It is greener than The Big Blue and it is on the Welsh border instead of in the Mediterranean but the team from SaltFree manage to pack in some fun and safe freediving. A video from last month's session shows both graceful freediving and tech-laden support divers in the green waters of the NDAC. (Last time I was there it was 7°C below the thermocline.)
1m15s into the clip, there is a nice glide from my freedive trainer Mark Harris to -61 meters.
The Mediterranean waters off beautiful Villefranche-sur-Mer is the setting for the 2005 constant weight freediving world championship. Loïc Leferme, the world record holder for his -171 m no limits dive last year, is one of the organisers of the competition that takes place the first weekend of September. The performances of freedivers have now progressed to a stage where constant weight records touch the no limits depths from the days when Jacques Mayol (the inspiration for Luc Besson's film, Le Grand Bleu / The Big Blue) pushed past what was thought humanly possible and helped define freediving as a competitive sport. I witnessed Carlos Coste set his -102 m world record in Cyprus last year, three monhts later Martin Stepanek had pushed it to -103 m. If you are in the UK and you are a new or accomplished freediver, you can join SaltFree Divers for constant weight trianing at the NDAC on the border to Wales or come to the swimming pool in Richmond for static and dynamic apnea.
Check out US patent application 20040003811 A1 filed by inventor Alan-Izhar Bodner. It describes an "electro-gill". If this apparatus works in practice it may be the biggest revolution in scuba diving since the acronym for Self Contained Underwater Breathing Apparatus was thought up. It is well known that seawater contains dissolved gases. Aquatic animals (including fish) extract oxygen from water through their gills or their skin, and they seem to do just fine. For humans, the most efficient means of breathing underwater has so far been the closed circuit rebreather (CCR). Bodner's invention uses cavitation to physically separate breathable air from the seawater. The patent application predicts that processing 2,000 l/min should produce 25 l of breathing gas (more than double my breathing rate). Directing two cubic meters of water per minute through a nozzle should be more than enough for diver propulsion, so even less oxygen is metabolised during a dive (unless you panic and hyperventilate while trying to avoid ramming into obstructions at high speed). The invention prompts two questions about its usefulness. Which energy source would be portable yet powerful enough to drive the pump and gas separation engine? The power requirements may render the device impractical if they push the weight of the unit above that of sports diving equipment, leaving instead the electro-gill to serve military purposes or supplying underwater habitats or machinery. The second question is about gas mix. In its simplest form, the electro-gill would serve up the gas mix which is dissolved in the seawater. This goes against the current trend where divers are making use of different gases' properties to decide on the best breathing gas for the target depth (nitrox, trimix etc). With filters and scrubber, the electro-gill could become a trimix rebreather fed from the gases dissolved in the water but the issue would again be one of size and weight. Despite these doubts, I would be happy to be on the test team.
Jetsam Technologies in Vancouver makes a high quality rebreather called the KISS. It arrives as a kit that you have to put together yourself. The bare minimum of instructions that come with the unit give scant advice on how to assemble the pieces; the idea being that by figuring out how to put it together you will gain valuable knowledge of how the thing works and how to service it. Something that is detailed in the documentation is how dangerous rebreather diving can be if you don't understand it fully. My KISS rebreather has taken a long time to come together into a functioning device. Plenty of excuses: Lack of time or lack of focus due to my new interest in freediving. Or because it is so convenient to take my Dräger Ray rebreather for a spin instead. But now a concerted effort has seen the unit take shape over the last two weeks. Next step is proper training. In the photo is Steve Copeland's KISS. The 1.5 liter tank of Oxygen allows for five hours of diving. The HeliOx diluent has a max operating depth of 66 meters. Spending, say, 40 minutes at 30 meters will result in a 12 minute decompression stop to wash out helium. The even better news is that nitrogen narcosis becomes a non-issue with this gas mix.