Heating systems - many deco risks?

CharlieT

I bought a Typhoon heated waistband for last winter for £100 which has two heat pads for your kidney area.

You switch it on before you close your drysuit and it lasts for about 2.5 hours which either covers all or a good portion of your dive. Quick recharge.

It doesn't require a hole in your drysuit which then becomes another potential leak, doesn't affect buoyancy, isn't bulky, isn't expensive.

It turned a very cold and unpleasant end to a 90 minute dive in 7C to a warmer and much more pleasant experience.

No, it's not in the same league as a heated garment powered by a Metalsub battery!

Since Metalsub batteries can come with two plugs, to run an HID 200 lamphead and a heated garment from one battery would be pretty cool. No reverse pun intended.

Charlie

denzel

Where's Wally?

link: Building electrical Drysuit heating-stuff

Have a look there.

Denz.

__________________

CharlieT

The other extreme to the very simple device I use

I can see how easily you could cook yourself. Medium rare, anyone?

Charlie

johnv

I think I said it wasn't ideal, but the battery doesn't _have_ to last the deco.

you can buy heated suits, socks and gloves, some of these heat the extrimities NOT the core.

John

johnv

I VERY strongly do not reccomend putting any type of chemical heating you cannot turn off inside your drysuit. I know of someone who got burned using the chemical warmers in their boots because they could not remove or turn them off.

John

Janos

There was an interesting presentation at this years DOC from a hyperbaric doctor (from Hull IIRC) who was talking about some of the injuries they are beginning to see as a result of recreational divers going "deeper for longer".

One of the injuries that is becoming more common is "Non freezing cold injury" or trenchfoot. However they are seeing cases in recreational divers hands, not feet. IIRC the Navy have heated gloves to keep their hands warm.

Personally I think the best situation is to be warmer on deco than on the bottom. The best solution would be a heated vest that you could turn on when you got to your stops.

Janos

__________________
You can lead a horse to water but you can't climb a ladder with a large bell in both hands - Vic Reeves
www.hellfins.com/shed

Faceless

Here is Russia there is a famous ice-diving center based on White Sea called ( you bet ) "The arctic circle".
I've not been there by myself (yet, definitely hope next year ) but have met some people from manager's staff, and they're claiming succesfull & extensive use of heating jackets made from FiberThermics, tailored in Russia.
Here is their site: Ice Diving and PADI ice diving course in the North Russia Arctic Circle

UPD: link to the manufacturer of material: ThermoSoft - Press Release Oct. 23, 2001

__________________
Peoples risk perception is almost always focused on the most dramatic rather than the most probable. (c) Gordon Smith

Mdemon

If I couldn't have it on for the whole dive then this would seem to be the preferred solution.

However, the reason I asked the question originally was because if you increase the heat then you effect the ability for liquids to hold dissolved gas (I think!) and you also increase the blood flow. I wondered if there was an increased deco risk in turning on the heat at the end or maybe the reverse? From the number of users here, it would appear not. Would welcome a HB doc's view...

The flip side, I guess, is that if the blood flow is reduced because your extremities are shutting down because you are so cold then you are going to be offgassing less efficiently etc etc and are more likely to get bent.

__________________
www.southwestmafia.com

"small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!"

The WRONG Attitude will get you killed.

"Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"

AD_ward9

<EDIT: See warning on use of carbon self limiting material posted separately>

We have a client with heated undersuits and the usual mass of hard data this sort of activity generates might can save a burn or two to others doing the same thing. The client involved has committed to the Open Revolution ideal, so I will have a word with them to find out what we can publish and when: there are three other organisations involved with NDAs at the moment. We also tried doing this during expeditions over the past four years.

Meanwhile, here are some useful pieces of information collected along the way:

1. Suit heating was tried a lot with commercial divers in the North Sea 20 years ago. Many still have the burn marks to prove it! Using a wire heating element in a dry suit operates very differently to the electric blanket on a matress. The effect of cold surroundings and pressure from your harness means you can burn without noticing it. By the time you get out of your test dive, it may be too late.

2. There are a number of companies making self stabilising heating materials, such as from EXO2 and some Russian sources. These use a carbon loaded material which increases in resistance dramatically with temperature. If you do this sort of thing, this is what you need. You need about 100W of heating to be worthwhile, otherwise buy an Aerogel undersuit: safer and very cosy.

3. During deco you generate very little body heat, compared to doing something actively on the bottom. The heat generated within your suit from different levels of activity will change your body temperature more than 100W of external heating, so deco issues are probably not that much different from a diver who has worked hard on the bottom, wrenching that artifact off etc.

4. Chemical heaters should not be used. The chance of serious burns is very high.

5. Ice climbing and skiing gel heat storage pads are also not a good idea. When pressed or decompressed, the amount of heat these gel pads release changes considerably.

Alex

RAL

I use hot water regularly on gas dives. Personaly I prefere to not use the hot water any more than is needed on the working portion of the dive unless it is bitter cold, using it most often on the last portion of the deco.
If you start the dive with it then lose it you will be way worse off then not having had it at all IMHO. If you do chose to use some form of heat don't put yourself in a position that will make you have to chose between getting bent or risking hypothermia if you loose it. Dress to make the dive as if you do not have it & consider it a bonus if it is there to warm you up a little on deco.


RAL

__________________
The sea does not care about you.