On the evening of 21 April 2005, 10 divers from Aquamarine SAA descended on the London Diving Chamber for a dry Dive Experience. These intrepid adventurers were: Fiona, Cisco, Simon, Seb, Ben, Brendan, Stephen, Gayle, Bob and Julie.

Dry Diving you ask? Isn’t that a contradiction in terms? What is Dry Diving?

Dry diving is exactly as it sounds. A hyperbaric chamber is the perfect environment to test a diver’s ability at depth, but in the safe, water-free environment that it offers. For example, Decompression Sickness (DCS) often results from a diver’s inability to handle nitrogen narcosis and the subsequent error such as loosing control of buoyancy that result.

Currently the PADI depths of the Advanced Open Water course are perhaps not deep enough to really experience narcosis and deep diving at sea would simply be too reckless for experimentation. If a diver does experience the surreal feeling of narcosis panic can result. It is important to be mentally prepared for the feelings encountered. A dry dive is a great opportunity for a diver to mentally prepare for what can happen underwater and for technical divers it represents an appropriate place to test their kit.

On arrival we were asked to fill in a self-declaration medical form and the usual waiver form that you would associate with “ordinary” diving. Keep in mind that there remains a risk of DCS even with dry diving!

We then received a briefing explaining that: we would be accompanied by a trained chamber operator, that t he chamber would then be taken to about 3 meters where we would all be asked if we were OK. It was specifically important that we could equalise; the chamber would then quickly go to 50 metres where we would see first hand the effects of Charles’ law. We were warned that thedescent could be noisy and were asked to only talk once we were on the bottom.

The descent went fine and was indeed noisy. We looked around anticipating who would be the first to speak. It was Ben and the result was akin to an Antipodean Clanger on speed. In an outrageously squeaky voice, due to his vocal cords not being able to work in the pressure, Ben proceeded to grace us with a somewhat imperfect rendition of “Tie me Kangaroo down sport.” Verdict: Ben is euphoric at depth – not a real change there then!

In complete contrast Fiona transformed from the mad cap diver we all know and love to Miss Sensible and then shattered this new found aura of professionalism by producing chocolate bars that she had brought to 50 meters to see what would happen. Verdict on that: surprisingly very little in terms of the pressure on the bubbles in Aero. However, the build up of heat had melted one bar into a complete mess.

Now this brings us to the physics bit so Bob had better look away before he has one of his turns. The chamber dive gave us all an excellent opportunity to understand Charles’ law first had.

Jacques Charles investigated the relationship between the Volume of a gas and how it changes with temperature and he noted that the volume of a gas increased with the temperature. Charles's Law states that the volume of a given amount of dry ideal gas is directly proportional to the Kelvin Temperature provided the amount of gas and the pressure remain fixed. When we plot the Volume of a gas against the Kelvin temperature it forms a straight line. The mathematical statement is that the V / T = a constant. For two sets of conditions the following is a math statement of Charles's Law:

With only enough time remaining for the Chairman to polish off the chocolate the team were returned slowly to the surface. Deco stops were made along the way and it was finally out of the chamber about an hour after going in. LDC were then happy to stamp log books to confirm the experience.

All in all this was great fun and something that we are likely to repeat – watch the web page and newsletter for dates. There could also be a full chamber speciality on offer which will deal with even more of the theory.