Upon the prompting of Keith to contact Dr. Giesbrecht, I sent the professor an email today on the availability of data related to the thermal differences between wetsuits and drysuits. I received his prompt response only a few hours later. In my email I quoted a portion of the response that I received from the Kokatat company, that I posted to the list earlier today. This is the "company who responded" to which Dr. Giesbrecht refers. Dr. Giesbrecht's response follows. (Hopefully the formatting on the data table won't be too messed up): - - - - - - - - Jim. The company who responded should know better, there is a lot of work done on wet and dry suits. Basically, for the same insulation value a dry suit will keep you warmer than a wet suit because the cooling water does not flush heat out of the dry suit like it does in a wet suit. Some of this work is described in a chapter I've co- written as follows: 1. Steinman AM, GG Giesbrecht. Immersion into cold water. In ed. PS Auerbach, Wilderness Medicine Management of Wilderness and Environmental Emergencies (4th edition), Mosby, St. Louis. Pp 197-225, 2001. I do have a computer model written by a Canadain Defence Scientist that compares cooling rates as follows: I input a 35 year old man weighing 70 kg, 1.8 m tall, 17% body fat immersed to the neck in 5°C water. Results as follows: time to reach 34°C time to reach 28°C light wetsuit 2.8 hours 5 hours heavy wetsuit 4.5 h 7.3 h drysuit light undergarments (dry) 18.1 h 24.3 h drysuit heavy undergarments (dry) > 36 h > 36 h NOTE the difference if you do a drysuit light undergarment (completely wet, i.e. a big leak) from 18.1 to 1.4 h from 24.3 h to 2.9 h Hope this helps. Gord - - - - - - - - - - - - Dr. Giesbrecht's response ends here. Given that there are many variables here, I was impressed by the difference provided by the drysuit based on the computer model. It was actually much larger than what I would have expected. In thanks to Dr. Giesbrecht for his response, I would like to quote a reader's review (from Amazon.Com) of the book to which he contributed: "Foregoing knowledge of the existance of this text was unkown, until it was needed in an emergent situation on site. At that time a stingray injury required our immediate attention. With no previous experience in this kind of injury, the book provided immediate no frills information on treatment, backup care and procedures. After this experience, I carefully examined the text at length and was amazed at the comprehensive nature of the topic that was covered. I would recommend this text to be present in all health care provider libraries and offices, as it is in mine. Dr. H.J. Willis D.O. Emergency & Trauma Physician" jim holman *************************************************************************** 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/ ***************************************************************************
Looking at the thermal conductivity of air verses water it is not at all surprising: Air = 0.000057 (cal/sec)/(cm^2 C/cm) Water = 0.0014 (cal/sec)/(cm^2 C/cm) http://hyperphysics.phy-astr.gsu.edu/hbase/tables/thrcn.html That is a factor of 24x Clearly you are much better off with air as an insulator than water if cold is the only factor. No surprise as well that everyone I know claims to be much warmer in a dry top than even a full wet suit. We often use our wet suits when rock gardening anyway because of protection they offer from jagged (and very hard) rocks compared to a dry top. One sharp rock can turn a wonderful dry top into a very lousy "wetsuit". Steve Brown ....Given that there are many variables here, I was impressed by the difference provided by the drysuit based on the computer model. It was actually much larger than what I would have expected. *************************************************************************** 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/ ***************************************************************************
> 1. Steinman AM, GG Giesbrecht. Immersion into cold water. In ed. PS Auerbach, > Wilderness Medicine Management of Wilderness and Environmental Emergencies > (4th edition), Mosby, St. Louis. Pp 197-225, 2001. > > I do have a computer model written by a Canadain Defence Scientist that > compares cooling rates as follows: > > I input a 35 year old man weighing 70 kg, 1.8 m tall, 17% body fat immersed to > the neck in 5°C water. Results as follows: > time to reach 34°C time to > reach 28°C > > light wetsuit 2.8 hours > 5 hours What stages happen at 34C and then at 28C (from stiffening of limbs, i.e. you start drowning if in water, and up to the heart stop)? If person can live and swim for more than 2 hours in a light wetsuit (presumably full suit, not FJ?), - that's surprising; I thought we have much less time. Also, please note: "immersed to the neck". In reality his neck would be washed with 5C water a good number of times. Alex. *************************************************************************** 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/ ***************************************************************************
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