Today’s op however, is the type of call every responder dreads. Seven days ago, the five year old son of a prominent citizen disappeared while riding his bike around the neighborhood. Until today, there had been no clues as to his whereabouts.
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.
By Mark Powell
The image that many technical divers try to promote is that they are tough, macho divers. The shaved heads and stubble, combined with equipment that would make a Special Forces diver look inadequate, all add to this image. The message is that they can leap tall buildings in a single bound and endure conditions that no mere mortal could withstand. However the truth is a little different. In fact many technical divers spend as much time thinking about how to stay warm during their dives as they do planning the dive itself. The reason for this is that technical dives are more challenging than many recreational dives. They are typically deeper, longer, and colder. The intelligent technical diver recognises this and tries to protect against the cold wherever possible.
One of the main concerns of any technical diver is warmth, both from a comfort and a safety point of view. In general the deeper we go the colder it gets. A few years ago I was teaching an Advanced Trimix course in Turkey and between the surface and 80m there was a difference in temperature of 10 degrees. This meant that while we might have been comfortable on the surface you would get very cold at depth. Gloves intended to keep my hands warm at depth were uncomfortably warm during the decompression. A more common problem is that technical dives tend to be much longer than recreational dives and will usually involve long decompression stops. Even if there is no difference in temperature during the ascent it is common to get colder during the decompression. I don’t normally get too cold during the main part of the dive due to choosing the right undersuit, swimming around and the fact that my mind is occupied, but during decompression it is much more common for me to feel the cold. During long decompression stops you are not swimming around or moving to any great extent and your mind is not as occupied. It is during these long periods of mental and physical inactivity that I often feel the cold.
In addition to the comfort aspect of getting cold there are a number of very real safety issues involved. The cold can slow down your reaction speed and thought processes which, when combined with Narcosis can affect how quickly and effectively you react to problems. Cold hands can also quickly lose dexterity which can make it difficult to effectively handle equipment, operate computers, switch to decompression gas, etc.
Most importantly there is strong evidence that getting cold towards the end of a dive can increase the risk of decompression illness. During the early parts of the dive the diver is fairly warm and blood flows to all parts of the body. Nitrogen and Helium are carried by the blood flow to the whole body and the level of the inert gases dissolved in the body increases. Towards the end of the dive, during the ascent and decompression stops, the inert gas is normally carried by the blood back from all parts of the body to the lungs. However when we get cold one of the body’s reactions is to restrict blood blow to the extremities and concentrate it in the main core of the body in an effort to conserve heat. When the skin temperature starts to drop the body will reduce the circulation in your limbs, this is known as vasoconstriction. This has the effect of reducing the amount of blood flowing to the heavily inert gas-laden tissues in the extremities which in turn reduces the level at which Nitrogen and Helium off-gas from these extremities. In effect, being cold has slowed down the release of inert gas from these tissues. As a result the speed of off-gassing is slower than predicted and the excess Nitrogen and Helium in these tissues can cause decompression illness. Recent research has shown that this can cause a significant increase in the risk of decompression illness.
Due to the risk of decompression illness, suit floods and leaks are much more important to a technical diver. I know many sport divers whose suits regularly leak and for them it is merely an inconvenience however for a technical diver it can be a much more serious problem. Similarly a flooded suit can be cold, uncomfortable, inconvenient and irritating on a recreational dive but on a long decompression dive it can also be very dangerous. As the diver gets cold their decompression become less efficient. This means that at the very time they want to get out of the water they need to stay longer to make up for the inefficient decompression. Here it is a balancing act between the dangers of hypothermia and decompression sickness.
It is a combination of the comfort and the safety that makes technical divers so concerned about the particular design of undersuit they use. There are a range of undersuits that use different materials to keep the diver warm. In addition to keeping the body warm it is vital to keep your hands warm. As we have seen cold hands can cause problems with dexterity making it much more difficult to carry out certain tasks. For this reason a technical diver will also think long and hard about their choice of gloves for long cold dives. One option is to simply wear thicker gloves. The extra thickness helps provide better insulation for the fingers although the thickness of the gloves also results in reduced dexterity. The same problems apply with 3 finger mitts. These mitts have one compartment for the thumb, one for the index finger and a third compartment which contains the remaining three fingers. Having the three fingers together helps to keep them warm although the thumb and index finger get just as cold as in standard gloves. In addition having the three fingers together significantly reduced dexterity for some tasks and can make some standard hand signals difficult if not impossible. Again there is a trade off between warmth and dexterity. By getting cold we can lose dexterity but many of the gloves designed to keep our hands warm have the side effect of reducing our dexterity anyway!
