If you watched yesterday’s freediving documentary, “No Limits”, you may enjoy this talk by Tanya Streeter, a (now retired) British/Caymanian freediver who features in that film. She gave a talk at TEDxAustin in 2012. In it she talks about the sport of freediving, gas narcosis, motherhood, and plastic pollution in the world’s oceans.
Category: Nitrogen narcosis
Video (TED): Richard Pyle on exploring the reef’s twilight zone
In this TED talk, self proclaimed “fish nerd” Pyle speaks about his work studying coral reef fish that live in the 100-200 metre depth range. This depth is too deep for scuba, and too shallow for submersibles, so Pyle pioneered the use of rebreathers (he was an early adopter, in 1994) to access this part of the ocean. This is a high risk pursuit, but the diversity and numbers of new species to be discovered here is stunning.
I first heard about Richard Pyle through Monty, who encouraged the readers of his Scuba Culture newsletter to check out an article Pyle wrote about an incident of decompression sickness when he was nineteen. The article is called Confessions of a Mortal Diver: Learning the Hard Way, and Monty is right – you should read it. Pyle actually mentions this incident right at the start of his talk. Watch below:
Article: Esquire on diving the Andrea Doria
The wreck of the Andrea Doria, a luxury Italian cruise ship that sank in the north Atlantic ocean in 1956, is to some divers a sort of Mount Everest. It lies in about 70 metres of seawater, 160 kilometres from land. It has claimed ten lives to date and been the subject of several books and essays. Deep Descent deals specifically with this wreck. Shadow Divers and The Last Dive describe dives on the wreck, as well as featuring several of the regular charter captains and divers who pioneered diving on the Doria.
An Esquire article from 2000, written by Bucky McMahon (author of this article on Reunion’s shark problem), describes diving on the wreck, and attempts (as do they all) to pin down the allure of this particular piece of ocean debris. The article was written after a thirteen month period (late 1998- late 1999) during which five divers from the same charter boat (the Seeker) died on the wreck. It is written in a masculine, aggressive style that may be characteristic of McMahon’s writing, but is certainly characteristic of the sort of behaviour that seems to play (or have played) out on the Andrea Doria since people started diving her.
But how does it feel? What’s it like to know you are in a story that you will either retell a hundred times or never tell? You decide to drop down into the black hole. No, you don’t decide; you just do it. Why? You just do. A little ways, to explore the wreck and your courage, what you came down here to do. What is it like? Nothing under your fins now for eighty feet but the mass and complexity of the machine on all sides–what was once luminous and magical changed to dreary chaos. Drifting down past the cables that killed John Ornsby, rusty steel lianas where a wall has collapsed. Dropping too fast now, you pump air into your b.c., kick up and bash your tanks into a pipe, swing one arm and hit a cable, rust particles raining down. You’ve never felt your attention so assaulted: It is everything at once, from all directions, and from inside, too. You grab the cable and hang, catching your breath–bubble and hiss, bubble and hiss. Your light, a beam of dancing motes, plays down a battered passageway, where metal steps on the left-hand wall lead to a vertical landing, then disappear behind a low, sponge-encrusted wall that was once a ceiling. That’s the way inside the Doria.
Read the complete article here.
Bookshelf: The Last Dive
The Last Dive – Bernie Chowdhury
The Last Dive is a number of things: a history of how cave diving techniques came to be applied to advanced wreck diving (use of lines for wreck penetration, for example), the story of the early days of mixed gas diving in the United States, the chronicle of the close-knit bands of divers who risked their lives to explore the cold, deep waters off the north Atlantic seaboard of the USA and retrieve trinkets from the many vessels wrecked there, and a biography of Chris and son Chrissy Rouse, who were involved in all of the aforementioned threads of the tale. The central subject of the book is the Rouses’ death while (or just after) diving on the German U-boat discovered by a local dive boat skipper.
I first encountered the Rouses in Robert Kurson’s book Shadow Divers, a gripping read about the efforts to identify the same mysterious German U-boat that the Rouses perished on, off the coast of the US, and Deep Descent, which describes diving on the wreck of the Andrea Doria and features many of the same divers and dive charter operators. Their relationship is (perhaps too) sympathetically portrayed by author Bernie Chowdhury, a friend of the family.
