27 Dec 2003 20:10:43
Wesley T Perkins
Formula for survivabilty as function of water temperature?

Hello,

I am looking for a formula for the number of hours one can survive in the
water as a function of water temperature and the anti-exposure effectiveness
of the clothing worn (measured in "clo" units).

I have seen references to a fairly simple simple exponential formula (A to
the Bth power) where A and B are some combination of the water temperature,
the clo rating, and possibly some other simple constants.

Any help is much appreciated.


Wesley








29 Dec 2003 10:39:20
Mark Test
Re: Formula for survivabilty as function of water temperature?

"Wesley T Perkins" <wesley@svgcomposer.com > wrote in message
news:7HlHb.11714$IM3.11436@newsread3.news.atl.earthlink.net...
> Hello,
>
> I am looking for a formula for the number of hours one can survive in the
> water as a function of water temperature and the anti-exposure
effectiveness
> of the clothing worn (measured in "clo" units).
>
> I have seen references to a fairly simple simple exponential formula (A to
> the Bth power) where A and B are some combination of the water
temperature,
> the clo rating, and possibly some other simple constants.
>
> Any help is much appreciated.
>
>
> Wesley
>
There is a chart out there in every CIC showing exactly what you are
asking, 32 degrees F <1 hour, 55F <4 hours, etc.,

As for the exact formula I dunno, also I don't believe it uses a clothing
factor.

I ran multiple searches for any info on the web and even visited the USCG
site with no joy. The chart that I'm referring to is from a Navy NWP
(Naval Warfare Publication) and without going onboard a ship and grabbing
the pub I've got no idea how to get copy.

Any SAR guys out there?

Mark
--
"We sleep safely in our beds because rough men stand ready in the night to
visit violence on those who would harm us."
-- George Orwell




03 Jan 2004 11:58:07
Jason Shepherd
Re: Formula for survivabilty as function of water temperature?

More academically, Nuckols Tucker & Sarich (Life Support Systems Design,
Hyperbaric and Divnig Applications, 1996), have a chapter on it.

ISBN 0 536 59616 6





04 Jan 2004 17:36:41
Zak
Re: Formula for survivabilty as function of water temperature?


"Jason Shepherd" <sixbarplus@btopenworld.com > wrote in message
news:bt6aoe$o7m$1@hercules.btinternet.com...
> More academically, Nuckols Tucker & Sarich (Life Support Systems Design,
> Hyperbaric and Divnig Applications, 1996), have a chapter on it.
>
> ISBN 0 536 59616 6

It doesnt really give the chap what he asked for though...

/Zak




05 Jan 2004 11:28:50
rnf2
Re: Formula for survivabilty as function of water temperature?


"Zak" <Zak@nospam.cruelmail.com > wrote in message
news:96YJb.16812$FN.12650@newsfep4-winn.server.ntli.net...
>
> "Jason Shepherd" <sixbarplus@btopenworld.com> wrote in message
> news:bt6aoe$o7m$1@hercules.btinternet.com...
> > More academically, Nuckols Tucker & Sarich (Life Support Systems Design,
> > Hyperbaric and Divnig Applications, 1996), have a chapter on it.
> >
> > ISBN 0 536 59616 6
>
> It doesnt really give the chap what he asked for though...
>
> /Zak
>
>

Their are probably notes in the old WW2 archives... the Nazis in the Camps
threw jews into icewater and timed the period till death at certain temps of
water...

PETA would prefer to bring this back rather than use animals....

rhys






04 Jan 2004 22:19:23
KEY .
Re: Formula for survivabilty as function of water temperature?

Not really formulas but interesting.

http://pedsccm.wustl.edu/All-Net/english/neurpage/protect/nr-dn.htm

http://www.tc.gc.ca/marinesafety%5CTP%5CTp13822%5Cchapter-1.htm



HYPOTHERMIA IN WATER
http://www.adventuresportsonline.com/skihypo.htm
Loss of body heat to the water, is a major cause of deaths in boating
accidents. Often the cause of death is listed as drowning; but, often
the primary cause is hypothermia. It should also be noted that alcohol
lowers the body temperature around two to three degrees by dialateing
the blood vesels. Do not drink alcohol around cold water. The
following chart shows the effects of hypothermia in water:

WATER TEMPERATURE / EXHAUSTION / SURVIVAL TIME

32.5 degrees............................Under 15 min........Under 15
TO 45 min.
32.5 to 40................................15 to 30 min.........30 to
90 min.
40 to 50...................................30 to 60 min.........1 to 3
hrs.
50 to 60...................................1 to 2 hrs..............1
to 6 hrs.
60 to 70...................................2 to 7 hrs..............2
to 40 hrs.
70 to 80...................................3 to 12 hrs............3
hrs. to indefinite
Over
80...................................Indefinite...............Indefinite


PFD's (personal flotation devices / better known as life jackets) can
increase survival time because of the insulating value they provide.
In water less than 50 degrees you should wear a wet suit or dry suit
to protect more of the body.



Per USN Dive Manual

Core Temperature
F C Symptoms
98 37 Cold sensations, skin vasoconstriction, increased
muscle tension, increased oxygen consumption
97 36 Sporadic shivering suppressed by voluntary movements,
gross shivering in bouts, further increase in oxygen
consumption, uncontrollable shivering
95 35 Voluntary tolerance limit in laboratory experiments,
mental confusion, impairment of rational thought, possible drowning,
decreased will to struggle
93 34 Loss of memory, speech impairment, sensory function
impairment, motor performance impairment
91 33 Hallucinations, delusions, partial loss of
consciousness, shivering impaired
90 32 Heart rhythm irregularities, motor performance grossly
impaired
88 31 Shivering stopped, failure to recognize familiar
people
86 30 Muscles rigid, no response to pain
84 29 Loss of consciousness
80 27 Ventricular fibrillation (ineffective heartbeat),
muscles flaccid
79 26 Death





On Mon, 5 Jan 2004 11:28:50 +1300, "rnf2" <rnf2@NOSPAMwaikato.ac.nz >
wrote:

~| >
~| >"Zak" <Zak@nospam.cruelmail.com> wrote in message
~| >news:96YJb.16812$FN.12650@newsfep4-winn.server.ntli.net...
~| >>
~| >> "Jason Shepherd" <sixbarplus@btopenworld.com> wrote in message
~| >> news:bt6aoe$o7m$1@hercules.btinternet.com...
~| >> > More academically, Nuckols Tucker & Sarich (Life Support
Systems Design,
~| >> > Hyperbaric and Divnig Applications, 1996), have a chapter on
it.
~| >> >
~| >> > ISBN 0 536 59616 6
~| >>
~| >> It doesnt really give the chap what he asked for though...
~| >>
~| >> /Zak
~| >>
~| >>
~| >
~| >Their are probably notes in the old WW2 archives... the Nazis in
the Camps
~| >threw jews into icewater and timed the period till death at certain
temps of
~| >water...
~| >
~| >PETA would prefer to bring this back rather than use animals....
~| >
~| >rhys
~| >
~| >
~| >