Another option is dry gloves. These are gloves that are fully sealed against the drysuit and allow no water into the glove. In some designs the glove is linked directly to the airspace of the drysuit. This removes any problems with equalising the two air spaces but has the risk that a punctured glove can cause a complete suit flood. Other designs have a standard seal on the dry suit so that the dry gloves are a separate air space. In this case some mechanism is required to allow equalisation of the air space in the gloves so that the diver doesn’t get uncomfortable squeeze on their hands on the way down or excessive expansion of air in the gloves on the ascent.
The typical image of a technical diver is some macho tough guy however, as we have seen, the reality is that technical divers are more concerned about keeping warm and comfortable than most other divers because the consequences of getting cold can be far more serious on a decompression dive than on a recreational no-stop dive.
by Mark Powell
As I write this article, I am comfortably sitting in my office in sunny South Florida. The weather is quite fair, around 75 degrees with a light wind, a few harmless clouds but mostly sunny. The water temperature recently has been in the mid to high 70F degree range; I consider a 5mm wetsuit to be adequate for my ventures. Diving other parts of the nation in mid February will have far different and most certainly more extreme conditions though, involving the much more technical aspects of scuba diving.
Freezing temperatures, blankets of snow, frozen water, and wind chill factors require a different type of dive plan. When I think of this type of training and diving (ice, rescue and technical training) the first name that comes to mind is Hank Woronka and all the guys over at Lake County Diver Supply out of Hobart, Indiana. Hank has been diving for over 50 years and ice diving in particular for over 34 years. When I had questions concerning diving these extreme environments, Hank would be the gentleman to answer them. I had the pleasure of speaking with him recently and inquire about some of the equipment requirements, planning, and execution for such intense diving and rescue training.
Of course, a great deal of training and education is required before attempting any sort of cold water dive and especially ice penetration, thermal conditions and over-head environments could pose a great threat to those inexperienced. This article will simply touch on some of the basics and techniques shared with me. Special considerations for equipment are a crucial topic when dealing with extreme climates. Exposure suits, full face masks, and thermal gear are all of course vital instruments to take into consideration. Every piece of equipment must be designed with special regard when the surrounding environment is at literally freezing temperatures. In particular, first stages, regulators, primaries, secondaries, inflation hoses, gauges etc. must be able to withstand freezing temperatures to prevent malfunction.
Training for buoyancy control, harness, weights and ropes, communication techniques and equipment malfunction or freezing is also advised when diving and especially in the mentioned environments. Ice conditions are also a critical variable: ice forms, depth of ice, and site preparation all account for performing a successful operation. When cutting (with the use of an ice saw or chain saw) into the ice when deemed acceptable conditions, a 6x6ft triangle is cut to allow easier entry and extraction from the ice hole. The closer angles of a triangle shape allow the diver greater capability hoisting him or herself (with help from the tender) out of the ice hole and onto the solid ice surface. Every aspect of diving must be scrutinized and carefully adjusted for these sub-zero conditions, there is truly little to no room for error. The effort and training for ice diving is truly astonishing.
Hank recounted from over the years countless victims, cars, and evidence retrievals from frozen lakes and ponds. The importance of proper ice training is significant for everyone and everything involved. It has become a crucial aspect of scuba diving worldwide, whether it is for recreation or for rescue/recovery attempts. He mentioned in our conversation that ice diving and rescue/recovery is a huge process, one that consists of a well prepared and well trained team. Each member performing a task for the overall safety of everyone involved. Working as a team in this type of environment is essential for the overall success of the dives. Ice diving is a true test against the elements; success is accomplished by those who are willing to put the time and effort into learning such a technical aspect of the field.
By Steve Lewis
When I mentioned to a friend that I was writing a short article for TDI about diving under ice, she asked where I’d be writing about. She has known me long enough to have heard about “cold-water adventures” happening under pack ice around Baffin Island and Sirmilik National Park in Canada’s far north, iceberg diving off the Atlantic coast of Newfoundland, and ice-wreck diving during the long Great Lakes winters.
I told her the locale was far closer to home. “They asked me to write about the most fun I’ve had ice diving,” I told her. “SO, I’m going to write about diving in a small pond during Winter Carnival in the local village.”
