Posted by Faith on August 29, 19101 at 21:39:03:
In Reply to: Re: Something I'd like to pass on posted by Paul Ehorn on August 29, 19101 at 19:27:26:
: : I am posting this message in hopes of making other divers aware of a danger in diving that is farely new to the sport of scuba, but has tragically resulted in many diving fatalities. What I am referring to is respiratory shock. Being a diver myself, I was aware of narcosis, the bends, an air embolism, the list goes on, but respiratory shock was something I'd never heard of. Until I lost somebody I loved very dearly due to respiratory shock. What many divers do not realize is the effect that the water temperature has on your air supply. Diving in 75 degree water can drop the temperature of every breath you take in to 25 degrees F...well below freezing. Obviously, 75 degree water is almost unheard of in Great Lakes diving, so keep this in mind. The fatality I am speaking of, occured in 34 degree water. Most of us would say, "What the heck was someone doing diving in water that cold?". Looking at a wreck...in very deep water would be the answer. The temperature of the air you breath with the water temp only being 34 degrees is a frigid -15 degrees F. Take into consideration, that no matter how well you are insulated outside your body, that air is cooling your body INternally. And this can happen to any of us on any dive. Remember, 75 degree water=25 degree air. What happens when the body cannot compensate for the extremely cold air? Respiratory shock. The wind pipe freezes, constricts, and restricts the amount of air that can come in and be released. Most likely, the diver will have no idea of what is going on and will probably be blaming the problem on a faulty regulator. The problem lies when the diver then attempts to ascend, at which point, the lungs cannot expel the air quickly enough because of the restricted wind pipe causing massive air embolisms. It is now being speculated that many diving fatalities that were caused by air embolisms without ever actually knowing how the embolisms occured were due to respiratory shock. It is scary to me to think about this. Knowing that once your body can no longer keep up with the cold air you are breathing, there is nothing you can do. We are talking a matter of seconds here. The solution, I suppose, lies in finding a way to warm the air in our tanks, which seems almost ironic since the tanks are completely submersed in water. I tell this story, not because I have a solution, but because I would like to make other divers aware of this all to common, but rarely heard of, occurence. Deep diving may prosper more-intact wrecks and Lake Superior (being the coldest of the lakes) may have the fewest zebra mussels, but the cold water can be all too dangerous even for those of us in dry suits with ample insulation.
: : I plan to do more research on this subject, and anyone with more information may contact me personally or post a message.
: Faith: I do not know who supplied you with the 34degree water temperature at depth. This number is virtually impossible unless you are diving under the ice. Water has a density of 1.000 at 4 degrees centigrade (39.2 degrees fahrenheit), the density is slightly less than 1 at all other temperatures. This means that if water is warmer or colder than 39.2 degrees fahrenheit it is lighter and floats, this is the reason for ice floating in the winter months and the warm water being at the surface during summer months. To have 34 degree water at depth it must be colder all the way from the surface to that depth. This would mean that the surface water most likely had to be frozen. Try 39.2 degrees fahrenheit for your calculation as it is much more reasonable, enough for the physics lesson.