[Paddlewise] Cold water: actual data

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





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