consuming and convenient to have the proper result for your next dive. Also, in locations where it is not possible to refill, all you need for additional dives may be another set of 19 or 30 cu ft bottles. That’s easy to manage in comparison to breaking fresh and fully filled 80 cu ft tanks for every new dive.
Lastly, the limits of your CCR setup define the maximum for your dives but are very flexible to accommodate profiles that are less demanding.
Conditions change and you have to switch to a shallower dive site? Your buddy’s gas supply only lasts for a shorter dive-plan? No problem. As long as you stay within your scrubber duration and bailout, your diluent is set for the maximum operation depth and you can flexibly adjust your plan with the same equipment configuration. On top, you do not even waste precious Helium fills.
Usually, rebreather diving comes into play when open circuit diving reaches its logistical limits. However, it offers much more than just advanced diving. Just like open circuit offers a new level of underwater experience when compared to snorkeling, a CCR is another step towards a fully immersive experience. Enjoy the silence and new limits for exploring the underwater world!
To find out more about International Training, visit www.tdisdi.com.
Save £500 on Maldives liveaboard – but hurry, there’s only 2 spots left!
Join The Scuba Place on board the award-winning (Best Liveaboard, Maldives Tourism Awards for 2 consecutive years) Sachika for a week in the sun!
Taking in the very best dive sites of the ‘Best of Central Atolls’ itinerary, including manta cleaning stations, Whaleshark Alley, the Fish Factory and the legendary night dive with hundreds of nurse sharks, this is one trip not to be missed.
To make it even better, they have taken a big chunk of cash off the price to fill the last TWO SPACES (twin or double cabin) on each of the following sailings:
- Outbound 5 November, return 13 November
- Outbound 12 November, return 20 November
The Scuba Place team can arrange flights from any major UK airport, and the whole package will be ATOL Protected. Price includes flights, taxes, full board in a twin/double cabin based on 2 sharing, 17 dives with Nitrox included, all soft drinks and meals and snacks. Bar bill is extra and extra dives are available too!
The prices are based on flying with Emirates and include 30kgs of baggage per person.
Don’t miss out – get in touch today! Call 020 3515 9955 to find out more!
Brochure link: https://bit.ly/TSP_Maldives_Nov2021
Boat images by Top Class Cruising
Underwater images by Nigel Wade for The Scuba Place
The Scuba Genies head to Bonaire! Part 1 of 2
In the first of this two-part blog, The Scuba Genies share their trip report from the Come Dive with Us hosted trip to Bonaire in September 2021…
Travelling during the Covid pandemic has been challenging for some, impossible for most, and missed by all. We have been scanning the rules and regulations daily, and as soon as the UK Government allowed us, we were off!
What was supposed to be a trip to Mexico for a gang of 12 of us, just like most trips over the last 18 months, we were forced to change as the travel rules changed – we have been trying to get to Bonaire for ages, and this became the perfect opportunity – at last!
With our bags packed, negative test results and completed Bonaire health forms in hand – we made an early start for Heathrow, prepared for an 0630 departure. A quick flight and we landed in Amsterdam. As a Dutch Caribbean territory, all flights from the UK to Bonaire on KLM go via Amsterdam. In the airport, we met up with the rest of the gang who had travelled from Birmingham. After a quick layover we took off for Bonaire, where we arrived about 9 hours later. Our health documents were checked at the airport, and we grabbed our bags. It seems odd to have to fly East to then go West, but as we stepped out of the minibus at Buddy Dive Resort, only 10 minutes after leaving the airport, the sunshine and blue sky told us it was worth it!
Our accommodation for the group was made up of two 3-bedroom apartments, a stone’s throw from the water, dive shop, dock and Blennies, the main restaurant and bar. Buddy Dive also has 1- and 2-bedroom apartments along with studios, all comfortably furnished with either a garden or ocean view.
Each 3-bedroom apartment is spread over two floors – but a floor up from ground level. The ‘ground’ floor of each apartment offers a double bedroom (beds can be configured as twins or double in all rooms), a bathroom, lounge with balcony, and a very well-equipped kitchenette. Microwave, toaster, hob, fridge/freezer with ice-maker and enough pots, pans and utensils to satisfy the avid cook! On the upper floor, there are two further double rooms with ensuite bathrooms, both with balconies of their own. Each bedroom is air-conditioned, and the lounge and kitchen have celling fans. All in all, quite perfect for a home away from home for a fortnight!
The rules of group travel say we must unpack (empty bags onto floor or bed), sort kit out (look at dive bag and save it for later), put cameras together (er….NO!) and hit the bar – so being rule-abiding people that we are, this is what we did. Picking up the rental van for our stay would have to wait!
The next morning after breakfast, served in the Ingridients restaurant and right on the water, we attended the Buddy Dive orientation. The staff gave us a quick tour of the dock and resort including the famous drive thru tank shed offering both air and nitrox tanks ready and waiting to be loaded into your vehicle. Check in at the dive centre was easy… we all completed our diver forms online before arrival so with a quick hello we were handed locker keys for our kit storage. Time to head back to the room and get ready for our first dive!! That is why we’re here after all!