The Rouses were extremely technically proficient divers, but their downfall seems to have been their fraught and fractious relationship that was characterised by vicious bickering and name-calling that stopped only when they put regulators in their mouths to descend into a cave or onto a wreck. Chowdhury shows how their difficult (but ultimately loving) relationship led them to doing a dive (their final one) onto the U-boat when the conditions were decidely sub par. Their choice to dive to over 80 metres on air, when they were proficient in mixed gas use, as well as what seemed to be the firm conviction of Chrissy (the younger) Rouse that he was immortal, also appears to have contributed greatly to their deaths.
Both Chris and Chrissy Rouse died of DCS – Chris died in the water within minutes of surfacing, and his son Chrissy hours later in a recompression chamber. They had both ascended rapidly without any decompression stops, from a longer than planned dive to over 80 metres, having lost their stage cylinders in their disorientation after emerging from a disastrous penetration of the submarine during which Chrissy became trapped under a fallen book shelf and a self-inflating life raft.
Earlier in the book, Chowdhury describes his own experience of very serious decompression sickness, which gives great insight into how debilitating (if not fatal) the experience of being bent can be. His enumeration at the end of The Last Dive of the serious physical conditions now prevalent among divers of his generation who have persistently pushed the envelope and, in many instances, been bent and recovered, serves as a cautionary tale to those who believe that no-decompression limits are for wussies.
As I expressed in my review of Deep Descent, I strongly disapprove of the macho cowboy attitude that seems to be (have been?) disturbingly prevalent among the divers and charters of this generation (and not limited to the United States). But Chowdhury’s book is more than an ode to the glory days of artifact retrieval and experimentation with trimix. As a history of cave diving, mixed gas diving and advanced wreck diving it’s invaluable. As a diver himself, conversant with all these disciplines, Chowdhury is able to explain in simple terms concepts that would slow down someone who hasn’t done a dive course. The book is very readable despite the technical subjects covered.
Chowdhury does not conclude that the risks taken to achieve what this particular group of divers did were unreasonable, and does not overtly criticise the Rouses for the attitudes and behaviour that – I think most sensible people would agree – contributed to their deaths instead of just a scare that might have forced an adjustment to the dive plan. While he admits to having experienced times of ambivalence about diving, particularly when he describes the strain it placed on his relationship with his wife and son and the long road to rehabilitation that followed his episode of the bends, his equilibrium surprisingly undisturbed by the loss of several friends and acquaintances to the sport he loves, and his own health difficulties.
For some more perspectives on this book and the perceived accuracy of the descriptions of the events it covers, you can read this review and this discussion.
You can purchase the book here if you’re in South Africa, and here if you’re not. The Kindle edition is available here and here.
Oh, and go sign up for some DAN insurance, please?
Enriched Air/Nitrox Specialty
If you’re a Cape Town diver, and serious about enjoying the huge range of wrecks and reefs we have here, there are two Specialties that you should seriously consider.
One is the Deep Specialty, which qualifies you to go to 40 metres. (The depth it qualifies you to go to is actually less important than the skills you will learn on the course.)
The other is the Enriched Air/Nitrox Specialty. Enriched air is ordinary air that has been enriched with extra oxygen. This reduces the nitrogen concentration, which is a good thing for two reasons.
- When we breathe air under pressure, nitrogen is absorbed by our body tissues (particularly quickly by fat). While you’re at depth this isn’t a problem, but it becomes a problem when you ascend too fast and neglect to do the required safety stops or decompression stops. The nitrogen forms bubbles in your blood, brain and joints, and you will get bent. This can be fatal, and it’s a horrible way to go. You can think about what enriched air does for you in two ways: you get extended bottom time within the no-decompression limits, or a margin of safety because if you follow the dive tables for air when breathing nitrox, you will have absorbed less nitrogen into your tissues by the time you ascend. The risk of decompression sickness is thus reduced.
- Nitrogen has a narcotic effect when breathed under pressure, and this can impair judgment and lead to all sorts of stupidity on a dive. Less nitrogen in the mix you’re breathing means less narcosis.
It’s not as simple as just putting more oxygen in your cylinder and jumping into the water, however. Oxygen is toxic when breathed under pressure (you just can’t win!) and can cause convulsions. At the bottom of the ocean, a convulsion is bad news. So while you are free to add oxygen to your breathing mix, your maximum depth is restricted by the richness of the mix you choose. Nitrox mixes are referred to according to the percentage of oxygen in the mix. Normal air has 21% oxygen: Nitrox 32 means that the cylinder has 32% oxygen in it.
The Nitrox Specialty is mainly theory – there are some formulas that you need to get to grips with, and you need to understand the two-edged sword that is enriched air. Once you’ve mastered the theory, you’ll learn how to use a Nitrox analyser, and probably do two dives on Nitrox.