She asked, why nothing about the amazing upside-down cathedral-like spires of sea ice that glow as top-side sunshine fractures into a thousand different shades of blue and sapphire? Why no mention of an ocean floor thick with sea anemones, sea stars, isopods, and a million different creatures living below a solid roof of ice? And wasn’t I going to mention catching glimpses of walrus and narwhales at depth, or the interaction of great seals checking you out and trying to chew strobe lights and dome ports off cameras? Oh, and no mention at all of polar bears “upstairs” playing cat and mouse with your surface support… them the cat, tough guys weighing in at 240 pounds relegated to the role of mice! Nope, none of that and nothing at all about diving on giant icebergs stuck fast in the sea floor 30 to 40 metres below the surface and offering the most spectacular swim-throughs imaginable.
Instead I wanted to explain why one of my favorite memories of ice diving took me to a three-metre deep muddy bottomed lake in the middle of rural Ontario during one of the coldest winters on record… almost as cold as the one we are suffering through right now.
But first, some explanations.
Diving under ice may sound odd especially if you are a diver who has only experienced coral reefs and blood-temperature water. Well, actually, it is a little odd no matter what your background. When diving requires a chain saw and steel pike to cut holes in the solid ice covering a lake, river or ocean, we are clearly not talking about run-of-the-mill scuba.
Ice diving is different. It requires specialized training, equipment that is not to be found in every dive shop, and surface support that must pay attention and take an active role during the dive.
However, ice diving is an attractive and uniquely exciting experience. Visibility under ice, whether in the Arctic or a local quarry, is typically excellent, and made more majestic by soft light filtering through layers of ice from the world above.
Ice diving covers many types of environments – the ocean, lakes big and small, even rivers and spots where ice floes may be present rather than solid ice. In marine environments especially, the aquatic life you encounter can be stunning. Often overlooked, cold-water diving can offer the very best subjects for photography and video. Visibility is often stunning too. Ice provides a protective layer so that wind does not whip up the surface (no seasickness!) and with water temperatures hovering between 0 and four degrees C, and low light levels, algae growth is inhibited.
Ice diving, just like cave diving and advanced wreck diving, is conducted in a true overhead environment, and it too requires special training. One critical thing to understand is that the techniques for cave, wreck and ice – while sharing some common concepts – are different enough that being proficient in one does not prepare you to dive in another. This is especially true of ice diving since not only is ice diving overhead environment diving, it is also carried out in extremely cold conditions that require special attention to issues that are not relevant when diving wrecks or caves.
An SDI ice diving course will teach you the safety aspects of diving while tethered on a rope under ice, but also how to cut the ice hole through which you enter the water, and how to tend safety ropes for other divers while you remain on the surface in a support role, AND how to prepare your regulators for performance under the ice.
Here are a few of the major differences. Generally speaking, safe ice diving requires a minimum of four people per dive: two divers operating as a buddy pair, and two people to tend their lines.
It is even better (read: it offers more security) to have at least one extra person geared up and on standby ready to get into the water in the case of an emergency. It is also standard practice for each diver to be tethered separately, and to have their own line tender, and is not recommended to have two divers attached to one line. Divers attach lines to a webbing harness with locking carabineers and a bowline knot, much the same as rock climbers.
KEEPING IN TOUCH
Being able to communicate with your line tender – the person attached to the other end of your tether line – is an important part of ice diving. Since you are diving in extremely challenging conditions, it is critically important that he or she knows you are doing fine throughout the dive, and if that is not that case, that you need help. During an ice diving course one learns about giving clear, non-ambiguous rope signals. You do not want someone to start hauling you in like a large trout when you are in the middle of getting that perfect nudibranch photograph.
Apart from the obvious dangers of diving in an overhead environment, ice divers must also be careful to monitor their core body temperature both beneath the surface and during surface intervals. Often, the coldest part of an ice dive is the time between dives! Repeat dives should only be undertaken when one is completely comfortable and fully warmed up. One surface-interval trick is to eat high-energy, hot food to replace one’s energy levels.
Ice diving requires special equipment. To begin with, one needs a regulator that will function correctly in extreme cold. This usually translates into an environmentally sealed regulator set, which is designed specifically to be less susceptible to freezing and resultant free-flow of gas.
As well as being environmentally sealed, ice divers also only breathe from their regs when submerged since water – even freezing cold water – may be actually warmer than the surrounding air… especially when the wind is blowing.
