Guest Writer: Butch Zemar
Many experienced scuba divers eventually want to go deeper, and maybe even technical diving. Deep diving has so much to explore. There is a constant debate on what gas to use for some technical dives. Some will say deep air is unsafe. Others say the cost of the helium for trimix does not justify the slightly added risk. Who is correct?
By adding Helium to an air or nitrox mix decreases the amount of nitrogen in the gas. Therefore, less narcosis and decompression sickness (DCS) risk.
Helium is expensive for most divers. You could pay as much as $200, or more, to fill a set of doubles. This is something hard to sleep on for some divers. Diving has not been only a rich man's sport. Many of the original pioneers were average wage earners.
Trimix adds a safety margin to diving deep that is worth considering. Experience divers can figure out the narcosis level where they are the most comfortable at depth. With gas mixing software, they can mix a tank to get the helium/oxygen/nitrogen mix to meet this level. They call this the Equivalent Narcotic Depth (END).
For example, you're most comfortable with the narcosis level from nitrogen at 80'. You are planning a dive to 180'. You can blend a trimix mix to have the similar narcosis feeling from nitrogen if you were at 80 feet while at the depth of 180'. Nitrogen narcosis and decompression sickness (DCS) risk factors are greatly reduced. This definitely makes the dive safer and more enjoyable.
Why would someone not want to dive trimix? This is a very good question.
- The cost of helium could prohibit people from diving deeper. There is so much to be explored by every diver.
- Logistically, some local environments do not reach depths that become risky where trimix becomes a requirement.
- With experienced divers, the added risk is marginal and is calculated. Honing your skills makes deep air diving tolerable and safe.
For example, Midwest shipwreck divers have to bring a shovel with them to get to 100', or in some cases 130'. The dive profiles for these depths are more of a multi-level dive. Unless someone is on a project of some type, they are not consistently at the maximum depth, working hard, for any extended period of time. There are exceptions to the rule, here. I'm just speaking in general terms that it is a non-issue.
Most technical divers always practice and hone their skills to be better and sharper as a diver. Deep dives require practice to become proficient. The more you practice, the easier deep diving will become.
Using any gas as a technical diver is just a tool in the toolbox.
In order to build a house, you will need a hammer. Picking a hammer to use will be determined by the task at hand. Through preparation, logistics and experience, you can figure out which hammer to use for the job.
Technical diving is no different. There is nothing wrong with diving deep on air. This is if you do the required preparation, logistics and have the required experience. Deep air is just another tool in the toolbox.
Article by: Butch Zemar
Butch Zemar "Scuba Butch" is a scuba instructor that has been diving for over 20 years with well over 2,000 dives. He teaches entry level divers as well as instructors at a heated pool in Chicago. Trainers from around the nation come to train in Chicago, so why not train with the best? "Scuba is a romance and entertainment business. We increase communication and relationships through the enjoyment of recreational activities. Visit http://www.ScubaButch.com
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