If you dive in contaminated water, and most public safety divers will, then you must be aware of the procedures to be followed for decontamination, i.e., the cleaning of the diver and his gear following a dive.
Of all the diving performed by professional and commercial divers, black water diving has to be the most challenging on a purely psychological basis.
Dive team members should be equipped with the right protection for cold water diving. In most circumstances, this would include a dry suit with insulating undergarments, dry gloves, a dry hood, and a full-face mask.
In the real world of public safety diving, there is no single definition of what constitutes “cold water.” Defining cold water is difficult because it depends on so many factors, i.e., the water temperature, the diver’s size, amount of subcutaneous fat, state of acclimatization to cold water, individual physiology, and activity level. What one person perceives as a comfortable water temperature may be intolerable to another.
The real issue here is at what point does exposure to cold water become debilitating? For the moment, we’re assuming we’re talking about a diver who either is wearing inadequate thermal protection, or whose thermal protection has been compromised, i.e. a flooded dry suit. There is a continuum of responses to cold water that runs the gamut from mild discomfort all the way to unconsciousness and death. As far as I am concerned, the line is drawn at “debilitating effects” because once the diver cannot perform at the peak of his ability, the risks in diving increase to unacceptable levels.
Debilitating effects range from loss of concentration to shivering and the inability to use one’s hands properly. Any of these situations puts the diver at elevated risk and indicate that the diver is not wearing adequate thermal protection for the task at hand. If you notice these signs in yourself or another diver, it’s time to terminate the dive and regroup.
When divers discuss diving in cold water, the term “hypothermia” frequently comes up. Although we all think we know what we mean when we discuss the issue of hypothermia, the reality is that physiologists have a very different perspective on hypothermia than most divers. For a physiologist, hypothermia is defined as a body core temperature below 95 degrees F. Above this temperature, while you might be uncomfortably cold, by definition, you are not hypothermic.
Dr. Neal Pollock, Ph.D., Research Director for Divers Alert Network (DAN), points out that, “The threshold core temperature for hypothermia is 35C (95F), a substantial drop. It is unlikely that a diver with even modest protective garments will reach that point. There is a big gulf between being cold and being hypothermic. Shivering (episodic or continuous) and general impairment will develop long before the definition of hypothermia is met. I think that the focus on the structure of hypothermia stages (mild, moderate and severe) is unhelpful, confusing cold impairment with hypothermia. You do not need both for serious problems to develop.”
Dr. Pollock knows that of which he speaks, and has experienced a flooded dry suit during a polar dive on a 43 minute excursion in 29 degree F seawater. Since he was wearing Thinsulate® under his dry suit during the dive, he was able to continue the dive, which was being conducted to measure his core temperature (don’t try this at home!). The only reason he continued the dive was that it was being conducted for the express purpose of measuring core temperature, otherwise this type of occurrence would normally call for the dive to be aborted. Interestingly enough, the largest drop in Dr. Pollock’s core temperature took place after he exited the water.
True hypothermia is a very serious condition and can lead to unconsciousness, cardiac arrhythmias (irregular beat), and death. Clearly, these are scenarios that you don’t want to occur underwater.
As mentioned earlier, you don’t have to be hypothermic to place yourself at risk in cold water. A dry suit (with insulating undergarments) alone is not adequate thermal protection in cold water. Proper protection of the head and hands is equally important, and dry hoods, full-face masks, and dry gloves are vital, especially for diving under the ice. One issue that may occur with dry gloves and dry hoods are that if they are compromised, their insulation value will be lost. Keep in mind that every piece of equipment has its own advantages and disadvantages.
The language you use as a public safety diver is important, since your actions may be scrutinized and challenged in a court of law. In most cases, you will not be able to properly diagnose a dive team member as hypothermic, unless you are using some very sophisticated equipment. In any situation where you must describe a diver’s inability to perform in cold water, it’s best to say that he suffered from “cold stress.” Leave the medical diagnosis to the physiologists and physicians.