Most ice divers also carry some type of redundant gas source. This may take the form of a Y or H valve on a regular single cylinder, a set of twin tanks, two sidemounted tanks or a single cylinder with a pony or stage bottle.
And while some brave souls have been known to ice dive in wet suits, most opt for drysuits and warm underwear, a thick hood, and dry gloves. Even those on the surface tending lines need to be protected. Thick anoraks, caps that cover ears, non-slip, water-proof shoes, and decent gloves are standard. So too is some sort of wind-break or screen, and in really top-flight, well-organized, and deluxe expeditions, a warming hut that sits on top of the diving hole!
Actually, an SDI ice diving program will also introduce divers to gas management procedures, kit failure procedures, personal health and fitness issues and plenty more. It can be a challenging program, but really worthwhile because ice diving does present some unique opportunities to experience diving in a totally different light, as it were.
Which brings us to my story about my best ice dive, and as mentioned, it was not in some exotic locale, just the local village during Winter Carnival. One of the guys in a service club in the village was an ice diver and he suggested something a little different as a fundraiser. For a donation, kids would ice fish and catch numbered tags. Each tag won a small prize… a toy, a gift coupon, a cup of hot chocolate. Our job was to gather around the “fishing holes” wait for “hooks” to appear – actually the hooks were small clips similar to the ones on novelty key rings – and load them up with the tags… then give ‘em a tug.
The effect was priceless. The only issue we had was keeping up with demand. As soon as youngsters saw their friends landing “fish after fish” there was a lineup!
Great fun, great idea, and seeing the look on kids’ faces, priceless.
We posed the same questions to an ice diver and a tropical diver, here’s what we got…
1. How do you prep for a dive?
(ICE) First we have to check thickness of ice and make sure it is safe to walk on with our heavy equipment. We require ice that is at least 6 inches thick when teaching the SDI Ice Diver course. In Utah it is typically between 8 and 24 inches thick when we go diving. Besides getting all the gear ready you have to decide who will be surface support, line tender, and safety diver for each dive. Multiple sets of clothing are good since you normally get a little wet cutting the hole whether it is from water or sweat. A warming hut is nice for changing into your diving exposure protection rather than wearing it during all of the prep work prior to diving.
(TROPIC) First we check the weather and the tide charts to see if ocean conditions allow for diving. Depending on the location we’re diving, whether it’s a shore dive or a boat dive, will determine how we prepare for the dive. If it’s a shore dive, we’ll load our gear into a vehicle and drive to the site. If it’s a boat dive, we’ll put our gear on the boat and we will head out to the site that way. If necessary, sea sick medicine and sun screen should be considered, along with snacks for in between dives. You can usually dive in warm water in a swim suit, or rash guard and board shorts, if you tend to get a little cold you might need a 3mm wetsuit for 1-2 dives per day.
2. Equipment considerations for a dive
(ICE) Ice diving requires all of the standard equipment for scuba diving and more with some special considerations. It is helpful if the harness or BC has large D-rings so that you can securely attach the line to you and your buddy.
Because of the temperatures, a drysuit is required. Dry gloves and heated undergarments are recommended and make the dive much more enjoyable. Because of the cold temperatures most divers wear thick, or layer multiple, undergarments. This adds quite a bit of buoyancy so the diver must be sure he has enough weight and sufficient lift in his BC to counteract the additional weight.
The freezing temperatures also require the diver to ensure that the chosen regulator is tested and approved for use in freezing and sub-freezing temperatures. An environmentally sealed regulator is most often preferred due to first stage icing problems.
A great deal of additional equipment is required to cut the hole. An auger is used to cut 3 holes in the ice. Next a chainsaw is needed to cut between the holes making a triangle. If the ice is thicker than the length of your saw you may need to cut out blocks and remove them in pieces. Ice screws are used to secure diver lines to the surface and the divers. Snow shovels are used to shovel snow off in the shape of arrows pointing back to the exit so divers below can see them in an emergency.
Ice divers also need standard cold weather gear and safety equipment including a heated shelter and sleeping bag in case of hypothermia. Don’t forget some sleds to drag your gear out onto the ice.
(TROPIC) Diving in the tropics doesn’t change the fact that you will need all of the standard equipment for scuba diving. You might also consider a full length wetsuit or “skin” in the event you run across a jelly fish.
Even though the water temperature is usually around 26-30C / 80-86F after long in-water durations, getting cold can sneak up on you unexpectedly.
