Tech diving is gaining popularity. We were so excited to see it here at Girls that ScubaHQ! There were a lot of questions, and we were nervous so we headed to Theresia Geller, a Blue Marlin instructor in Gili T. Lombok. She taught us the basics of twin sets and introduced us to technical diving. Here's what she taught:
Divers must maintain a minimum level fitness and health. Some conditions such as chronic illness, recent surgery or medication may make it necessary to obtain written permission before you can dive.
Academics - A technical course's academic portion is very similar to other scuba classes. Students will be required to do self-study and share their new knowledge with their instructor. Although the dive planning requirements for technical courses are more complex than what most people are used to, they are essential in executing a successful dive. The gas management portion of the planning discussion for overhead and decompression diving will take more time than most divers are used. A computer program is used to calculate the gas volumes and reserve required for each dive.
Different depths require the use of different gas mixes. The maximum partial pressure of oxygen a diver wants to dive at is 1.4 which is reached on air at 56m. Due to the water pressure the pressure of each individual gas increases and therefore we need to use appropriate mixes if we choose to go deeper. In general, the more oxygen a gas mix has the less deep we can go. A tech diver will use low oxygen mixes at depth and high oxygen mixes coming up shallower to off-gas Nitrogen faster and decrease the mandatory decompression time overall.
Make sure you understand what you're buying: Prices include instruction as well as eLearning fees. Remember that eLearning fees can run anywhere from $140 - $280. For example, a $640 course offered by us may be equivalent to a $500 course provided you pay separately for elearning.
Consider continuing on to Tec Sidemount Diver course in which you’ll learn additional skills specific to tec diving in sidemount, such as staging and switching deco cylinders.
Sidemount and technical were my first courses. Sidemount diving involves placing your tanks in your hands. I was so numb that my fingers and knuckles had been cut by the end. The idea is to take the tanks off of your hands and let them flow out in front. After making adjustments to the harness's size, the afternoon dive went much easier. I was now able to unclip the harness and 'Superman' with the tanks. Sidemount provides an amazing degree of freedom. Matt installed obstacle courses, and we soon found ourselves flying around them while holding tanks at our feet. We also tried barrel-rolling and swimming upside down.
Technical divers are able to explore wrecks and reefs at depths that are below the recreational limit of 30 m/130 ft. Specialized training allows them to explore underwater caves, and other places that are beyond the reach of recreational diving.
Sidemount cylinder mounting was originally developed for cave diving, and has become more common in technical diving. The sidemount cylinder mounting allows you to separate the dual cylinders with one stage per cylinder and mount them on either the left or right side of your body. Although this doesn't allow for the diver to breath from any cylinder in the case of a regulator malfunction, it does make it easier to access valves. Sidemount diving allows the diver to have a wider horizontal profile but a narrower vertical one.
Sidemount diving originates in cave diving and has since made its way into recreational, non-overhead dives. Simply put, you'll wear your tanks on the side of your body instead of one or two tanks strapped to your back. The tanks attach to the Sidemount BCD with clips and/or long bungee strings, giving you great flexibility. This flexibility allowed cave divers to get their tanks off the surface to make it fit through narrow spaces.
Your Sidemount BCD harness is made up of a bladder, sliding D-rings and bungee cords. Your tank position and trim will depend on their fit. Your instructor may spend a lot of time getting them right.
Cave passages that have been formed through millions of years of erosion are only available to those who are certified in overhead diving. They stretch thousands upon thousands of feet. The incredible time span in which these caves were created is a testament to their unique beauty and tranquility.
Backmounted doubles came into use in part because of the problems with backmounted independents and single orifice doubles, neither of which are as common in modern diving. Independents are two cylinders strapped to one’s back with independent regulators on each one. If a 1st stage was to fail the diver was down to one cylinder. Single orifice doubles were two cylinders linked together with a valve, and one 1st stage regulator. If a first stage failed on a single orifice doubles set all the gas would be lost. The isolated manifold doubles used today eliminate both of those problems. Each cylinder can be worked independently, but the diver can also breathe gas from both cylinders out of one regulator. This form of doubles is typically held together with metal bands and the valves are linked with an isolation manifold, allowing the two to be separate if needed. Backmounted doubles diving is similar to regular single cylinder backmount, offering a profile that is vertically the same.
Sidemount Diver Specialty dives may count toward Advanced Open Water Diver certification. Ask an instructor.
from 170 to 350 feet
While conventional scuba diving has a recommended maximum depth of 130 feet, technical divers may work at depths ranging from 170 feet to 350 feet, and sometimes even deeper.
The depth range of oxygen rebreathers (simple closed circuit) is limited to approximately 6 m, beyond which the risk of acute oxygen toxicity rises to unacceptable levels very quickly.
To begin a technical diving course, you must have completed the following prerequisites: a PADI Advanced Open Water Diver certificate or equivalent, a PADI Enriched Air Diver certificate or equivalent, and a PADI Deep Diver certificate or proof of at least 10 dives to 30 metres/100 feet.