Often jokingly called “crossing over to the dark side,” there’s nothing truly sinister or threatening about training and certifying to dive a rebreather if done correctly. In fact, closed-circuit rebreathers (CCR) are advantageous for many types of divers and diving. And they’re not as complex as you may think. While technical divers have long understood the benefits of rebreathers, here we’ll look at the benefits of rebreather diving for recreational divers.
Longer dive times
Rebreathers allow for longer dive times, as you recycle the exhaled gas in your breath. So, regardless of your depth and air consumption, air supply is no longer a significantly limiting factor. Also, most CCR models supply you with a constant partial pressure of oxygen known as a set point. This can vary from 1.1 to 1.4 PO2, which also extends your no-decompression limit significantly. Think of a rebreather as a wearable enriched air/nitrox-mixing unit; it will deliver the best nitrox mix for any given depth so you can maximize your NDL. In colder waters, you’ll also stay more hydrated and warmer longer on a rebreather, since you don’t lose as much body heat or moisture on each exhaled breath as with open-circuit scuba diving. Rebreather divers commonly spend up two to three hours in the water per dive.
More intimate aquatic encounters
Rebreather divers create far fewer (if any) bubbles and almost no noise underwater. This means it’s much easier to get close to aquatic wildlife. Once you’ve dived a rebreather for a while, you’ll be amazed at how intrusive open-circuit scuba diving can be to aquatic life.
On recent trips to the Galapagos, not only have we enjoyed extended dive times, but we’ve also had much more intimate encounters with sea lions, turtles, hammerhead sharks, Galapagos sharks, schooling fish and whale sharks. We stayed nearly stationary for 60 minutes and saw the natural habitat return by remaining silent for so long. This is one of the reasons many award-winning photographers, videographers and underwater filmmakers use rebreathers.
Who should consider rebreather diving?
Rebreather diving is beneficial for all divers, particularly for underwater photographers or videographers. Divers who want to stay underwater longer, on deeper sites or wrecks that are still within recreational depth limits benefit from rebreathers as well. A rebreather offers the advantage of a nitrox NDL, yet with an extended air supply. Even on shallower dives, a rebreather could you to remain underwater for three hours. For divers who needn’t follow a boat schedule, the extra time underwater makes the additional set up and pre-dive check time necessary for a rebreather worthwhile.
Why isn’t rebreather diving more popular?
If rebreathers are so great, why doesn’t everyone dive with them? One of the main obstacles to entry is the initial cost and investment in training and owning a unit. A new recreational rebreather ranges from $5,000 to $8,000, so a significant financial commitment is necessary. In comparing this to what a recreational diver would spend for a new open-circuit regulator, tanks, BCD and dive computer, the price difference does dissipate a bit and give some justification to the committed diver.
Many divers also think of rebreathers as too complex and riskier than open-circuit diving. Although engineers have designed some modern rebreathers to be more user-friendly, this type of diving does require a more disciplined diver to stay safe. If you’re the type of diver who loves to just chuck their gear on, hit the water and Zen out on a dive, it’s probably best to stick with open-circuit scuba. Good rebreather divers, by nature, are disciplined, meticulous, patient, and attentive — with a slight degree of paranoia.
When, how and what type of unit should I buy?
With many different units available, choosing a rebreather can be like choosing a new car that best suits your needs. Technical divers may opt for a more complex unit, designed for specifically for depth and extended decompression. Recreational rebreather divers should choose a user-friendly unit that’s easy to abort from a dive if needed. Main manufacturers of recreational rebreathers include Ambient Pressure, Poseidon and Hollis, though the Explorer is technically a semi-closed rebreather. Although some agencies allow complete beginners to learn to dive on a rebreather with a basic entry level/open-water certification, it’s far better that a diver should have a good level of comfort in the water. Divers must be able to handle stress underwater and possess good situational awareness before considering rebreather diving.
A rebreather can throw curve balls at you during a dive, so you must be able to handle yourself and the environment before taking on the added task of a managing a rebreather underwater. Most training agencies, such as PADI, SDI and SSI, offer recreational rebreather entry-level courses of three to four days long. These come with the basic prerequisite of holding an open-water or advanced open-water certification and enriched-air certification. Training on a rebreather is unit specific, though crossover programs are possible. Certification on one type of rebreather unit does not automatically qualify you to dive other types of rebreathers due to the unique nature of each manufacturer’s unit.
What’s next after certification?
After a period of inactivity with recreational open-circuit diving, a refresher course is like learning to ride a bike again. Usually motor skills and knowledge return easily and rapidly. However, rebreather diving mistakes can be far less forgiving than open-circuit scuba, even fatal. There’s a different mindset when diving a rebreather as opposed to traditional scuba. This makes it even more important to dive frequently. When necessary, rebreather divers should not hesitate to take a refresher course under professional supervision. Rebreather technology is evolving faster than traditional open-circuit scuba, so it’s equally important to stay up to date with agency training standards, changes in technology and manufacturer’s guidelines and recommendations.
If you’re still not sure about rebreather diving yet, check out this short video clip from a recent Galapagos trip. Convinced yet?
Interested? Learn more about becoming certified to dive on a rebreather here.