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Technical Diving

Jimi Mayes   Mar 08, 2021

Not Your Everyday Dive.

Intrigued by the shipwrecks of the Great Lakes and despite being raised in Chicago, I was unaware of the plethora of sunken vessels just off our shores. It would be a couple of years before I could put together a dive trip to the Great Lakes.  After traveling to Alpena, Michigan and after diving on Oscar T. Flint, Grecian, E.B. Allen and Montana, I was hooked and immediately began dreaming of my next adventure as a Great Lakes Diver.

That began my journey into technical diving. A journey that I have thoroughly enjoyed. It has required many hours of classroom time, a tremendous amount of time underwater. It has introduced me to some of the best divers associated with the discipline of technical diving in the world. Tec diving was a natural progression for me as the majority of intact wrecks of the Great Lakes are deeper than 130 feet. Although many fantastic wrecks including the Thomas Hume are located well with-in recreational depths. I desired to stay longer and explore these wrecks in greater detail that is not allowable recreationally. I also quickly discovered technical diving dovetailed very closely to my professional career of planning and mission execution.

What the Heck is Technical Diving

What is technical diving? There is a lot of discussion of what is technical diving. I will use the definition as set forth by NOAA which defines technical diving as "all diving methods that exceed the limits imposed on depth and/or immersion time for recreational scuba diving. Technical diving often involves the use of special gas mixtures (other than compressed air) for breathing. The type of gas mixture used is determined either by the maximum depth planned for the dive, or by the length of time that the diver intends to spend underwater. While the recommended maximum depth for conventional scuba diving is 130 ft, technical divers may work in the range of 170 ft to 350 ft, sometimes even deeper. Technical diving almost always requires one or more mandatory decompression 'stops' upon ascent, during which the diver may change breathing gas mixes at least once."

Let's Step Back In History

It is difficult to determine when technical diving began, we do know many of the techniques and procedures originated from cave diving. Cave diving became a recognized type of specialty diving in the 1980s. With the publication of Aqua Corps by Michael Menduno, in the 1990s. Names of pioneers participating in technical diving such as Billy Deans, Bret Gilliam, Tom Mount, and Jarrod Jablonsky started to appear on the dive scene. Since that time almost all training agencies have instituted technical diving programs. I wish to make a point here, simply buying a technical style BCD or diving beyond the maximum recreational depth of 130’, does not make one a technical diver. Neither does a diver using technical diving techniques without proper training.

Time For New Toys

Technical diving requires and demands a great deal of equipment well beyond the recreational diving configuration. When it comes to equipment tech divers practice the rule of “three is two two is one and one is none”. A technical diver may choose back-mounted double tanks or opt for a side-mount twin cylinder configuration. As the technical diver progresses they will move from a single decompression cylinder to using multiple decompression cylinders. Technical divers will also need a minimum of two regulators and up to 5-6 regulators for the trimix diver. Dry suits and bladder BCDs, two masks, two computers, three cutting devices, a lift bag or surface marker buoy (SMB), three lights, 2-3 reels and other redundant equipment.

The Winner Is...  Training

Most training agencies follow similar training protocols. There are different levels/sub-divisions of training, (usually three) class titles may differ, but they generally adhere to depths, bottom times, breathing gasses, decompression gasses and limited deco times.

The first level of training teaches the diver to stay with-in recreational depths but provides the skills to stay longer at depth and decompress using a single deco tank (generally 50% EANx blend) on a back gas deco schedule. The next course will train the diver to dive deeper (145’-150’) and allow them to have a longer bottom time. Here they will practice accelerated decompression and use EANx blends up to 100%. The third class will train the diver to dive to depths (usually to 165’) for extended times decompressing utilizing two deco gasses. (most likely 50% and anywhere from 80%-100%). For those divers who want to dive deeper, Trimix (a mixture of helium. nitrogen and oxygen) becomes the next step.

Before the diver gets to open water certification (most agencies require 4 dives per course for a total of 10-12 dives), they must master the theory of decompression, become knowledgeable in dive physics and physiology. They will learn to “hand jam” dive plans using formulas and become familiar with Dive Planning Software (DPS). They will plan the dive and then develop contingency dive plans to adjust for unforeseen circumstances that occur during the dive.

Once the diver proceeds to the pool/confined water they will learn to deploy lift bags or SMBs. Practice out-of-gas procedures. Learn to overcome any number of emergencies all of which are designed so the diver is 100% self-sufficient. Technical divers must solve emergencies underwater as swimming to the surface is not an option due to decompression obligations. New finning techniques will be developed. The tec diver will practice gas switch drills to accelerate their decompression time. As the diver continues with their education they will go more in-depth about Central Nervous System (CNS) Toxicity, Pulmonary Toxicity, and more decompression theory.

Let me also say that the technical diver may do everything correct but due to the hazardous nature of technical diving, the diver has an increased risk of injury.

Discipline, Mindset and Fitness

Tec diving demands discipline, the diver must adhere to the decompression schedule. There are no short-cuts. It requires a mindset and commitment to training and continued education. Again, there are no shortcuts. Technical divers plan their dives as a team and dive as team. If a diver is a Lone Ranger type, they may not want to participate in tec diving. The tec diver must possess a degree of fitness not only to lessen the possibility of decompression sickness, but they must climb back on the boat with quite possibly 4 or more tanks strapped to them.

We also adhere to the adage; “Plan Your Dive, Dive Your Plan but expect the unexpected” Remember “Murphy” is always lurking.

For the diver that is willing to put forth the effort, time, and expense, technical diving provides the diver with a tool in their toolbox to explore of our beautiful underwater world.

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