Depending on the location, if you are shore diving, towing a dive flag might be required to let passing boats know your location underwater. Carrying a Surface Marker Buoy (SMB) is highly recommended and often times required if you are diving off a boat to allow you to signal your location on the surface from a far distance if you get lost.
3. How long are your surface intervals and what do you do during your time out of the water?
(ICE) We concentrate on warming up and gearing up for the next dive while keeping the hole from freezing over. During training dives, we must balance the off-gassing during the surface interval with staying warm enough to complete a second dive.
(TROPIC) During our surface intervals we prepare our gear for the next dive, eat snacks, let the hot sun warm us up, and sometimes snorkel on the surface if conditions allow. We talk about what we saw on the previous dive, flip through fish identification books, and every now and then a pod of dolphins will pass by to really brighten up the time spent out of the water.
4. General Hazards
(ICE) The first hazard everyone thinks of is hypothermia. Any time you are exposed to freezing environments hypothermia is a concern. Staying warm is important and necessary for the diver’s safety. The diver’s thermal status will affect the rate of inert gas uptake and elimination, and rewarming before a repetitive dive is as important as accounting for residual nitrogen levels.
Any overhead environment can be a hazard. It is necessary to exit in the same place you entered. You can’t always just go straight up. Without a line, finding the hole you entered could be impossible.
More equipment means things are more complicated. The equipment can have more frequent problems such as free flowing regulators, icing over on the surface, etc.
(TROPIC) Because many tropical dive destinations can be fairly remote, make sure to have a first aid kit and oxygen on hand as emergency medical care might be delayed in the event of an accident. Staying hydrated is equally important in this hot humid environment which easily brings on dehydration. In addition, sun screen is usually a must to avoid a painful sun burn keeping you out of the water.
Diving in warm clear water brings on additional set of hazards often times overlooked… It’s important to pay close attention to your depth and time as it’s easy to end up deeper than you originally planned for. Keep an eye on your computer throughout all portions of the dive and if you’re not with a dive guide – make sure your navigation skills in check to ensure you end up back to where you started.
5. How long are you dives?
(ICE) During our ice diving courses, 25-35 minutes would be a typical dive. Bottom time may be limited more by a diver’s intolerance to cold than his exposure to increased oxygen partial pressures or the amount of decompression required.
(TROPIC) Dives in the warm water of the tropics is usually dependent on no-decompression limits or air consumption rates. If you’re doing a shallow reef dive in 6-12M / 20-40FT, you could easily spend over an hour underwater. Deeper dives in the 18-30M / 60-100FT are usually under an hour.
6. What do you see on your dives?
(ICE) Ice diving can be a serene and beautiful aspect of SCUBA diving. As a winter activity, ice diving offers the diver the opportunity to enjoy sport diving year round. In freshwater lakes, we can see everything we would on a normal dive, along with the beauty of the ice itself.
(TROPIC) Tropical diving is famous for its abundance of sea life. From the colorful corals and sponges, to thousands of species of tropical fish, turtles, rays, eels, sharks, dolphins and so much more. Every dive is exciting because you just never know what you might encounter. Along with the amazing critters, the topography of many tropical dive sites is breathtaking in itself. Dramatic walls and deep canyons are commonplace in many tropical destinations and are a spectacular sight.
7. How do you clean your gear?
(ICE) With fresh water dives the gear does not need a lot of cleaning. It doesn’t even get dirty setting it on the snow afterwards. We use a chainsaw with no oil on the chain to prevent contaminating the water and equipment.
(TROPIC) Nothing shortens the life of your scuba equipment more than improper maintenance and salt water. Thoroughly rinsing your scuba gear is absolutely necessary after diving in salt water to avoid the buildup of salt crystals that are extremely abrasive and will destroy dive gear over time.
Your BCD must be rinsed from the inside and out, if you have items in the pockets of your BCD, take them out to thoroughly rinse with fresh water. If you have a cutting device, remove it from its holder while rinsing to avoid rust build up. Wetsuits need to be disinfected every few dives and hung by a hanger to dry. After rinsing your mask, fins, and snorkel let them dry in a cool dry location to avoid mold build up. It’s important to ensure the dust cap on your regulator is in place prior to rinsing it to avoid water entering into the first stage. In addition, try to keep your gear out of direct sunlight for extended periods of time as this will fade and deteriorate your equipment.
Thank you Dive Addicts for helping us with this post.