The liveliest letters from the DIVER mailbag...
WHEN A WEIGHTBELT COMES OFF|
The wit and humour of Monty Halls' Deep Breath (We're Just a Load of Lemmings, December) article were great. The weightbelt with the quick release is a classic.
I was diving the Rosehill in Plymouth a few years ago with a buddy who was so busy wrestling with a crab in the wreck that his fat belly flung his belt onto his hips. The buckle caught on the wreck and popped open.
We were about 2m apart, at the end of a 40min dive, and I was cold and fed up with waiting while he terrorised the poor crab. Then he coolly handed me the belt, which he had managed to catch as it slipped off.
Everything went into slow motion. Tim had his arms and legs wrapped around some steel members on the wreck and was screaming at me through his dv.
I must have been narked, as I couldn't work out what to do with the weightbelt. I started by putting it round his neck on the back of the pillar valve - don't ask why - then realised that it would fall off on the ascent. "I wouldn't have done that," I hear you cry. Right - ever laughed at someone who got a simple question wrong on a quiz show?
Eventually I wrapped my legs around him while dumping all the air from both of us as we were sucked off the wreck by the changing tide. We touched down in a heap in the silt below. I managed to wrap the weightbelt back round his waist so that he could do the buckle up and we controlled the ascent, with him apologising and me swearing at him all through the deco stops.
We later agreed that we had both had a lucky escape. On a drift dive there would have been little I could have done in the time. Filling his suit with sand, or holding him only to have to release him near the surface would have been no good.
What is easy to discuss at the surface can be like undertaking The Crystal Maze under water. I couldn't believe how slow I had been to react.
Diving with a good calm partner with whom you have built trust over many dives is a key factor. It took guts for him to release his grip from the wreck into 2m viz with a running tide while falling off the edge of the wreck as I fumbled about.
Training is also vital. Rehearse situations and discuss with your buddy over a pint how you would react to various possible situations. Have a get-out plan and if, as with the weightbelt, the quick release is flawed, change it. You can cut a belt off in an emergency with a big knife, but lose one and time will work against you.
Our conclusion, before it became possible to buy a buckle-and-pin model, was to put two buckles on the weightbelt.
Jay Delves, Winchester
John Bennett's diagnosis disputed
I read with great interest the article by John Bennett in which he took us through his world-record dive (How I Dived Past 1000ft, January). As a fellow technical diver and underwater adventurer, I congratulate John for not only achieving his target depth, but for doing it in a carefully planned and correctly executed fashion.
Competent technical divers understand that there is a potentially vast difference between just doing a dive and setting it up properly. It seems that John has set an excellent example for those who will follow.
However, I would dissent on what I consider an important issue arising from his story. I have significant doubts about the diagnosis of inner-ear barotrauma (IEB) that John cites as the explanation for his profound vertigo, nausea and vomiting during the ascent. His story conforms exactly with the classical natural history of inner-ear decompression illness.
Vertigo and nausea during ascent from a deep helium dive when gas switches are being made to mixes with a higher nitrogen content are characteristic of IE DCI. This is a widely recognised risk of helium bounce dives employing progressively richer nitrogen-containing mixes (or ultimately air/nitrox) to accelerate decompression.
The lack of other neurological problems reported by John is entirely consistent with IE DCI, as this unusual mechanism can give rise to "pure" inner-ear disease with no other adverse effects. IEB can produce similar symptoms but it is unusual for these to occur during ascent, and IEB with symptoms as severe as those reported by John usually does not settle quickly.
In contrast, IE DCI frequently settles spontaneously, particularly if there is prolonged oxygen breathing during the final phase of the decompression or after leaving the water.
The distinction is important. IEB could be "written off" as a random event bearing little relationship to the nature of the dive, but IE DCI is a predictable though uncommon consequence of the type of dive John performed.
His skills and contingency planning saw him through the event, but those who follow in his footsteps might want to take heed.
Dr Simon J Mitchell, Brisbane, Australia
John Bennett replies: It's good to get feedback from someone with Simon's qualifications in hyperbaric medicine. From what he says, it's clear that my problem could well have been an IE DCI, though I still believe it was not, and this is not a matter of denial. Most IE DCIs happen, to my knowledge, when the diver switches in deep water from trimix to air or nitrox, causing a sudden change to a much higher nitrogen level.
My switch was from a trimix 16/45 to a trimix 21/35, and the ppN2 went from 2.94 to 3.34, so I went from an equivalent nitrogen level of 27m to one of 32m.
