© 2011 Steven M. Barsky. All rights reserved.
There are many famous people in diving who have developed marvelous inventions that have changed the way we dive. However, unless you are interested in diving history, you probably haven’t heard of most of them, except perhaps for Jacques Cousteau, who is widely reported as the inventor of the AquaLung®, but that’s another story….
The Edge Dive Computer was the first commercially successful dive computer that was based on microprocessor technology. It used a decompression algorithm, rather than tables.
For most divers today, one person who helped change the way we dive is a guy by the name of Karl Huggins, who saw the future of decompression theory and helped develop the Edge, the first modern commercially successful microprocessor-based electronic dive computer. Without the development of the Edge, we might all still be using paper based decompression tables to compute our dive times. Huggins today runs the University of Southern California’s Catalina Hyperbaric Chamber on Catalina Island, a long way from his home state of Michigan. He first became captivated with the underwater world watching the Cousteau specials on television and seeing the undulating beauty of a Red Sea nudibranch, the “Spanish Dancer” in an eighth grade science course.
Huggins Learns to Dive
Karl remembers receiving a pair of Jet Fins in junior high and being amazed at their speed and power, when he unexpectedly ran into the side of the pool. He loved the water and took courses in lifeguarding. In high school, he, along with other lifeguards, found a full-face mask and compressor and tried it out cleaning the bottom of the pool, but as he puts it, “There weren’t many opportunities in the area for a person to learn to dive at that time.”
But, it was his involvement in the attempted resuscitation of a man who had a massive coronary in Karl’s high school pool that left an indelible mark on Karl’s psyche. Although Karl and the others who made the rescue did their best, the man could not be revived. His memories of this rescue and the concern for others instilled into him by his parents were markers that changed his life.
For college, Karl enrolled in the University of Michigan in biological oceanography and took courses in aquatic leadership. Following an introductory orientation to the use of scuba, Karl enrolled in a scuba course in 1976 under the tutelage of Dr. Lee Somers, a legendary educator in the diving field. He went on to take further courses in underwater technology and chamber operations from Somers, and began to assist with scuba classes.
While taking the underwater technology course, Karl got interested in the concept of decompression tables and how they were calculated. Encouraged by Somers, who gave him several papers on decompression theory by Dr. Bruce Bassett, a diving physiologist, Karl spent his afternoons at the local bookstore, programming their HP67 calculator to run decompression tables.
As Karl admits, “I used the display calculator in the store, because I couldn’t afford to buy my own $700.00 calculator at that time. Using Bassett’s ideas and the U.S. Navy diving medical officer’s handbook, I just started playing with decompression calculations.”
When his father got a new calculator he gave Karl his HP55 calculator which could be programmed to do dive tables. Although it was less powerful, and had no print-out capability, it did the job.
In 1979, Karl took a trip with the other scuba class assistants and instructors from the University of Michigan to San Salvador, in the Bahamas. While on this trip, he met diving instructor Dee Scarr, who introduced him to the concept of multi-level diving, similar to a practice widely used in the commercial diving field known as “repet-ups.”
At that time, divers were trained to perform calculations for “square profile” dives, where, no matter what your profile was, you computed your whole dive as if it took place at the deepest depth you explored. This procedure “penalized” the diver for the maximum depth he reached. Scarr and other people, however, were using paper-based U.S. Navy decompression tables to calculate and perform extended dives by working their way “up” through the no-decompression tables to progressively shallower depths.
Just as a modern dive computer will allow you to make a multi-level dive for a longer time than what you could spend at your maximum depth, a similar profile could be calculated using the tables. With their method, you could extend your bottom time and calculate what’s known as a “repetitive group” while theoretically taking into account the additional nitrogen you absorbed as you stopped at different depths as you worked your way to the surface.
The concept of a multi-level dive intrigued Karl, but there were things that bothered him about it. Specifically, the Navy tables were based on six different theoretical tissue groups (compartments), while the calculations for repetitive groups were only based on one compartment. (For simplicity, you can think of a compartment like a particular type of body tissue, although it does not represent any specific tissue in the body).
When Karl returned to the states, he began running various dive profiles on his HP calculator to see what was happening mathematically in the other five compartments of the US Navy model. Based on his calculations, he found that in some cases using the multi-level dive procedure, you violated the Navy model, which could place you at higher risk for decompression sickness.
In his reading on decompression theory, Karl was given the work of Dr. Merrill Spencer, who had used a “Doppler meter” to detect bubbles in the bloodstream of divers, even those without decompression sickness. Karl began working on various ideas on how to put together a no-decompression table that would not cause the violations he found in the Navy tables when they were used for multi-level diving. Eventually, he developed a table with repetitive group designators that represented all six compartments.
Based upon Spencer’s Doppler limits and the work of Bassett, Karl developed a set of tables that was published by the University of Michigan’s Sea Grant program. The publication was entitled “New No-Decompression Tables Based on No-Decompression Limited Determined by Doppler Ultrasonic Bubble Detection.” (You can still download the paper off the Internet.) After graduating cum laude with his bachelor’s degree in 1979, Karl took a year off before starting graduate school in bioengineering. During that year Karl went through scuba instructor training at the University of Michigan with Dr. Somers and got to know Dan Orr (now president of DAN) who, at the time was running the scuba program at Wright State University in Ohio.
Going Over the Edge
Huggins first publication on decompression tables was, "New No-Decompression Tables Based on No-Decompression Limits Determined by Ultrasonic Bubble Detection."