In recent times, the term technical diver has become mis-used, as scuba diving in its self is full of technical knowhow and calculations.
In 1980, there was no mention of mixed gas, nitrox or trimix, and in recreational diving has only come into play since the mid ninties. Due to the fact that you were venturing into a world where no normal minded person cared to enter, you required a huge amount of “technical training”.
Diving computers were unheard of and all of the diving was carried out by stringent meticulous timing using a watch. This procedure is almost identical some twenty years by the Trimix diver using a cocktail of air and helium.??
Today there is a minority who would claim to be technical divers, however all scuba divers are to some point technical divers.
The term was first used in the USA to differentiate between the individual, who went on holiday, learned to dive and thereafter was quite content to keep at a depth of between 10 to 30 mtrs, using only air as the breathing gas and using the buddy system.
On the other hand, the mixed gas diver went beyond the thirty metre limit and as such used equipment with built in redundancy, which ?made him self sufficient in the event of an emergency. In a huge number of instances the technical diver actually dives solo. Some technical divers dive with Jesus.
Recreational Divers
These Divers could be classed as non technical.
These divers like their diving as simple as possible. Everything is simple and basic, as is their knowledge. They rarely dive in excess of 20 mtrs.
Visibility has always got to be a minimum of 30 mtrs and the water temp at a minimum of 25 degrees.? These divers seldom dive in Irish waters.
Normally leisure divers do not dive deep enough or long enough, so in the event of a problem during their dive; they can always take the “elevator” straight to the surface without having any problems during or after the rapid accent.
Nitrox Divers
Nitrox made its entry into the mainstream some five years ago. Many people did not quite agree with this type of diving as they were only aware of the dangers and were not aware of the benefits of Nitrox. I was known as a Technical Diver, due to the fact that I was using a gas that was not air (21% o2).
Through time, it was seen that this increase in the partial fraction of oxygen performed the following:
1: Increased bottom time.
2: Decreased the like hood of decompression sickness.
3: Due to the increase of oxygen in the body, after the dive the diver felt like he /she was on steroids, due to the amount of energy in the muscles in the body
We normally breathe air (Nitrox 21).By increasing the fraction of oxygen in the "air" we breathe (nitrox 21) this ?reduces the proportion of nitrogen in the air that we breathe. When diving with nitrox there is less chance of narcosis and decompression illness.
This increased fraction of oxygen in the breathing mix has one main point that must be strictly adhered to. If a diver decends too deep on the wrong percentage breathing mix, this may lead to a convulsion, which in itself is not life threatening. However in the underwater environment that the diver finds himself or herself in the consequences can be fatal.
The added oxygen in the nitrox mix implies the deeper you go, the less safe you become.
The deeper you go the less oxygen you can use in your mix.? If you stay within the safe maximum operating depth, then diving with nitrox is safer than with air.
An added-safety mix such as nitrox 32 could easily become the breathing gas of leisure divers in the future - even if they never get to realise it. Technical divers are the ones who understand the full implications of Nitrox.
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Trimix Divers
With the additional training courses, equipment and mixed gas it is normal that technical divers dive deeper than non technical divers.
Do I hear how deep is deep?
Worldwide, PADI-trained divers limit themselves to 18m. PADI puts a limit of 40m on recreational diving, and that is for those with a deep-diving speciality badge
The British Sub Aqua Club (BSAC) of which Newry and Mourne Sub Aqua Club are affiliated to, recommends a 50m ultimate limit. Beyond 66 meters, when diving on air, the oxygen content or fraction of oxygen in the air becomes 7 times greater than at the surface. This causes the oxygen to become toxic. This may cause a convulsion and at this depth this could become dangerousSome divers advocate deep air dives and I know a small minority who have perfected the art.
There are a small number of divers who venture beyond 66 meters on a regular basis. To escape the narcotic effect of the depth they use a mixture of oxygen, nitrogen and helium. This cocktail is known as trimix.
Heliox is what professional divers use. This is a mixture of just helium and oxygen with no nitrogen. Subsequently heliox is more expensive than trimix.
Another mix that is available is heliair. This is a trimix conveniently made by adding helium to air (oxygen and nitrogen, which stay in proportion).
These divers who use helium need to mix their gases and plan their dives meticulously, using calculations and then verifying these calculations with a computer and specifically designed software. Their diving is complicated because they often switch to different mixes of breathing gases both during the decent and the accent of the gas. The world record for an open circuit recreational wreck dive was recorded on 11.12.06 at a depth of 210 meters. The current word record for a open circuit recreational deep dive currently stands at 340 mtrs. During a trimix dive the diver may use as many as four or five different breathing gases.
Switching to the wrong gas mix could be fatal, so this requires meticulous discipline.
Helium reduces the effects of nitrogen narcosis at the extreme depths to which these guys go, but it adds in the complication of additional deco-stop time needed. Trimix is used in conjunction with staged decompression techniques. (When returning to the surface, stopping at different depth for periods to off gas and subsequently preventing a bend.
Newry & Mourne Sub Aqua Club has currently a Technical Team of 8 Trimix trained divers. These highly trained individuals have the necessary skills to conduct dives to depths of 100 meters and safetly return to the surface.