Also, the recovery was not spontaneous. The symptoms improved greatly during the dive, but the tinnitus and balance problems lasted for about a week. However, within 20 days I was back running trimix programmes, and into my full training regime, and within four weeks was running 100m dives with a salvage team. I intend to communicate with Simon, however, and hope that between us we can come up with some answers about profiling in general.
SHUTDOWN WITH A POSEIDON
I want to express concern over John Liddiard's article You Have 35 Seconds Starting Now (January), about how fast a manifolded twin cylinder with an isolation valve can be shut down in an emergency.
This article needed writing but I feel it is misleading, as a very high percentage of technical divers use Poseidon regs, which deliver about twice the air of the one used in this test.
I tried free-flowing my Poseidon Jetstream on top of the box at Stoney Cove at 32m and lost 100 bar in less than 25 seconds. For Poseidon users the times in your mag are about double what you really have. This is why I now dive with my isolation valve closed.
I know the text says these figures are not foolproof, but not everyone will read the whole article. Keep up the good work in 2002.
John Liddiard replies: I congratulate Paul on taking his own measurements and adjusting his practices as a result. That's the kind of rigorous analytical approach to safety all technical divers should be following. I like Poseidons and have a couple in my collection. However, the Scubapros we used for the article are more typical of the regulators used with manifolded sets.
We also made comparable measurements with assorted Aqualung and Apeks regs. It's worth noting that one reason why the DIR movement precludes Poseidon regulators is their high free-flow performance.
Driving can be dangerous too
When I was 17 I learnt to drive. I could have been taught by my father, who had years of experience behind the wheel and was a very patient man, but he suggested that I go to a driving school and pay for tuition.
None of my mates who had already passed their driving tests ridiculed me for going to a professional instructor. Nobody ever remarked that the instructor was only in it for the money.
I passed my test. I had fulfilled the minimum standard deemed to show that I was a safe driver. I had never been on a motorway, driven unaccompanied or experienced the many situations which the next 30 years or so would occasionally contain, yet I was given a full licence.
I could, had I wished, have supervised other learner-drivers or even taught them to drive - from scratch!
My driving school never suggested that I should take further courses to broaden my experience or improve my skills. I have never heard from my instructor since the day I passed my test. No one has ever found this situation undesirable or strange, or criticised me for it.
A few years ago I learnt to dive. I went to a diving school and took lessons with a professional diving instructor. I paid for his time and effort. That's where the similarity ends.
True, when I became certified as a PADI Open Water Diver I lacked experience that only the ensuing years have provided. But my diving school encouraged me to broaden my experience through continuing courses in addition to regular diving. As you would expect, I continued to pay for the time and effort of the instructors.
I would like to say this arrangement met the same response from fellow-divers as my driving education brought from fellow-drivers. Not so.
A mercifully small minority of UK divers seem to regard the PADI system of diver education as inferior to other methods. Their arguments always seem to include the fact that PADI and its instructors receive payment for teaching divers to dive. Through some twisted logic this equates to PADI teaching being inferior to that of non-commercial organisations. I don't hear of driving schools being criticised on such grounds.
Today I am a PADI instructor. I guess that my driving instructor all those years ago did not choose his career simply for the remuneration, but because he was enthusiastic about the job. But even if he wasn't in it for the money, why on earth shouldn't he have earned his living from it?
Victor John Harris. Birmingham
The rough side of redundancy
I just read January's Diver and noticed several articles referring to "redundant" air supplies. The term "redundant" has particular relevance at the moment as my job is "under review", so I am facing the possibility of redundancy.
This makes one feel unwanted, so applying the term to spare air seems inappropriate. My dictionary says: "Redundant: superfluous... deprived of job... no longer needed." If my air supply failed for some reason, I would look on my pony cylinder with great love and affection.
Why do people insist on calling a potential life-saver "superfluous" or "no longer needed"? My pony cylinder is redundant only if I leave it at home. Let's rid ourselves of this derogatory term and use "independent air source" or something more appropriate. In the end, we are limited only by our imaginations.
Tony Hodge, Preston, E Yorkshire
Outing the coral whitewashers
I was deeply concerned and depressed by Charles Sheppard's article on coral-reef destruction in various parts of the world (Rubble Trouble, December 2001).
As frightening as this is, I find perhaps equally alarming Dr Sheppard's inability to publish the results of his research, so as to "name and shame" the guilty countries.
What power does a guilty authority hold over Dr Sheppard that enables it to prevent publication of his findings in Diver, or even in a presumably respectable scientific journal?
How can he permit his professional and academic integrity to be compromised so completely?
