Diving in Extreme Weather

by Sean Harrison:
##Emergency Response Diving International, ERDI, is always traveling around the world learning from public safety divers in the field. During our visits, it is interesting to see how various teams prepare for seasonal changes within their region. These changes can range from extreme to minimal. In the North American regionsthis time of year, the preparations generally focus on extreme cold and ice, whereas the southern regions focus on heavy rains and flooding. In both regions however,preparation is needed.

Teams have a wide variety of training environments at their disposal; from pool facilities to lakes, ponds, and even oceans. To simulate ice training, teams will cover one corner of a pool with a thick piece of plastic that has a hole cut into it, just like the hole that would be cut in real ice. The rest of the pool is covered in a thin sheet of plastic to simulate an overhead and darker environment. This allows the team to practice for winter calls before the first snowflake of the season falls. All the same protocols are followed including: line pulls and communications, harnesses, tie-offs, and surface support. There are even teams that have cars completely cleaned and equipped with lexan windows submerged for training. When punched, the window will drop as if the glass has been broken. They will use manikins of all shapes and sizes to simulate whatever the team may encounter, and seatbelt webbing so divers can practice cutting and freeing victims. While this is not exactly like diving on and under the ice, it works as a great refresher and gets a team thinking of all the required steps and protocols for working in these conditions.ice hole As with colder water and environmental changes, public safety responders must take into account the physiological changes too, for example, dexterity of finger movements which would decrease in these conditions. Preparing for entanglements is a necessity as first reponders must be able to free themselves in case of an entanglement. Wearing the proper personal protective equipment (PPE) as a diver, as well as tender support. Making sure to use ice rescue suits for static water conditions, as they are not intended for moving water applications.

Teams in areas where floods are expected, train for two different types of exercises: flooded homes and cars, as well as swift water. Training for stagnant flood water varies depending on location and team structure. Generally, it consists of how the team should be properly equipped, in regard to contaminated water,search patterns, and marking protocols. For areas where swift water is an issue, teams go through exercises of knot tying, finding anchor points, ropes and high lines, load bearing calculations and when not to deploy personnel into the water.

This extreme weather training, along with routine training ensures the best possible outcome for the victims, along with helping to insure the entire team comes home safe. While these extreme weather scenarios cannot be re-created for training purposes, when the time comes, these teams will be better prepared than if they had not trained at all. The hopes are that prior to an actual call-out, the team will get a chance to practice on the ice or in swift water. Unfortunately, this is not always the case. Early season ice draws unknowing victims and flash floods come without warning, hence the name. A necessary point that needs to be stressed is: every department/agency must have a solid documented SOP and SOG. This not only protects the rescuer, but also the department.

Teams all across this nation and the world provide an excellent service to the community and ERDI hopes to be able to visit as many as we can, and highlight their efforts. If you have a story about your team working in extreme weather conditions, please send it in along with any supporting photographs.

Hypothermia: It’s All a Matter of Degrees

Full face mask diver in drysuit

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.