As with all trips, the first dive was a check dive, so we climbed down the steps into the water off the dock to go an explore Buddy Dive Reef. Finning over the sandy bottom, past the coral restoration project ‘trees’ and following well laid lines with directional markers we hit the reef after just a minute or two where you can drop to 35+ metres over simply stunning corals. This reef, just like the rest of the sites we dived, is super-healthy and teeming with juvenile fish wherever you look. Moray eels, turtles, octopi and HUGE tarpon on our first dive! What a great start!
The following day we decided it was time to explore the island. We picked up our 6-person minibus from Reception, pulled up to the drive thru tank station and grabbed 12 well filled Nitrox 12l aluminium (A-Clamp – not DIN) cylinders. With our guidebook in hand, off we went driving on the right of course, in search of marine life.
There are over 50 dive sites scattered around the coast of the main island, and even more on the island of Klein Bonaire accessible by boat. We chose a comfortable start by picking dive sites to the South where the entry seems to be a little easier on old knees and hips. We packed up sandwiches we made after a quick shop at the supermarket the day before, along with waters and a few essentials – towels, sunnies and bug spray.
I won’t bore you with every dive site name and description – the guidebook is the tool for that – but it is more than safe to say that we dived, dived and dived again! Every dive gave us far more than we expected, and the marine park surrounding the whole island delivered the goods without fail. Super healthy corals, plentiful marine life, warm and very clear water at 30 degrees made life easy. Parking the van up at the marked dive sites wasn’t difficult, and a few strides across the sand was far simpler than we had expected.
I will say that some sites are a little more challenging to get into the water from – anything more than three or four steps doesn’t float my boat! We adapted our entries for the group – some kitting up in the water, some not, but the rule of thumb quickly became step in up to thigh-depth, inflate bcd, fall flat on your back and paddle out before putting your fins on. Simple! Getting out of the water was pretty much the reverse of the above – stand up when you can, remove fins, and then navigate the rocks and sand channels before you walk up the beach. Nothing that an over-weight, under-tall chap in his mid-50’s with dodgy knees and even dodgier hips couldn’t cope with! (That is me by the way…..no offense to anyone else intended and no animals were harmed in the writing of this either).
We saw stuff – lots of it! Huge tarpon, French and Grey Angelfish, forests of Christmas Tree worms, anemones with Peterson, sexy and cleaner shrimp, clinging crabs, nudibranchs – especially lettuce-leaf slugs, coral-banded shrimp, lobster and so much more. Turtles everywhere, trumpet-fish in unbelievable numbers, and that was generally the story – all in very good visibility too! The corals and huge sponges were stunning with fascinating reef-structures offering all sorts of hidey-holes for critters!
There were some really special sited that we loved, and Salt Pier was one. The Cargill solar salt facility is easily found with its distinctive line of white salt pyramids.Each pyramid, roughly 50-feet high, can contain up to 10,000 metric tons of 99.6 percent pure salt. Even more noteworthy, in addition to the acres of salt ponds, the facility is also home to largest pink flamingo sanctuary in North America. Our very own Chloe has written an in-depth blog about Bonaire and its pure salt so be sure and check it out!
Back to the diving! We were given a hint to drive just past the pier to park where we would find an easy sand entry to the site. We kitted up and finned out through the shallows where we encountered three juvenile hawksbill turtles along with a few smooth pufferfish fighting to feed on patch of sponges, and then made our way under the immense structure of the pier. There are several platforms supporting the conveyor belts that move salt to the container ships and there wasn’t much diver-traffic to contend with. We were amazed by all things weird and wonderful – big scorpion fish hiding under the metal work, angelfish battling for food, schooling fish up above you, and frogfish! Barracuda, Caribbean reef squid, spotted drums, octopus, oh! and more frogfish! Even a flying gurnard in the shallows! What a dive! And as it is shallow, it can be a very long dive too, especially with the 200-210 bar fills the drive-thru often gave us.
Check back for Part Two of this Blog tomorrow!
Find out more about the worldwide dive itineraries that The Scuba Place offers at www.thescubaplace.co.uk.
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Egypt | Simply the Best Itinerary | 04 – 11 November 2021 | Emperor Echo
Jump on board the latest addition to the Emperor fleet and enjoy diving the famous sites of the Red Sea with this fantastic special offer. Great value for money and perfect for small groups of buddies with a ‘Book 5 and 1 dives for FREE’ offer all year round.
Price NOW from just £1275 per person based on sharing a twin cabin/room including:
- Flights from Gatwick to Hurghada with 23kgs baggage
- 7 nights in shared cabin
- 3 meals a day, soft drinks, red wine with dinner
- 6 days’ diving, guide, 12ltr tank & weights, Marine Park fees and port departure fees
- Free Nitrox
Subject to availability.
Alternative departure airports available at supplement.
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