This same subject came up a year and a half ago on the tech list (Sept=20
98).  What follows is my reply to the subject then.  As my experience=20
continues to grow so does my certainty that electric underwear is an ill=20
advised idea at best!

On Sept. 7, 1998 I wrote:

I have been following this thread for days now watching for some sign that=
=20
someone has even a remote idea what cold water technical diving is.  It is=
=20
sad that the best advice came from a diver that by his own admission is a=20
"sport diver (no decompression)".

For those of you that are not aware, most of my technical diving is in the=
=20
Great Lakes with bottom temps around 38f.  My bottom times range from 20 or=
=20
25 minutes to over 90 minutes.  Deco times range from 0 to nearly 2=20
hours.  And average run times for my Great Lakes dives are about 90 minutes=
=20
with some longer and some shorter depending on the dive objective.

The best way to stay warm with a flooded suit is not to dive cold=20
water.  Heaters, chemical or electric, are unreliable at best.  It does not=
=20
matter what you wear under a dry suit if it floods in cold water you are=20
going to get cold!!!  Good undergarments will help a lot but they will not=
=20
prevent the stinging cold from running across every part of your body as=20
the water seeps in from even a pin hole.  I know I have been there.

Several thin layers of Thinsulite or wool are MUCH better than one thicker=
=20
layer. Polartec is also a choice.  Again the thinner the better.  Garments=
=20
that use Mylar or Titanium thread or foil will still work by reflecting=20
your body heat back even when wet.  However, Mylar and Titanium will be of=
=20
little use if they are not warn close to the skin.  If they are the second=
=20
of third layer they become nearly useless if the layers under them get=20
wet.  These are the only materials that will get the job done when=20
wet.  However, even the best layering and the best materials will not keep=
=20
you warm.  Again, YOU WILL GET COLD!!!  It just becomes a matter of how=
 cold.

I have tried chemical heater packs in the past.  The best ones are the=20
liquid filled silicone bladders.  However, they have a little quark about=20
them.  The colder they are the less heat they put out.  Mind you they last=
=20
longer when cold but who cares when you are BTU deprived.  The other=20
problem with them is they are hard to activate inside a suit.  That problem=
=20
becomes even greater when you and your hands are numb.  Imagine, if you=20
will, trying to find a dime under two layers of clothing when you can't=20
fell the tips of you fingers.  You need to find the dime then bend it or=20
snap it to activate it.  Good luck.  What will happen is you will loose=20
sight of what you need to do to get your deco done as quickly as=20
possible.  You start poking at the area you think the dime might be.  All=20
the while wasting valuable time.


The other type of chemical heat pack is activated when it is exposed to=20
air.  These work well for hikers and others on dry land.  But in a dry suit=
=20
they are about as useless as tits on a bull.  First they must be activated=
=20
before you enter the water.  They are stored in air tight packets that once=
=20
inside a dry suit can not be opened by a diver in the water.  I'll pay to=20
watch you try though <g>  So you open this thing stick it inside the dry=20
suit then gear up.  The whole time this thing is cooking away.  Then as you=
=20
enter the water the increased PPO2 puts this packet into over=20
drive.  Unless you use Argon for suit inflation.  In which case the damn=20
thing stops working altogether.  Either way the minute these thing get wet=
=20
they stop working.  Don't bother with these either!!!

As for electric britches...  What Zambeckian moron came up with that=20
idea.  Oh I remember.  That was the idea that spawned the phrase Zambeckian=
=20
Moron.  Nice work Greg.  Folks I have been involved in electronics for 22=20
years and I can tell you from a great deal of first hand experience that=20
electricity and water do NOT mix.  Just when you need your electric pants=20
the most they quit working.  Worse yet they might start to heat something=20
you don't want heated!!!

So what do you do!!!  As with most things in diving experience will be your=
=20
best teacher.  You will get wet a few times.  Find YOUR limit with shorter=
=20
dives first.  Once you know how long you can be cold you will know how long=
=20
your dives can be.  Things that can help are to eat properly before a=20
dive.  It is incredible how much your body can take when properly=20
nourished.  I once lost over 7 pounds on a 20 minute ice dive.  I haven't=20
been in a wet suit since!!!  Carbs are the best fuel for cold water=20
diving.  Pasta the night before and whole grain pancakes for breakfast are=
=20
my first choice.  Fats and sugars are a poor source of fuel and should be=20
avoided.  If you do get wet you will need plenty of the best fuel you can=20
get to keep from succumbing to hypothermia.

If you do get cold keep moving even if only slightly.  That does not mean=20
swim around as fast as you can.  It means move your extremities=20
SLOWLY.  Your hands and feet are the first things that will lose the blood=
=20
supply if not used.  If your body starts to shunt blood from these areas=20
they will not off gas and a nasty case of bends is the likely=20
result.  Neurological damage is possible, I have personally seen it=20
happen.  If you must hold on to something while on deco switch hands=20
OFTEN!!!  If you can use a "jon line" and free up your hands.  Keep every=20
part of your body you can in GENTLE but CONTINUOS motion.  This will help=20
to keep blood flowing to the extremities.

If you start to feel sleepy you may wish to consider getting somewhere dry,=
=20
QUICKLY!!!  Sever hypothermia can cause loss of consciousness.  So unless=20
you have learned to breathe water, your bends may be easier to treat than a=
=20
drowning.  I feel that death puts a damper on the fun!!!.



At 12:01 PM 5/9/00 +0200, Ingemar Lundgren wrote:
>Do you know how much it will cost approximately?  Sounds like the same
>approach Typhoon in UK is using for a similar product. Is DUI making it
>under license from Typhoon maybe?
>
>The Typhoon electrical costs about $1550 in Sweden so it's really=
 expensive.
>Does anyone know how much the Typhoon costs in the UK?
>
>-----Ursprungligt meddelande-----
>Fr=E5n: Trimixjoe@ao*.co* [mailto:Trimixjoe@ao*.co*]
>Skickat: den 9 maj 2000 00:41
>Till: cavers@cavers.com
>Kopia: techdiver@aq*.co*; Gagdive@ao*.co*; EANX@ao*.co*;
>lakeexplorer@ya*.co*; doppler@te*.co*
>=C4mne: Electric Underwear.....
>
>
>Hello All,
>Just wanted to bring up a new piece of dive equipment that is soon to be
>offered to the diving community. This weekend I got the first chance to=
 test
>out a new underwear that is electrically heated! It is being marketed
>through
>DUI and I have to say it has some great possibilities. It is the same
>material as a skin but has 5 heating elements. 2 heaters on calf's , 2
>heaters on the forearms and one large heating element near the lower back.
>The 5 heating elements are attached to a brain box that regulates the 5
>elements individually (which is programmable). From the box it has a wet
>connection to the dry suit, on the drysuit there is an external wet
>connection that goes to a battery hook up. On the drysuit there is an on=
 off
>turn switch which is nice. I took it for a test dive in 50 degree water and
>it was quite comfortable and warm. There is a lot more about the suit
>function and specs that this e-mail doesn't cover which may be best
>described
>by the DUI rep. I just wanted to say it will make these very long deco's a
>piece of cake!
>
>Joe Rojas

Bill (aquadart) Bott

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