In a message dated 4/4/2002 9:49:35 AM Eastern Standard Time, siguiriya_at_attbi.com writes: > It would be interesting to know how a wetsuit or drysuit affects the number. > For example, if no protection gets you exhaustion or unconsciousness within > 30 to 60 minutes in 40 to 50 degree water, how would a wetsuit or drysuit > change those numbers? > The U.S. Navy and Coast Guard each received windfall money for cold water equipment studies in the mid-80s. The Coasties did a nice job with a comparison between insulated coveralls (boat crew, "Mustang"-type suits), neoprene wet suits, and dry suits. Very little has changed from the drysuits and wetsuits we had for flying (Navy) over cold water. So the data should be good today. Will try to get it posted in an easy to use manner, but it's '80s data: hard copy. A Navy comparison of dry and wet suits is interesting because of some similarities to kayaking: the Navy judged in-aircraft performance as well as in-water performance in their evaluations. The theory was that a good way to have to test the suit's in-water performance was by having heat stroke while flying. Neither good, therefore compromises. A brief recap: The conclusions of the USCG study are that 1. loose fitting, "wet" , foam insulated protective garments (e.g., a float coat or suit similar to the Mustang) allow lower skin temperatures and faster rectal temperature cooling rates in rough seas than in calm seas because [of] flushing ..... 2. tight fitting, "wet" foam insulated [wet suits] [offer the same protetion in rough or calm seas] 3. "dry" foam insulated garments provide the best protection ..... {and now it gets interesting/jcm} 4. in calm seas, where subjects [are motionless and there is no flushing], the coveralls and the wetsuits provide approximately the same protection; in rough seas, ... the full wetsuit provides significantly better protection than the coveralls. The "coverall" was a Stearns IFS-580, the grandfather of current Mustang suits, from the sound of it. Coast Guard boat crews wore (and wear) them. The Navy article is a study from Approach, the Naval Safety Center monthly. It talks about an operational requirement for a suit that would protect personnel immersed in 45 F water for two hours "without permanent physiological impairment." Basically, a contest between a wet suit and a dry suit, but they have the same coveralls in there, too. A few points --- - core cooling for a shorty wetsuit was one and one half times that of a full wet suit - significantly, core cooling was not significantly different between wet and dry suits, but skin temps dropped faster from water contact, and made the subjects uncomfortable and stressed I'm trying to construct a bar graph essentially as it was published. Scale is 1-7, measuring cooling rate in calm vs. rough; this is data for rough seas 0 1 2 3 4 5 6 7 Standard flight suit (control) +++++++++++++++++++++ 6.46 Loose float coat ++++++++++++++ 4.32 Aviation coveralls ++++++++++++ 3.24 Boatcrew coveralls +++++++++++++ 3.53 Wet shorty ++++++++ 2.40 Full wet suit +++++++ 1.64 Dry suit +++ 0.88 Survival suit ++ 0.74 Nothing absolute here, but some interesting comparisons. And some numbers to factor. Couple of notes: "survival" suits are carried for passengers to put on prior to ditching in cold areas. "Boatcrew coveralls" and "aircrew coveralls" are similar to the Mustang insulated but loose suits. Critical numbers for our discussion --- a full wet suit, the thick neoprene suits that are virtually impossible to paddle in, was roughly half of the protection offered by a dry suit. Discount this for the farmer johns we tend to use, and the numbers were a lot more impressive for a drysuit. Another interesting note --- the stress factor of skin discomfort caused by water flushing within a wet suit was actually measured and quantified. It wasn't core (rectal) temp that dropped, but surface temps --- of far less importance in terms of challenge to survival. (Scientific note: when doing these tests, most labs use "indoor-outdoor" thermometers that are actually just instruments used indoors, but with a probe that is run to the outside to measure outdoor temps --- but read inside. Whatever. In these experiments, the probe is placed --- er, "indoors" as far as the tester is concerned, and the readout unit is strapped to his/her shoulder so that the lab people can keep a close eye on core. Been there, done that: no tee shirt.) This information is somewhat counterintuitive at first --- wet suits and dry suits protect the core at roughly equal levels? Yes, the data show that they do. At least for a while. What the data don't show is the lower stress, far less pain and discomfort, and a more optimistic attitude with the test candidates in drysuits. And that transfers to small motor coordination and other factors. Hope this added some harder data to the discussion. If I can get my act together, I'll put this data together in a usable soft copy with all the details and offer it as a service to anyone who wants to publish it in local newsgroups or newsletters. Jack Martin *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Fri Apr 05 2002 - 22:08:22 PST
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