Unless all of us with an interest put pressure on polluting, over-fishing, over-collecting or otherwise destructive nations through meaningful action, we will lose these reefs. Dr Sheppard states that he is "surprised that so few audiences are aware of the threats to reefs, or that a third of the world's reefs have been destroyed". How can he be, when he feels unable to let relevant interest groups know what is really going on?
Instead of, as he suggests, just letting tour operators and authorities know that we have discovered the full extent of damaged reefs at our holiday destination when we get there, would it not be infinitely more powerful to let them know in advance and not go in the first place?
The official from the unnamed small island state mentioned in the article, who observed that "it could stop divers from coming here", might then get round to cleaning up his act.
Peter Gadd, London
Charles Sheppard replies: It's common when asked to carry out research on a grant or contract to have to sign a "can't publish unless permission is expressly obtained" clause.
We could decline to do the research, but at that stage we might not know whether the site is superb or a desolate mess or toxic dump! The example I gave (one of many possible) was an incidental finding arising from research on something different.
You suggest "naming and shaming", and my instinct to do exactly that has got me into trouble more than once. It is said that guiding, without causing embarrassment, is a better way to go with governments or multi-government agencies. I don't always agree, but I reckon I do win about half the time.
Being university-based, I am probably a lot freer than many colleagues. I also edit a marine-science journal which publishes the work of several hundred scientists each year, and integrity has to stand highest in my own book.
If you did boycott a site where, say, dodgy government officials' policy had caused people to have to abandon their fishing villages, there would probably still be enough unknowing divers and tourists to keep that sector going full swing. Publicity to the extent possible may be the most fruitful way ahead in many cases, but our media is not always attentive to such things.
Depriving an already-deprived community might also have the opposite effect to that intended. It's a complex issue; my intention was only to air reef damage in a popular magazine.
The postman rings twice
I bought a wetsuit from the Weymouth-based company O'Three as a Christmas present for my girlfriend. Unfortunately, the courier company decided to deliver it to a random punter standing in the hallway of my apartment block who, not surprisingly, signed for it with a false name and made off with it post haste. Christmas had come early for him!
After several conversations with the courier, which was particularly unhelpful, I called the guys at O'Three.
The result? A replacement suit arrived the next day - at my office! I don't know about star letter, but I would have thought these guys deserve star retailer status.
Dr Ben Cresswell, Dundee
War-grave wreckers evil, not sad
Louise Trewavas asks readers if they are "fed up with hearing about war graves yet" (Trewavas, January 2002). So why did she write a long article on the subject recently?
She draws attention to an unenlightened Ministry of Defence attitude towards war graves prevalent up to 20 years ago, yet fails to acknowledge that this has changed radically in the intervening period, while that of a significant minority of sport divers has not.
By harping on about ancient history, she provides moral succour to today's beleaguered war-grave wreckers.
She may think them "sad, but not evil" but civilised society does not. Those who knocked the hatch-pins out of the submarine A7 while trying to gain access have yet to be arrested, but I am told their names are well-known in Plymouth circles.
Ask the families of those lost on the A7 who still live in the area if they think such people are just "sad". Post-Amnesty war-grave wreckers are criminals, those who assist or shield them accessories.
As reported in the last issue, the current pro-designation campaign is reaching a satisfactory conclusion. Accepted diving practice is now that war graves are not entered or disturbed; good relations have been established with the training agencies; information is regularly offered by divers to the MoD police. UK sports diving is climbing out of the moral morass into which it had slipped.
Yet Ms Trewavas seems determined to push us back in again by trivialising this sensitive issue. She should show some humility, apologise and stay off such a sensitive subject in future.
Rev Andrew Phillips, Friends of War Memorials
Who says it's cool to be cold?
I read with horror the They Think I'm an Alien letter in the January Diver. Anyone who states that drysuits are for wimps and then dives in 4°C in a wetsuit is a liability to himself and to others. I would refuse to buddy this person on safety grounds.
Hypothermia creeps up on you, and anyone too macho to heed the early signs will soon be in big trouble. Typical results are a loss of energy, which increases air usage, and general reduction in co-ordination, resulting in inability to react swiftly to emergencies such as free-flows or uncontrolled assents.
Black-outs are also common, and potentially fatal under water. Hypothermia is a stand-alone killer with no regard for physical condition.
So am I a wimp? Yes, I am the wimp in the dry/semi-dry suit with the big red whistle hanging off his BC next to the sausage marker, Z knife and pony tank attached to his single, who wishes that he could afford to buy a personal location beacon.
But I reckon that if after diving the Stanegarth in January we compared our wedding tackle, mine would be bigger than his.
Those people on the RIB in the Channel were not looking at him like he was an alien; they were looking at him like he was an idiot.
Mark Chase, Detling, Kent