As you dive more and more, your air consumption gets better and better. When you get to the point where your dives are limited by the no-decompression limits of air rather than the amount of air in your cylinder, the Nitrox specialty becomes extremely attractive. If you’re in the group of divers (such as older, or overweight) who are most at risk of decompression sickness, diving on Nitrox is a huge investment in your own safety. And finally, if you do repetitive dives (several dives in a day), diving on Nitrox will extend your total bottom time tremendously.
Bookshelf: Diver Down
Diver Down: Real-World Scuba Accidents and How to Avoid Them – Michael R. Ange
This book should be compulsory reading for all careless, lazy, poorly-trained, slapdash or happy-go-lucky divers out there. In fact, for all divers.
This book is short with lots of sidebars (I don’t like these in books – they make it hard to read smoothly). Each chapter starts with an account of a diving accident (not all of them fatal). An analysis of what went wrong follows, as well as a short checklist of what you can do to avoid a similar fate.
I was at first reluctant to read this book because I thought it might scare me, but Tony devoured it and suggested I read it. It was disturbing, but didn’t give me nightmares. Michael Ange doesn’t write in a prurient or senstational manner – he just presents the facts. He has ample experience reviewing diving accidents.
Most of the time it was really simple things that caught people out, or a cascade of trivial compounding errors or problems. Often it was ego or over-confidence that led to the problems. Controlling partners or well-meaning parents who pressured their loved ones into doing things they shouldn’t also feature strongly.
The emphasis is on training, experience and common sense – every single thing you learn in your dive courses is vital. PADI and friends want to make diving fun and accessible, and they’ve pared down the manuals to be as concise and un-intimidating as possible… So EVERY SINGLE WORD counts. This is both a good thing (no scary huge textbooks) and a bad thing (you NEED to pay attention when you read and watch the DVDs and spend time with your instructor).
Dive briefings are also important. Your local Divemaster isn’t trying to dampen the mood by warning you not to surface without an SMB – he’s ensuring that you don’t end up out at sea without a signalling device, or with an unwanted Yamaha haircut. When the skipper and Divemaster speak they’re doing it out of a wealth of local (and that’s important) experience. Pay heed.
You can get a copy of the book here if you’re in South Africa, and here otherwise. If you want to read it on your Kindle, go here. If you dive, you should read it. And you should do a Rescue Diver course.
Bookshelf: Shadow Divers
Shadow Divers – Robert Kurson
This book is gripping – I loved it. It describes the discovery and diving on a German U-boat in the northern Atlantic Ocean. It took over six years before the vessel was conclusively identified, and Kurson describes the process followed – including multiple dead ends – by John Chatterton and Richie Kohler, the two divers who persisted with the mystery long after others had lost interest.
It’s a mixture of terrifying deep wreck diving and penetration, WWII history, and personal drama that I found quite irresistible. Three divers died on the submarine before it was identified, and every imaginable diving accident – from entanglement to DCS to panic to nitrogen narcosis (a big feature, since the sub lies at about 70 metres and initially the diving on her was on air), and the constant risk of being lost at sea if you didn’t surface on the line – occurs. I still don’t think this kind of diving is for me – the dangers are too great.
I admired the determination of Chatterton and Kohler to put a name to the submarine, thus providing closure to the families of the German officers who perished on board. Their rectitude and determination not to desecrate a war grave and the resting place of nearly sixty men was admirable. It’s possible that, had they agreed to rummage among the human remains all over the submarine, they’d have located an item of someone’s personal effects that would have speeded the identification process, but they refused to disturb the bones.
The culture of American deep wreck diving sounds as though it is quite macho and cowboy-like (one group of divers wore matching denim jackets with a skull and crossbones on it), and for Chatterton and Kohler to buck that trend was a big thing.
I learned one useful thing that has stayed in my mind since I finished the book – maybe I knew it all along, but it was articulated here in a clear manner: when you run into difficulties in the water, solve the first problem completely before you try to solve a second or third one. You need to answer each problem fully when it occurs, because accidents happen when a small thing is ignored, which then combines with another problem to cause a life-threatening situation.
In the acknowledgements, Kurson mentions Deep Descent by Kevin McMurray, which describes diving on the wreck of the Andrea Doria in the same dangerous, cold, rough piece of ocean. Many of the protagonists in MacMurray’s book appear in Shadow Divers, as do the same pair of dive boats – the Seeker and the Wahoo. He also cites Neutral Buoyancy by Tim Ecott, another of our favourite diving books, as an inspiration and source for some of the decompression theory.
