Lookback : Nitrogen narcosis research in 1966
IN 1966 THE NORTH SEA OIL AND GAS BONANZA WAS JUST beginning . Divers were much in demand and anyone with 50 dives in their logbook could find a lucrative ( but dangerous ) career in the industry . Dives were routinely down to 50 metres on air with 200ft ( 65 metres ) usually regarded as the limit without Heliox . Heated suits had not been invented ; diving bells and on-deck recompression facilities were rare .
Not surprisingly , there were a lot of accidents and in an effort to understand what was going wrong , the UK Government tasked the Medical Research Council ( MRC ) to gain an understanding of the effects of nitrogen narcosis at depth .
In response to this challenge , Dr Alan Baddeley of the MRC Applied Psychology Research Unit at Cambridge put together a project in the summer of 1966 . Using teams of students with basic diver training from RMA Sandhurst and HMS Manadon , tests would be conducted on land , in shallow water , at 30 metres underwater and at 30 metres in a pressure chamber . The objective was to understand the degradation in performance associated with nitrogen narcosis . The tests would be conducted in Malta , where the weather was more dependable , and Britain still had a substantial Naval Base to support the project .
So it was that I , along with two other Cambridge students , arrived in Malta in August 1966 to support Dr Baddeley in his experiments . I had started to dive at school in 1963 so , by the standards of 1966 , I was quite an experienced diver and relished the chance to dive in warm water , with free board and lodging .
Our tests took three forms : 1 . Digit copying , where subjects copied digits across from one side of a formica sheet to another 2 . Sentence comprehension 3 . Manual dexterity , where subjects transferred nuts and bolts from one side of a drilled plate to another Each test was done on land , in shallow water and at 30 metres . We quickly discovered a number of problems with the test
Picture shows ( l-r ) Dr Alan Baddeley , Andy Williams and John Hawkeswell Curtis about to dive for a test session
regime , the biggest being that , with a bottle of whisky in the NAAFI at the Naval base costing less than £ 1 , our subjects were heavily influenced most days by a different form of narcosis ! We solved this issue by insisting on a 24-hour drying-out period before testing commenced . This largely worked , except for one or two candidates who kept taking ‘ snifters ’ when they should have been dry . The next problem was that , although most of our candidates were officer material , some of them couldn ’ t do the sentence comprehension exercises on dry land , let alone at 30m !
Eventually we got the tests under way , but as anyone who has ever attempted such research will know , the detailed logistics were fairly daunting . We timed dives with watches , but tables for multiple dives were almost non-existent ( this was 22 years before the BSAC ‘ 88 tables , and many years before the first dive computer ). Hence , we added extended decompression stops for second and third dives . This would have worked fine , except for a particularly officious sergeant who timed every dive and dropped a recall thunderflash into the water , near our decompression stop , when he considered we should all be up !
Our equipment was typical of the time . My 80 cu ft cylinder was bought from a scrap merchant when they grounded the Valiant bombers . It was tested and re-valved , but it pumped to only 120 bar . We timed our subjects with stop watches in huge waterproof cases ( see photo ) and wore sailing lifejackets in case we needed some extra buoyancy .
The results of the trials were fascinating and remain relevant today . Dr Baddeley ’ s research found a very significant link between nitrogen narcosis and anxiety levels . Hence , the existence of the ‘ Incident Pit ’, where you are having a great dive at 40 metres when something goes wrong and a huge burst of adrenalin hits your system . Suddenly your head spins , you can ’ t think straight and a wave of panic sweeps over you … at exactly the moment when you need to think straight . ANDY WILLIAMS , BSAC No 13878
Covid : Don ’ t be a denier
AFTER A SPELL SUFFERING FROM A Covid-19 infection , I ’ m just starting to get negative test results and have been thinking about my next steps . I ’ ve been fortunate to have had a relatively minor experience , and of course I ’ m looking forward to getting back in the water .
Meanwhile , we are approaching the time of the club ’ s renewal , and I ’ m thinking about those tick boxes on the renewal form . It is all too easy to tick ‘ no ’, and try to keep it all quiet .
You may tell yourself it was just a cold , and that you feel fine . If you do , you are in denial . You are also uninsured . The correct advice is to go and see a diving doctor to pass you as fit to dive . Initially I thought , is it worth the bother ? Actually , having read up a little , it really is ! Coronavirus can affect a number of organs ; it can quietly damage your heart without you even knowing . Am I arrogant enough to think I know more than a dive physician who has trained for many years ? The answer is no . I will be ticking ‘ yes ’, not denying my coronavirus . I have already booked an appointment to see a diving doctor at the Rugby Chamber , for £ 80 .
Anything else is lying to yourself . I am a very experienced diver , but I am fallible . If you want to do the diving , make sure you are physically and mentally up to it . Be safe – the water is not the place to find you have a weak heart . MIKE SMITH , Burntwood SAC
• The latest guidance on post-Covid diving can be found in this issue ’ s HUB section – Editor .
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