Nitrogen narcosis

Wreck specialty course… Part 2

Tami, Kate and I are busy with the PADI Wreck Specialty course, and did our third of four dives on Sunday 21 November. It was miserable weather, pouring with rain, but Kate demonstrated the virtues of organising a rental car with ample boot space.

Dive 3: SAS Good Hope

The SAS Good Hope is one of the five ships scuttled in Smitswinkel Bay. This was the second dive I’ve done on it. (The first one involved an unfortunate case of nitrogen narcosis – I had to briefly stop my descent because I felt it again this time, but nowhere near as badly.)

Strawberry sea anemones on the SAS Good Hope

The water was a chilly 13 degrees at the bottom, and while the visibility was excellent – perhaps 10 metres – it was very dark. The wreck is spectacular, of massive dimensions (94 metres long) and with large sections caved in. There are numerous bits of metal to swim under (we did try one or two under Tony’s instruction) and overall it is incredibly dramatic. The darkness, however, meant that even though my eyes could see the entire structure in front of me, my camera couldn’t see more than a foot or two. So the only pictures that came out were of a macro nature.

Our skills on this dive involved use of a reel and line. We tied off the reel on the wreck, and then swam into the current, keeping it tight as if we were going to using it in penetration. We turned two corners and tied it off each time. I really do not like the way I feel at depth – I feel noticeably stupid – but I was quite proud of our performance.

We did a good safety stop in very green murk, and deployed an SMB from seven metres or so. There was a fairly large swell so surface conditions were not ideal, but I managed to keep my breakfast down which pleased me no end.

Bookshelf: Cannibal Adventure

Cannibal Adventure – Willard Price

Willard Price is an adventure novelist who wrote a series of children’s books about the Hunt brothers, Hal and Roger, and their travels to various exotic destinations collecting animals for sale to zoos, circuses and the like. His titles include Tiger Adventure, Lion Adventure, African Adventure and Gorilla Adventure.

The books were published between 1960 and 1980, and are thus very dated (and mysogynistic, and racist, and parochial). Despite this, I read the series over and over as a child, repeatedly taking the books out of the Vredehoek library.

I don’t think I was particularly aware that his generalisations about women, African tribesmen, and the role of men in society were possibly offensive and narrow-minded. What was wonderful to me were the descriptions of the various animals the boys encountered, the idea that a 14- and 19-year old could capture a tiger (or silverback gorilla) alive, and the descriptions of exotic destinations.

I’m re-reading the series now (a fit of nostalgia overcame me when my sister and her husband announced that they are expecting a baby boy in March 2011… I immediately started thinking about the books I would read to him) and loving it.

Cannibal Adventure was published in 1972, which is around the time when the design of the BCD was being fine-tuned, but I don’t think they were yet in common use. It isn’t strictly about diving – it’s more about the boys’ interactions with a tribe on Papua New Guinea, and their efforts to capture local wildlife for their father to sell to zoos. However, they do go scuba diving in order to capture a family of dugongs (manatees).

I have to share this passage – there is so much to love in here!

Donning their scuba gear, which consisted of tanks, masks, weighted belts and flippers, the boys sank into the warm waters of the Arafura Sea….

The boys went back to the depths. This time they descended into a gorge two hundred feet deep. It took some stiff swimming to get to the bottom against the pressure of the water and when they got there Roger was tired out. The over-exertion gave him an experience he would never forget.

He was overcome by nitrogen narcosis. It is also called rapture of the deeps.

Just a hunch, but I don’t think Mr Price ever dived himself. There’s almost NOTHING that is positively buoyant at 67 metres…

There’s also no mention of how long it took to ascend, whether they did any kind of decompression stops, and how quickly they must have used up their gas at that depth. To give Mr Price some credit, a lot of the safety precautions we take now are fairly recent inventions… Jacques Cousteau and his team did some amazing cowboy stunts in the 1940’s and 1950’s with the new aqualung!

If you want a copy of this masterpiece (and it’s highly entertaining, I promise!) you can get it here if you’re in South Africa, otherwise here. If you want to read it on your Kindle, go here. I will review two of Price’s other books, Underwater Adventure and Diving Adventure, in forthcoming Bookshelf posts.

On a dive this past weekend to the SAS Good Hope in Smitswinkel Bay I had the pleasure of experiencing nitrogen narcosis for the first time, and it wasn’t pleasant. I was diving on Nitrox 34%, doing my 70th dive, and was with Tony, Kate, Tami and Justin. The surface conditions were magnificent, I was feeling well rested and looking forward to another visit to the Smitswinkel Bay wrecks. The visibility was not great – water was very green, rather cold (14 degrees) and we could see maybe four metres maximum.

Tony and Kate were coming down very slowly because her ears were hurting. They had to ascend for a while and come back down, so I continued my descent on the shot line with Tami and Justin. We were – I am pretty sure – going quite slowly, because the skipper had let out a lot of line and large portions of it were almost horizontal in the water. At about 25 metres I started to have a hot, lightheaded feeling that felt a bit like pins and needles in my scalp. It felt like my field of vision was narrowing (even more than it usually does on deep dives), and that I was about to black out. I couldn’t think properly – didn’t feel good.

The solution for most diving problems seems to be “ascend a few metres and wait for the effects to dissipate”, and that was all I could think to do. I grabbed the line – took several tries – and went up about three metres, hoping like heck that the feeling would pass. My intention had been to descend to the deck, which is at about 30 metres, and explore there, but Tami and Justin, who were on air, rocketed down to the sand far below. I could see Tami spreadeagled like a starfish metres below me, and wasn’t even sure she was conscious (I have a vivid imagination). If she was feeling the same way I was, there was no way I could go and fetch her and slap some sense into her until my head cleared. It was at this point that I started to feel quite strong anxiety, also a symptom of narcosis.

Fortunately after a few seconds (I think – hard to tell how much time passed) I started to feel better, and resumed my slow descent. This time I got past 25 metres without feeling strange, and was able to go all the way to 30 metres comfortably. I had reached the deck of the ship, but was reluctant to go further in case I started feeling odd again. I was also very cognisant of not exceeding the maximum depth limit for the Nitrox mix I was using (34% allows you to go to a maximum depth of 31 metres and an ABSOLUTE maximum of 37 metres). Then I tried desperately to get the attention of my two buddies to tell them to come up a bit so that our dive time would not be too short and so that they’d have enough air to enjoy it!

After the dive I floated on the surface with Kate and Justin, laughing like a drain. Probably unrelated to the narcosis and more just relief that everyone had surfaced safely… But Justin said he wanted some of whatever I was breathing!

Chilling on the surface in Smitswinkel Bay, looking like a spaceman

While I didn’t particularly enjoy the experience of being narced (if it was indeed that and not a mild case of oxygen toxicity – the initial symptoms are similar), I am glad that I now know what it feels like, and that the recommended solution – ascending a couple of metres – works, and fast. I’m also relieved that my brain still worked enough to implement that solution. This wasn’t my first deep dive, it wasn’t the deepest dive I’ve ever done, I am not a new diver, and the descent wasn’t ridiculously fast… So I guess this can happen at any time. The causes don’t seem to be terribly well understood. I’ll chalk it up to experience.