At 06:35 PM 8/26/99 -0700, "Ron Sallee" <ron.sallee@kendra.com> wrote: >Please take a scuba class. A dangerous misconception is that "shallow" >water is less dangerous than "deep" water. The principle danger in >breathing pressurized air underwater is lung expansion injury leading to >embolism and quite possibly death. The greatest expansion in volume occurs >in the in the last 10 feet to the surface. People have died from lung >expansion injuries sustained while ascending the last few feet to the >surface. You are right to be concerned about oil contamination but the >danger of embolism is far greater. Amen to that. If you take this powered snorkel down to four feet, take a full breath and hold it while coming to the surface, you may die. If not, you will be seriously hurt or crippled; and you will spend some serious time under close and expensive medical care. I've seen all this happen, with the victim never getting deeper than ten feet. The single most important rule when breathing underwater is to keep breathing at all times, and to never hold your breath. That sounds so simple, but then it is also so simple to forget and hold your breath. If you do this even momentarily while coming up, then that can kill you quicker than any other diving accident or equipment malfunction. I've done a number of "free assents" from 120 feet. It is a game that Cindy and I used to play in a 120 foot hole that we used to dive in a lot. I would open my valve only a quarter of a turn, so that she could quickly turn it off. She would then do this without warning at some point in the dive, and I'd do a free accent. She would follow closely, so air was very close if I needed it. The point is that I never needed it, even though I've taken as long as six minutes to complete the free assent to the surface. You exhale all the way to the surface, stopping the accent once in a while to exercise the lung mussels, under the theory that prevents certain potential lung problems. During the last ten feet, you do more than exhale. You blow and blow hard to prevent your lungs from expanding. Even though it took up to six minutes to come to the surface, I never felt short of air, since the air in my lungs was continually expanding the entire time. I've included this paragraph only to illustrate how much the air in your lungs expands when you come to the surface. If you don't let it out, it can kill you. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ :: Paul and Cindy Kruse :: KJV Joh 14:27 Peace I leave with you, 165 South Kenneth Court :: my peace I give unto you: Merritt Island, FL 32952 :: not as the world giveth, give I unto you. E-mail: plkruse@iu.net :: Let not your heart be troubled, 407-453-6206 :: neither let it be afraid. :: +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++