That is why gas extenders rule!
News that SDI/TDI instructors can now present KISS GEM programs to interested recreational sport divers opens up a whole world of possibilities for people who want the benefits of a rebreather without the full-on commitment of the classic closed-circuit training and regimen.
A quick survey of the hot topics on the scuba forums among divers will usually turn up at least one newly-minted open-water diver asking how to get his (or her) gas to last longer. “I can burn through aluminum 80 inside of 15 minutes and my (more experienced) buddy always surfaces with half a tank left!”
And we all know the usual advice: gain experience, work on aerobic fitness, streamline your gear, work on buoyancy and trim skills, etc., etc. But no matter how much experience one gains, or how efficiently your body uses oxygen, or how skillfully you glide through the water, there is a limit on how far you can get. The fascination with making your supply of compressed air last a little longer is never satisfied.
The major limitation of course is open-circuit technology. A diver only uses a small percentage of the oxygen in his compressed gas and when he exhales, the remainder is lost with his exhaust bubbles.
Rebreathers recirculate those exhaust bubbles, remove the carbon dioxide, and in some form or another — depending on the type of rebreather — top up with a squirt of new gas so the diver can continue seamlessly with his dive. The technology behind rebreathers is far from new but a few years ago, rebreathers of any type were the almost exclusive purview of military, scientific and technical divers. The sticker price, intensity of the training programs, and the upkeep and protocols required to dive a traditional rebreather purring along presented a turn-off for the majority of divers. Thus, rebreather divers represented a tiny percentage of the whole diving community.
This viewpoint has undergone a radical shift in the last couple of years. Specifically, rebreather companies have revisited the design and function of the traditional rebreather to make it more applicable and more appealing to a much broader market.
One approach is that adopted by KISS (Jetsam Industries) — well known for its innovative closed-circuit rebreathers.
Their KISS GEM is a recreational diving system, standing for Gas Extender Machine, which makes this a semi-closed diving system that allows divers to get around three times the usual dive time on a cubic foot of gas as they would on ordinary open-circuit.
The KISS GEM stands apart from other rebreathers, both semi closed and fully closed, because its design is compact, “bolts onto” a diver’s existing cylinder and is economical.
The GEM gives the benefit of rebreather diving with warm moist air to breath. This alone, in the opinion of many divers, is a huge benefit. SCR and CCR divers explain that at the end of their dive they are less fatigued and do not experience cotton mouth, even on the longest dive.
Photographers on rebreathers like the fact that there is no rush of noisy bubbles to scare the fish away.
All GEM divers will enjoy the benefits of diving enriched air nitrox (initial training on the unit is done with an EAN36 as breathing gas).
Because the GEM is an SCR gas extender, and the “scrubber” (where the carbon dioxide is removed from exhaled gas) uses a pre-made replaceable cartridge that is simply dropped into place rather than loose material that has to be packed very carefully by the diver, GEM operation is only slightly more complex than assembling and operating traditional open-circuit gear, and training programs are aimed at open-water divers with moderate experience.
However, as simple and straightforward as the GEM system is, its appeal is far wider than active sport divers and there are several technical divers — specifically cavers — who have resisted the switch to full closed circuit rebreathers but are using the GEM as a new and exciting way to “do their thing.”
With a growing number of TDI/SDI instructors offering programs on the KISS GEM, it is probably a safe bet to say that you will be seeing one at a dive site near you in the very near future, with a TDI diver attached!
To learn more about TDI training in your area, please visit https://www.sdi-onlinetraining.com/divers/index_facilities_courses.php?site=2 to find a facility by course.
To learn more about TDI courses available visit https://www.tdisdi.com/index.php?did=51&site=2