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20 S E P T E M B E R 2 0 1 5 | S P O R T D I V E R . C O M S E P T E M B E R 2 0 1 5 | S P O R T D I V E R . C O M 21

READY FOR A REBREATHER? What you need to know before signing up for recreational rebreather training

B Y TA N YA G . B U R N E T T

If you associate rebreathers only with technical diving, it’s time to take a look at the new Type R, or recreational, rebreathers, such as the Hollis Explorer Sport (shown in the photo at right). These units are lightweight, easy to transport and have sophisticated yet simple elec-tronics, plus they let you experience things you never imagined possible.

“Imagine having an all-access back-stage pass to all the hot Hollywood parties where all the stars know you and love you,” says James Weber, a Semi-Closed Circuit Rebreather and Fully Closed Circuit Rebreather instructor with PADI Five Star Force-E Scuba, Riviera Beach, Florida. “Diving a rebreather

is the same thing — you’ve got an unrestricted pass to get up close and per-sonal with all kinds of ocean life. With no bubbles or sounds to disturb them, you are accepted as one of them.”

1 Do a Training and Skills Check

PADI requires that students have both Open Water Diver and Enriched Air Diver certifications, a minimum of 25 logged dives and be at least 18 years old. Weber says having a good understanding of the basic principles of gas-exchange physics, such as PPO2 (partial pressure of oxygen) and FO2 (fraction of oxygen), and excellent buoyancy skills will make the learning process a bit easier.

3Demonstrate Discipline

To dive these units safely, careful prep and post-dive care is required for each and every dive. “Although recre-ational rebreather diving has come of age, there are still crucial things to remem-ber,” says Weber. “The most important is being disciplined. It’s not the same as just throwing together a tank, BC and reg and hopping in the water.” Before and after each dive, you’ll get your tank filled with an analyzed nitrox mixture, insert the pre-pack scrubber canister, assemble the unit, perform all predive checks — such as positive pressure, nega-tive pressure, flow rate, bypass regulator operation, relief valve pressure and leak checks — and clean and disinfect the unit after the dive.

4Figure Out Your Budget

Courses usually cost between $700 and $1,500. The personal dive gear you need includes a mask, fins and snorkel, reel or finger spool, SMB or lift bag,

Scapa Flow in the Orkney Islands — off the windswept northern tip of Scotland — is a wreck-diving mecca thanks to the remains of German World War I battleships and cruisers lying on the seabed.

This year, I dived the wrecks using a Hollis Explorer eSCR rebreather. The final dive of the week really showed the true beauty of the unit.

The SMS Karlsruhe is one of three cruisers in Scapa Flow, and there is plenty to see along its 367-foot length, most notably an intact stern, com-plete with anchor, 5.9-inch deck guns and a dramatic bow. With the deep-est sections in 82 feet of water, and its highest points reaching 45 feet, even single-tank divers have plenty of bottom time, but on the Explorer, I completed 46 minutes on the seafloor before I got near my no-deco limits, and as soon as I ascended to around 55 or 60 feet, my handset displayed that I had another 48 minutes before I needed to surface. That was a total possible no-deco dive time of over 90 minutes — and all on a 5-liter tank of 40 percent nitrox and small scrubber of sofnalime. Plus, breathing warm gas through the loop helped stave off the cold of the 46-degree water, and with massively reduced bubbles, I could get close to any marine life I encountered. — Sport Diver EMEA Editor Mark Evans

Going with the FlowDiving bubble-free with the Hollis Explorer eSCR on the German WWI cruiser Karlsruhe

Hollis Explorer Sport The compact and lightweight Hollis Explorer Sport’s unique design uses a single cylinder of nitrox, ranging from 32 to 40 percent, and the electronics feature a predive diagnostic that runs with just a few prompts to the diver. It’s electronically controlled to automati-cally analyze the gas mixture, and will adjust accordingly to achieve an op-timal balance of PPO2 and dive time. The unit uses a refillable absorbent cartridge, has optional CO2 tracking and offers a maximum dive time of two hours. MSRP: $4,995.95; optional CO2 monitor kit available for $495.95

What’s Your Type?Understanding how a rebreather works can help you choose which one to buy

2Make a Commitment to Learn

You must be ready to understand how a rebreather system works, the physics and physiology associated with this diving, and how to put the unit together, test and clean it. The course spans roughly four days and includes nine dives. Specific training is required for each model. “Each manufacturer builds its units differently,” says Weber, “so each unit is different in terms of assembly, prep, emergency procedures, post-trip prep and maintenance.” You can rent a unit for the course, and Weber says that “once you learn how to dive one rebreather, you can get an additional unit qualification on another unit.”

bail-out tank and regulator, and an exposure suit adequate for the open-water environment. Added costs include the nitrox fills, scrubber material, and the rental or purchase of the rebreather.

5Experience the Rewards

Rebreathers offer extended dive duration, longer no-decompression times, reduced weight, a warmer gas exchange and the ability to get closer to marine life. “I can get up close and per-sonal with most things that live in the sea with my rebreather, where on open circuit I just scare everything away,” says Weber. “I’ve been able to get very close to goliath groupers and ocean sunfish on my rebreather, something just not really possible on open circuit.” Diving sans bubbles inside a wreck lessens the amount of debris that is knocked down from the ceiling. “If you’re the type who can be disciplined enough, a rebreather can open doors to encounters that you can only dream of,” Weber says.

The advantages of diving on a rebreather are many: longer bottom times, fewer bubbles to scare your favorite marine life, and warm, moist breathing gas. What are you waiting for?

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There are three primary categories of rebreathers: Oxygen, Semi-Closed Circuit (SCR) and Fully Closed Circuit Rebreathers (CCR). These systems vary in the manner in which gas is added or replenished, but all rebreathers must scrub out the carbon dioxide from the breathing gas.