Jack Ingle is the BSACs Technical Diving Adviser. He is a BSAC National Instructor, an IANTD Technical Instructor, a TDI Tri-mix instructor and co-author of NSAC nitrox courses.
I recently sat in on your equipment presentation at the London International Dive Show. I found it very interesting and your if it works for you, then do it! approach was enlightening, after being told for many years: You must do it this way! One thing you did not mention, however, was the technique of inverting cylinders to make access to the cylinder valves easier - what is your opinion of this system
Clive Peyton

    My apologies for not mentioning inverted cylinders, because this is an important part of equipment configuration and needs explaining.
    I am also pleased to hear that you like my open-minded approach to the subject. I am a great believer in equipment configuration being subjective, because what works for me might not work for you for any number of reasons, not the least being something as simple as differing physical sizes.
With inverted cylinders sitting correctly on your back, you can quite easily put your hands behind you to turn cylinder valves on and off, as they will now be situated at lower back level. I tried this technique a few years ago but it didnt suit me as I am quite short, and found that inverted 12 litre cylinders sat very high behind my head once the valves were in the correct position to allow access.
    Many divers use cages across the top of cylinder valves to protect them when inverted.
These cages were originally designed for the purpose, as they make it easier to stand the cylinders up and at the same time protect the valves from knocks.
    A slight problem with inversion is the routeing of hoses. They need to be longer and, travelling upwards, can be a little messy across the chest area. However, with a little thought and some strategically placed surgical elastic, this problem can be solved.
    Some thought should also be given to the wearing of side-slung stage cylinders, as these can cause problems in getting to the cylinder valves on the inverted back-mounted set. Again, the extent of the problem varies from diver to diver, and if you have long arms you might well not find it causes difficulties.
    Give it a go if you think it could suit your style of diving. Keep it simple at first, try it out in the pool and then add extras such as stage cylinders to make sure you can get to the valves comfortably.
Take a deep breath and think
I have been carrying out deeper and longer dives over the past two years to build my experience slowly but I am concerned that I become quite nervous before a dive. Is this the case for most divers
Ian Gleeb

I cant speak for all divers but it is certainly true in my case. Dont put nerves down as being a wrong emotion. I believe that a small amount of nervous energy is very helpful towards our overall survival, making us more aware of the potential dangers in the environment we are about to enter.
    This nervous energy should make us carry out the equipment checks we need to do and think about whether our practical skill levels are good enough.
I spend a lot of time practising the skills I need to survive under water, and this is important in ensuring that you have the correct mental attitude.
    If things do go wrong under water, I am sure you will agree that stress levels can build very quickly. Unless you can control them the situation will get rapidly worse. The initial problem in any stressful situation is increased breathing rate and I use this as a guide. I try to keep my breathing rate relaxed at all stages of a dive, and should it increase, my main objective is to get it back to relaxed.
    Think of something simple, such as a diver swimming along a wreck and into some fine fishing-line or net. The initial response of many people will be to start struggling to get free, which of course makes matters worse and causes the diver to become more entangled.
    He becomes stressed, his breathing rate increases, his body starts to produce more carbon dioxide and the more he produces the more his breathing rate increases. This makes it harder for the brain to function properly and for the diver to free himself. In the worst-case scenario, the diver can suffer a CO2 black-out and drown.
    I would recommend another course of action from the moment of entanglement. Keep still, hold onto the wreckage, stop using energy and take three long, deep breaths. This action is enough to get your breathing rate under control, reduces stress and provides a calmer situation in which to tackle the problem.
    This might sound very simple, but the link between the physical side of diving and the correct mental attitude is tied in very closely with breathing and breathing techniques.
    On technical diving courses I spend a lot of time on this topic, running specific underwater drills to get divers to think about the correct way to breathe. It is the key to underwater survival.
Lines or lights
Our dive team has started carrying out wreck penetration and understands the importance of using lines to make sure we can find the entry/exit point. Some of our divers dislike lines under water as they can cause entanglement. Are there any other methods
Richard Keynes

    One straightforward technique is to use lights. As divers penetrate further into the wreck, lights are placed at regular intervals and as high as possible to ensure good cover. The intervals depend on conditions inside the wreck and the layout. If the site is dark but not too silty they can be further apart, as long as the diver can easily see the next light in the sequence.
One risk is light failure. This system is generally fine until you have a very silty site, when a fixed datum line is a must.
    My own preference is for running a line from a reel, but I do agree with your divers that the last thing I want to see inside a restriction is loose line.
    This can, however, be avoided by using specific techniques, and wreck-divers can learn a lot from cave-divers, who have been using lines for years.
    Always use one master line in and out of the wreck. Dont allow lots of divers to use their own lines on the same route, as this will lead to tangles. If the master line can be laid as a permanent line this will also help, and all divers can follow it.
    When reeling into the wreck, make sure the line is taut. Avoid any loose line floating around or drooping to the floor.
    Regular tie-offs will help to keep the line taut and tidy. When making one, be aware of sharp pieces of metal that could cut through your penetration line - theres nothing more stressful than coming back to a loose end!
    If you are following a permanent line, ensure that you always know where it is but dont use it to pull yourself along. Check the quality of the line as you swim along it. It might have been in for some time and could show signs of wear.
    Many divers use thin lines on reels. These are quite strong, but I prefer a much thicker line for wreck-penetration, to avoid chafing and breakage. For more permanent lines, 5mm nylon is very effective.
    If two divers are entering the wreck together, make sure the diver using the reel leads in and is the last out. In this way the buddy can always be next to the line and they will not separate.
    Also think about finning technique inside the wreck. A simple frog-kick causes less turbulence. Another useful technique is to look regularly behind you to observe the route out (pilotage) and check that visibility is acceptable.
    Check the stability and strength of the wreckage. Remember, it has probably been rusting away there for years, and you dont want it collapsing on you.