Chemical Handwarmers with Drysuit???

[DanL]

Can those little heater packets - handwarmers and toewarmers used in gloves and boots - be used inside a drysuit for extra warmth?

[Chris]

I've heard of people doing that, never actually seen it being done though. I guess I can't see why not.

[FMT]

Realistically, the answer is no. I have tried it and
they do not work. The reason is that they require
oxygen to work their heating "magic." There is some
oxygen in your drysuit if you inflate with air but
there does not seem to be enough "flow" within
the drysuit to supply the needed O2. You can try
this in your coat pocket as well. If you do not
take them out and move the chemical around
every so often (supplying it with fresh O2) they
stop working until you do.
Too bad, I wish they did work. :'(
Todd

[DanL]

Todd,
You're right, that type needs O2. There are two new types out (at least I've just seen them). One is reusable and has sodium acetate in a solution inside a sealed vinyl bag. You click a small metal disc inside the bag and the sodium acetate solution starts to crystallize, turns solid very quickly and generates heat - up to 130F, but no hotter. Heat supposedly lasts an hour plus. After they solidify and give up their heat, you boil the bag in water for about 5 minutes to remelt the solidified salt. It then cools down, but doesn't recrystallize until you click the metal disc again for the next use. The solution is NOT toxic and is harmless if the bag should leak. Cost is $3.49 at WalMart. They seem to work well, but I'm not sure they generate enough heat to keep hands warm in a dry glove. I'll be trying them in an ice dive next weekend. Plan to put one on the back of each hand inside dry gloves.
The second new type was also at Wal Mart, but I didn't buy them. I plan to tomorrow. They are also a palstic bag and heat based on mixing of two chemicals. They are NOT reusable and I don't know how hot they get. I also don't know if they are toxic if they leak, or the price. I'll post that tomorrow with a "heat output" comparison of the two types.
Neat thing about each is that they are sealed and waterproof, so should work with wetsuits or dry. Also don't require oxygen - self-contained reaction in the bag gives the heat. Hope one or the other of these little defrosters work!
Anyone else tried the above or have something to add here?
DanL
Todd - welcome to the board. Where are you from? - sounds like you know cold water...

[FMT]

I'll have to try the metal disc ones. I know
they have been around for a while but they
were always too big before. I'm from S.
Mpls and I do a lot of local diving,
as much as I can. I can see great value in
the handwarmers if they work, particularly
diving Lake Superior this time of year.
Todd

[DRE]

Be careful though using them at greather depth - a friend of mine actually burned his hands, I'm not sure whether they change their heat output at greater pressure or maybe it was just the kind he was using.

[DanL]

DRE & FMT-
I'll be playing around with the sodium acetate warmer - let's call em "salt packs" for short - this weekend. Plan to take one down under one dry glove with a glove liner between me and the salt pack. Will see if I notice a difference. The size is 3 x 4.5 x 1/2". Fits across the back of my hand, but don't know yet if they will fit under a glove (haven't received my drygloves yet). If no fit under glove, I'll put it inside my sleeve/bottom of wrist, just above the wrist seal.

Ran a test with one today. Activated it, put it between two pieces of foam insulation. Temps went up fast: 75F at start, 122F in 5min, 127F within 20 minutes. 127F was the max. Took off the top insulator at 20 min. and kept measuring the temp between the salt pack ad the bottom insulator. At one hour, temp was still 118F.

Activated another pack and held it tightly to inside of my wrist, directly on skin, and it never felt uncomfortable. My concern is they may not generate enough heat to make a big diff.

DRE - your friend's burn could have come from pressure at depth making the skin contact VERY tight. Or the reaction may go faster under pressure, but I doubt that's it in this case - the salt rxn can only generate about 130F max (although I do need to brush up on the pressure effect). But if he used an O2 activated heater, and there was enough air in his drysuit, then at depth the higher partial pressure of O2 definitely would push the reaction faster and drive the temp up. Those iron/air heaters can get hot at 1ATM if they get enough air.

FMT - what kind of diving do you do? I do cold water, Crosby/Wazee/Superior, no-penetration wreck, drysuit, EAN40, 130ft max, and after this weekend - ice.
Cert -PADI Rescue and various specialties.

I'll see what more I can find out about the salt packs and post. Warm hands and feet sound good.

Dan

[FMT]

I picked up a couple of the NaC2H3O2 warmers at Wally World and did a dry-land test with them. I think they might work well with a layer between you and them but they are still very bulky trying to fit in my dry suit boots or dry
gloves. They also had some non-O2 "Toasti Toes" foot warmers which are MUCH less bulky but I have not tried those yet. I will try them next Sunday on an ice dive.

I haven't dove outside of MN/WI/MI since 2001 and I rarely dive in a wetsuit (maybe in August at square with the kiddies) so I'd definitely say I'm a cold water diver. I'm concentrating on my technical diving (Wazee/ Lake Superior) building up to dive the deep wrecks. So between that, O/W students, Lake Superior charters, and a trip to FLA it looks to be a pretty busy summer. YES!
Todd

[freedivernd]

Hi Dan,

Say, are you putting together a report on your ice diver certification? I'm really wondering how it went. That not being able to see the hole is somethin' isn't it? How was the light, the vis, the temps, the depth, the time, the surface... did you freeze your fins off? Any wetsuits in the group? Anyone else from the board there? Anyone there going to join the board... I see we're pushing 200 registered.. wow.

Fred

[DanL]

Fred,
Ice dive report:
A lot of work to prep hole - auger 3 holes, chainsaw 3 sides of triangle, get rid of big heavy chunks of ice, haul a s**tload of equipment across a slick surface, set up lines, etc.
Then - a great diving experience!
Actually I can't complain at all. The group that Tim Thomas pulled together was great. Everybody pitched in to set up. In addition, Tim arranged the dive with the Dakota County Sheriff divers. They had a heated trailer, heated ice houses, great surface equipment, etc. The sheer number of people made the complex dive logistics easy.
Sat temp was 4F. We dove Lac Lavon - 14ft max D and nearly zero viz. Very spooky because due to overcast day and low viz, all you could see was a ball of hazy light above. Spent most of the dive on my back watching the glow.
Nearly all divers had freeze-ups before even getting in the water and most aborted diving. My Apeks was fine, but I think its because I "heated" it in the 33F water before turning air on, and I kept the first and second submersed before breathing the reg.
Drysuit and gloves essential, not only for warmth in water, but to keep from freezing to death on the surface. Everything freezes almost instantly after being pulled out of the water.
Sunday high was 4F! With wind!!! Went to Sq. Lake seeking better viz, but it was maybe 10 ft max. Had good dives, great surface support, again due to Dakota Co Sheriff equipment and personnel. Had a 24 min dive and never felt cold. The drysuit and gloves are amazing.
Very few probs with regs - everybody immersed regs in water and waited until they "warmed up" before breathing.
Tim is great at keeping things moving fast - we got set up, made dives, tore down and headed home in plenty of time for the SuperBowl.
Fred, I was within a couple of feet of the hole and could barely tell it was there. You have no margin for error on free ice dives. You definitely should have a TAUGHT guideline to the hole AND a harness and lifeline. Lecture over...
Net - great fun and I want to do it again, hopefully with better viz.