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RTC Launches New Rebreather Safety Initiative



Header image: Rebreather diver wearing their MRS. Photo courtesy of rEVO.

In January 2021, the Rebreather Training Council (RTC) began developing several new safety initiatives in addition to its ongoing work on the advancement and development of rebreather training standards. RTC launched the first of these rebreather safety initiatives in March in an effort to reduce rebreather fatalities. 

Specifically, the initiative has been designed to educate and inform divers about the advantages of using mouthpiece retaining straps (MRS). The RTC now recommends the use of an MRS when diving a rebreather. It further recommends that rebreather divers be taught about the advantages of an MRS during their training, and that vendors supply them with their rebreathers (as is required according to the European rebreather standard EN14143). 

It is widely acknowledged that the use of rebreathers increases the probability of exposure to an inappropriate breathing gas, which can lead to a Loss of Consciousness (LoC). As sport rebreather diving community leaders, the RTC and its members believe the specific risk of water aspiration following LoC underwater must be proactively mitigated. An MRS is an easy-to-use, easy-to-fit device that prevents the mouthpiece from being lost in the event of (LoC), and can therefore minimize the risk of immediate drowning.

A mouthpiece retaining strap (MRS). Photo courtesy of AP Diving

According to Mark Caney, President of the RTC, “There is good evidence that Mouthpiece Retaining Straps have meaningful safety benefits, so we hope that all rebreather divers will take time to learn how these simple devices are deployed and embrace their use whenever practical.” He was joined by RTC vice chair Paul Toomer, “I have been using an MRS on my rebreather for some time now and I’m really happy to see such a great safety initiative being released into the mainstream,” he said.

The RTC’s desire is that all divers, instructors, and manufacturers will embrace this initiative as we continue to strive to make our sport ever safer. For a detailed explanation of the use and safety advantages of MRS, see MOUTHPIECE RETAINING STRAP SAFETY GUIDANCE NOTICE posted on the RTC website.

Additional Resources:

BSAC Webinar: Increasing The probability of Surviving Loss of Consciousness Underwater When Using A rebreather

InDepth: Can Mouthpiece Retaining Straps Improve Rebreather Diving Safety?
Where do Agencies and Manufactures Stand on Mouthpiece Restraining Straps?

A Mouthpiece Restraining Strap Just Might Save Your Life
—We surveyed CCR divers from around the world on MRS: Here are the results.


It’s Your Call




by Sheck Exley, October, 1992.

Header image: Seventeen year-old Sheck Exley displays his newly set depth record at Zuber Sink [later renamed Forty Fathom Grotto], just before his 18th birthday. Photo courtesy of Mary Ellen Eckhoff and Brian Udoff.

Since I retired from the car business seven years ago, I’ve had a blast teaching algebra and calculus to high school kids in Suwannee County, Florida. Most of the kids have no idea that I am a diver, but a few find out and inevitably ask me to teach them to dive or sponsor a scuba club. I will never do either for fear of encouraging the “macho” so evident in teen-aged males. 

The guy that taught me how to dive, Ken Brock, had more guts than I have. In early 1966, he organized a scuba club especially for teenagers called the “Aquacks” at the Jacksonville YMCA and promptly ordered us to “stay out of caves”. Given the poor technology available to cave divers at the time, abstention was the only rational advice to give to the aspiring diver.

Ken Brock taught Sheck how to dive. Photo courtesy of Mary Ellen Eckhoff & Brian Udoff.

So what did we do?  You guessed it!  While cave diving at Jugg Hole on April 3, I got caught in a current, hit my head on a rock and flooded my mask.  On July 16, at Orange Grove Sink , my partner and I got narked and entangled in our line. Later the same day, I discarded the troublesome line, got lost at Peacock and exited the cave by an unknown route with only a couple of minutes of air left. The next weekend I got lost in a silt out at Ginnie Springs and dug my way out through a restriction on my reserve air supply. Later the same day, my partner ran out of air and attacked me. He survived only because Ken had taught me how to do CPR.

This experience should have stemmed my obvious problems with testosterone excess. Instead, I was portrayed as a “hero” for saving my partner’s life, and became more arrogant than ever. My youthful partners and I—including Joe Prosser, past training chairman of the NSS Cave Diving Section—continued to scare the heck out of Ken with our illicit cave diving escapades and close calls, diving ever deeper in a never ending quest to impress each other and prove how “brave” we were.  By August, 1967, I had hit 237 feet at Zuber Sink, now “Forty Fathom Grotto,” the club record. 

I was the clear leader of the club, as well as its hero. My greatest admirer and emulator was probably my brother, Edward, who was three years younger than me. He bought equipment that looked like mine, gave talks about me in school, and even copied my mannerisms. It was great to be held in such esteem by him and the others.

On June 29, 1968, we stopped at Wakulla Springs for some snorkeling on our way to Morrison Springs, where I planned to try to set a new club depth record. I got cold and got out, but Edward, ever eager to impress me, said he wanted to stay in a little longer. I told him to be careful, then watched him swim out to the deepest section, take a few breaths, and disappear behind the huge ledge. A minute later he reappeared, swimming at a strange angle instead of straight up to the surface. When he got to the surface he kept on swimming instead of clearing his snorkel, then slowly started sinking toward the 125 foot bottom. After an hour of CPR, my mouth filled with his vomit, we had his heart and lungs going again, but he never regained consciousness.  My only brother, Edward, was dead. I was the one who had to make the call to my parents. 

Virtually all human progress since the dawn of time has come from that desire to achieve, excel, and discover; but this desire should never be used as a rationale for cutting corners on safety procedures or leading unqualified partners into danger.”

Left to right: Unknown friend, Sheck Exley, Edward Exley at Cowpen Lake, c. 1967 or 1968. Photo courtesy of Mary Ellen Eckhoff and Brian Udoff..

If machismo stopped upon reaching the age of 20, we could prevent most diving accidents by simply outlawing diving at a younger age. Unfortunately, many of us seem to remain adolescents indefinitely. Don’t get me wrong. I applaud record setting in diving; virtually all human progress since the dawn of time has come from that desire to achieve, excel, and discover. I also recognize that much of this motivation comes from the desire for recognition and esteem, a trait shared by all of us. But this desire should never be used as a rationale for cutting corners on safety procedures or leading unqualified partners into danger. Unless, of course, you want to make a phone call like I did.

Postscript: Exley died two years after writing this story at age 45 while trying to bottom out the world’s deepest sinkhole, Sistema Zacatón in southeastern Mexico, which is estimated to be 339 m/1,112 ft deep.

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