Unfortunately the aggressive, fiercely competitive ethos that has been allowed to fester among this particular group of divers has led to the publication of a rival account by Gary Gentile (who appeared extensively in Deep Descent). It’s called Shadow Divers Exposed and apparently refutes much of what is described by Kurson. Gentile is clearly a bitter and angry man, with several axes to grind. It does however seem possible that in focusing the book so squarely on Kohler and Chatterton, Kurson allowed it to seem as though the two of them are due more credit for identifying the U-boat than they really are, so this book should be read with a small measure of caution. I would still strongly recommend it, however – the overarching truths and events described did take place, even if a few small-minded participants and observers would quarrel over specific details.
The book is available here if you’re in South Africa, otherwise here. If you want to read it on your Kindle, go here.
Dive sites: SAS Fleur
The current Deep Specialty we are running took us to visit the wreck of the SAS Fleur last weekend. She lies in 42 metres of water in the middle of False Bay. It was a 25 minute boat ride from our Long Beach pickup on a flat calm sea.
This is the sister ship to the SAS Somerset moored behind the Two Oceans Aquarium and the rounded form is clearly visible along the length of the hull. The Fleur was sunk by naval gunfire near Simon’s Town on 8 October 1965.
We descended on the shot line and slowed at 20 metres. We were already able to see the whole wreck below us – the conditions were exceptional but it was quite dark. We stopped briefly at 25 metres to ensure everyone was in good shape without any nitrogen narcosis, dropped a little lower to 30 metres and checked again. A final check took place at 35 metres on the deck of the wreck.
The ship is rusted extensively and most if not all the decking and side plates are rusted through, giving you an extremely clear view of everything inside the shell. We found several sleeping pyjama sharks and a catshark inside one of the hatches on the deck of the ship.
The visibilty was a good 10 to 12 metres on the wreck with a water temperature of 14 degrees. There was a strong current running parallel to the orientation of the ship on the sand. Large schools of fish hung over the wreck, facing into the current.
The wreck is heavily encrusted with mussels, each of which is in turn encrusted with strawberry sea anemones in beautiful shades of pink. There are many urchins, and also some large tube worms, which really give the feel of being in deep water!
We returned to the line and started a slow ascent with a stop at 20 metres, 10 metres and finally a 5 metre stop. We deployed SMBs as we started our series of safety stops, because given the exposed nature of the site and the possiblity of seeing sharks on the way up, it was very important for Grant to know exactly where to expect our heads to break the surface.
Cecil, Clare and I were using 15 litre Nitrox 30% cylinders, and ascended with plenty of air to spare. We were entertained by seals at our safety stops, and a large group of them frolicked near the dive boat as we waited to climb in after the dive. The dive site is quite close to Seal Island, but happy and comfortable seals indicated that we didn’t need to worry about sharks that day.
This is a spectacular dive, and we were very fortunate to do it in perfect conditions.
Dive date: 2 April 2011
Air temperature: 23 degrees
Water temperature: 12 degrees
Maximum depth: 36.4 metres
Visibility: 12 metres
Dive duration: 29 minutes
Article: Wired on cave diving
I linked to this article in my review of Sheck Exley’s book Caverns Measureless to Man, but it really deserves its own post because it’s such a fascinating read. Jerry Shine of Wired Magazine describes Exley’s cave diving activities in Mexico (and his ultimate fate) while giving a readable introduction to the growth of cave diving as a sport, and scuba diving in general.
Full article can be found here.
Dive gear maintenance: Knives
Dive knives come in a range of sizes, shapes and qualities. They often have the words “stainless steel” engraved on the shaft but this more often means “a bit of stainless steel and a lot of good old steel”, the type that rusts quickly.
The more you pay for a knife the higher the quality of the stainless steel and the less likely it is to rust. I have never owned a particularly expensive dive knife so I am well versed in the speed at which the “el cheapo” knives rust. Bear in mind that the more expensive your knife, the more likely you are to take stupid chances – under the influence of nitrogen narcosis – to retrieve it if you drop it while diving… Cheap knives have their advantages!
With a new knife, I start off by washing the knife in very hot water, dry it well and then paint the metal with clear nail varnish. This lasts well and will only need a repaint if you use the knife to actually cut something (imagine that!).
It does help to remove the knife from its sheath and rinse it after every dive, but eventually it will develop some rust. You can gently sand this off, and then repeat the nail polish treatment.