Na Na Na Narcosis – A dry dive to 50 metres at the Millport Hyperbaric Chamber

After a 2 hour drive down from Perth to the seaside town of Largs we stopped for a quick coffee before hopping on to the Ferry to the Island of Great Cumbrae and a 5 minute drive to the University Marine Biological Station Millport, to meet Phil Lonsdale the manager for the Hyperbaric Chamber which is one of his roles at the station.

From Millport Dry Dive Feb 2011

After an introductory talk the victims (Sorry divers) entered the pot and placing dive computers in a tub of water and taking in a few items such as polystyrene, plastic bottles and aerated chocolate snacks, the first thing we noticed was the number of times you need to clear your ears is considerably more than when underwater also you get to see first hand how the Gas laws work ie. Charles Law “Temperature Increases = Pressure Increases X constant volume (I hope)” the temperature increases from 14 Degrees Celsius to a barmy 40 degrees once we reach the 50 metres (6 Atmospheres).

After a brief stop at 6 metres we descended and you started to notice the air was becoming thicker and at 30 metres we were unable to whistle. Phil Mentioned that the chamber in Millport is the 2nd Fastest chamber in the UK, with the experimental chamber at Gosport being faster it is possible to drop to 50 metres in 3 minutes.

As we descended past 40 metres I noticed that we all became relaxed and not so socially inhibited similar to getting a bit tipsy, in this secure environment we were enjoying the rapture of the deep, also our voices sounded like chipmunks which also added to the fun environment. (When diving in dark cold low visibility environments narcosis can also amplify any anxieties you may have during the dive, I have noticed this on several dives below 40 metres.

Once we were at the bottom I could feel the effects of the narcosis not just as much as drinking a large glass of wine while making dinner :). We had a look at the items that we had taken into the chamber; the polystyrene had been compressed and was shorter by at least a third the plastic water bottle had collapsed completely and the Milky Way was looking squashed. After 17 minutes dive time we started our ascent, Phil uses the Navy Tables which are the most conservative and are designed for only one dive per day. He brings us back up to 6metres where we stop for 5 minutes, as the pressure decreases the temperature drops to about 17 degrees centigrade and at about 30 metres and the air in the chamber passed the dew point and a fine mist appeared in the chamber for a few minutes. We then ascended to 3 metres for 10 minutes and the total dive time was 37 minutes at with a maximum depth of 50 metres.

As we got out of the chamber Phil checked our Co-orientation to make sure none of us we suffering from the “Bends” or Decompression illness. His talk was very interesting a couple of interesting facts the pain you feel in your limbs is not trapped bubbles in the joints but is the symptoms of bubbles in the spinal cord, also a discussion on deep stops and the complexities created by deep stops with different tissues on-gassing while others are off-gassing.

We all had and enjoyable day, thanks to Phil Lonsdale and his team for allowing us to use the Chamber on a Saturday and to Max from Edinburgh University for arranging the trip. Please note that only the chamber in Aberdeen in Scotland is funded by the NHS. The other chambers (Orkney, Oban and Millport) in Scotland are privately funded and only receive funding from the NHS when they treat a patient.

From Millport Dry Dive Feb 2011

For more information about the Scottish Diving Medicine and the Diving emergencies and medical advice in Scotland: call 0845 408 6008 and ask for the on-call hyperbaric consultant. In England, Wales or Northern Ireland telephone 07831 151523

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