Saturday, 6 September 2008

Tech 2 Course Report: Day 2

Day Two

After decamping from the NDAC last night and driving to Plymouth, we had high hopes for a week's diving in the sea for a change. Alas, it was not to be. It was, to be fair, blowing it's nadgers off today in Plymouth, with the forecast for the week getting worse and worse. However, seeing as we had the boat to ourselves we went out anyway, especially as we only needed 10 metres of water.

so we dropped into a ridiculous current, in terrible viz, and attempted to hold station carrying 9 stages between the three of us, and perform v drills, S drills and bottle rotations. A few steps into my valve drill Howard had had enough and called the dive. I did a flow check of all my valves (now including the three bottles and the argon bottle) and we ascended. On the surface it was clear that Rich was having as hard a time watching us as we were performing, but we decided to try and get in closer to the fort and see if the current eased up. It just didn't happen. After a little while, the dive was called and we got back on the boat. Getting off and on the boat is a bit ttoo much like hard work to be buggering about in 10 metres. Howard suggested that we skip the remainder of the course and jump immediately in on the Affric at 70 metres, with the logic that anyone that survived the dive should be given an automatic pass. Luckily for us, Rich decided that this would probably not be the best of plans, so we headed back to Aquanauts to make the mst of the remainder of the day by covering theory.

So, into the classroom we went, and discussed minimum deco as it is affected by having a bottom stage. strategies for different bottles including the use of additional deep deco mixes, and how these affect minimum gas. Tech2 adds a level fo complexity in the theory to the point where there simply are no right or wrong answers. there certianly is no GUE big book of rules about how deco is conducted or how gas strategy is managed. Rich simply enabled us to discuss all the options and come to our own conclusions. This course is all about making you think for yourself, rather than try and provide you with answers. It was a very interesting discussion, and moved onto decompression illness and oxygen toxicity, and what options are available - or indeed simply not available- when things occur at different depths. For the example, GUE's approach to Oxygen management is that the only gas on which we ever push the PPO2 to 1.6 is Oxygen at 6 metres. In a freakish coincidence, we train to lift unconscious divers from 6 metres. The deeper the decompression mix, the lower the Max PPo2 is on it. none of them reach 1.6. The discussion went along the lines of that we reckon we'd have a fair shot of lifting a toxing diver from the shallows, but the toxing diver at 70 metres is probably going to die. This took the discussion back to the reasoning why we are so anal about gas analysis and the gas switching procedure requiring a team authorisation as the final check in about 6 to make sure the gas is safe for that depth. We discussed how to handle hypoxic mixes when getting on and off the boat, and why we always ascend on Oxygen, and never on backgas.
The discussion moved around the managagement of gases to the treatment of bends, and current thoughts on immediate treatment of DCI with heliox rather than Oxygen. The two Riches wee bang up to date with the lastest research emerging in the area of decompression, and as all three of us find the topic fascinating, this went on for some time. we also discussed tweaking and playing with the deco, what areas can be played with, and what areas should be left alone. We planned out a 100 metre dive, reminding us that Tech2 gives you a set of tools you can use to risk analyse and plan pretty much any Ocean Dive, rather than being a fixed set of rules to be obeyed. More and more, the message was "what would you guys do and here's some ideas to choose from", rather than "this is the way we do it".

The discussion continued over dinner, although the weather made frequent visits to the list of topics on the table. The weather does not look good for the remainder of the course. The plan for tomorrow was to do 2 dives, a shallow skills dive to 10 metres, and then a progression to 25 metres where Rich could mess with us, and see more of an ascent. Personally, I don't think we're going to have any more joy tomorrow than we did today diving wise, but we're learning a lot anyway, and having fun.