About the author:
Steven M. Barsky is a professional diver, diving consultant and author. He has written 18 diving texts and and produced 9 diving DVDs. His latest DVD video, Careers in Diving, was released in December 2013.
photo by Steven Barsky. Surface-supplied diving gear is a good way to go when diving in polluted water. All communications with surface-supplied gear are normally hard-wire. Here, FBI Dive Team members train in body recovery in San Pedro, California.
If there is one thing that is essential to working effectively underwater, it’s teamwork. And, to work as a cohesive unit, everyone in your team must effectively communicate, both topside and underwater. While you can get by with hand signals for ordinary recreational diving, for any type of professional diving, verbal communications are vital to teamwork. The proper use of communications technology, and the content of what you say and how you say it, are distinguishing characteristics that separate the amateur public safety dive teams from the professionals. We could write a book on this topic, but we’ll attempt to summarize some of the most important points here.
The two types of electronic communications for diving are wireless and hard wire systems. If you are using conventional scuba gear, you can use wireless with a tether or a tether that has integrated communications wiring. Even if you use wireless communications, the use of a tether is essential for safety reasons. Without a tether, it can be impossible for your teammates to find you should you become unconscious and stop breathing while you are underwater.
Divers using surface-supplied gear will, of course, have a communications wire built into their umbilical. Using surface-supplied gear with a diving helmet rather than a full-face mask will give you the best communications and provide the highest degree of safety. Surface-supplied gear is always preferred for diving in polluted water whenever contaminants can have long-term negative health effects, or cause serious injury or death.
To have good communications on a dive team requires a leader who sets an example by communicating effectively and encourages team members to speak up when they have a concern. In my experience in dealing with commercial, scientific, and public safety divers I’ve always observed that most people are hesitant to speak up about safety issues until another individual voices a concern. Following the identification of a safety issue, other team members will frequently thank the individual who spoke up for identifying a problem that they noticed but were afraid to call to anyone’s attention. On the best dive teams, this should not happen.
How you say things is also very important. If you’re a team leader, you can make or break the people on your team through careless remarks, especially thoughtless criticism. A team leader needs to be firm, but fair and consistent. Encourage your people and work to bring out the best in each diver.
Following good protocols is essential for good communications with divers who are working underwater. Probably the single most important skill for the dive supervisor, or whoever is running the dive, is to develop good listening skills. Learn to listen to what the diver is saying, how he says it, and his breathing. By following this procedure you will have more and better insights into what the diver is doing and how he is coping with the stress of the dive.
More importantly, as the dive supervisor running the topside communications, avoid the temptation to enter into idle chatter with the diver. Keep your side of the conversation brief. Avoid talking over the diver. This is especially important if you are using a two-wire communication system where topside over-rides the diver’s speech. Listen more than you talk. Keep your communications short, i.e., 15-20 seconds, and wait for the diver to respond. Never drone on and on for any extended period of time.
As a diver, it’s important to let topside know where you are at all times as well as to keep them informed as to what you’re doing. Always be honest about what actions you are taking and what progress you have made on the job at hand.
Both the diver and topside need to be explicit as possible when giving or responding to directions. As a diver, if you want the tender to take up the slack in your tether or umbilical, tell them how much slack you want them to take up as well as how fast you want them to take it up. As a supervisor running a dive, you must be sure to keep track of the diver’s bottom time and ensure that they get off the bottom with a margin of safety. If your policy is to not run decompression dives, then allow enough time for the diver to get clear of the bottom and make his safety stop without running up against the no-decompression limits.
You can have the best wireless communication or hard-wire system, but if you don’t use it properly, you’re wasting a valuable asset. Safety must always come first for the public safety diver and communications are a vital component of safety.
About the author
Steven M. Barsky is the author of the book, Diving in High-Risk Environments. He has worked extensively with public safety dive teams, and has experience in sport, scientific, and commercial diving. For more information, contact Steve through his website at www.hammerheadpress.com.
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