Staying warm during deco.

[Doc Harry]

...I turn the suit heater on toward the end of the dive -- by the time I'm heading up, I'm completely toasty...

Sounds nice.

A suit heater would be the ONLY way I would be able to get warmed up for deco if I got cold during the dive. Usually it's a downhill slide, once I get cold I just keep getting colder, unless there's a thermocline and a significantly-warmer layer near the surface. I don't mind the 400gm garment and dry gloves, it's worth it to stay warm.

 

[EMiles]

Wrong!

If you're cold during the bottom phase, forget about getting warm and staying warm during deco.

Getting cold is a risk factor for DCS. Stay comfortable throughout the entire dive.

More air in the drysuit = warmer

Muscle activity generates heat, continuous finning and/or helicopter turns will generate warm

Check out the research. Being colder on the bottom than on deco is safer due to perfusion. Thermal Physiology and Protection | Rebreather Forum 3

 

[DCBC]

Short of using a hot-water suit, I'd recommend a mixture of the following (dependent on your susceptibility to cold, dive duration, water temperature and breathing gas):

Dry Suit - Thermacote (Ti-Ax) heat-reflector on the inner layer of the Dry Suit
Inner Layer - Polypropylene (especially next to the feet, hands and head), Helly-Hansen Lifa Prowool or an Xerotherm base (developed for NASA)
Middle Layer - Fleece or wool mid-layer (again HH Merino wool or a 4th Element) A Buddy uses a 4thE Arctic one-piece with a 4thE SubX and swears by it (though it's a little bulky). His suit flooded last year in the middle of the dive (up to his knees) and he said he was still warm...
Outer Layer - I use a 4th Element Halo3D as my outer layer with an Xerotherm Inner. The water temperature at depth here is usually between 31 and 48 degrees. Even though my dives tend to be long with Helium, I can't say that I've ever been really cold (although chilled at times).

 

[GDI]

Cold (increased risk of DCS) Movement, Exercise, physical work load (increased risk of DCS), Poor blood circulation (increased risk of DCS) hell waking up in the morning (increased risk of DCS) - you get the idea. Wearing a battery operated hesting vest or suit is a good idea. So does the Hot-water suit if you have the logistics and surface support staff like commercial divers.

I prefer to be a constant (relatively) temparature throughout the entire dive. At bottom depth I move exerting the least amount of energy possible. If I break a sweat I adjust my pace to regulate the body core temp. How I dress is based on the known or speculated bottom temp and assume this to be constant throughout the dive. Maybe not the best approach but it works for me and can be adjusted to the local diving scenario. This method or thought may cause me to be concerned on the surface to avoid overheating (heat exhaustion sucks) but I just pace myself and work to getting into the water; again with the least amount of energy.

During the deco phase if I have paced myself correctly from start to finish I will be comfortable and not expend much energy moving around. This is because I believe it is always easier to cool down on a dive then to warm up, thus I will slightly overdress and layer my undergarments to allow me to rest during deco phase and not have to move much if at all. I will occasionaly stretch out to ensure blood flow/circulation and even loosen off my harness straps shrug my shoulders et all to help circulation.

Also Keep in mind that I try to remain horizontal during deco. In this position it really doesn't matter if you are adding air or argon to your suit as the gas will raise towards the upper sections around your back leaving your chest against the material of your undergarment and drysuit. Becuase of this I will wear the required layers and type of undergarment to ensure protective layers and thermo qualities based on the local conditions. If I am too hot/warm I can always pop a seal carefully to cool down, Just removing a mask to feel the coolness of the water can make a difference in temperature regulation. Your undergarments need to be able to handle wetness and retain thermo protection.

I use the acronym C>O>L>D C= Clean, O= Over-heating avoidance, L= Loose and in Layers, D= Dry. Clean undergarments hold better thermo protection then when soiled in body sweat etc. Avoid overheating by regulating your movement and work effort, Pop a mask seal to keep cool when needed. Loose and layered undergarments of the right type of material will go a long way in control thermo stress, some material wick away sweat. Stay dry as air is less conductive of body heat then dampness- keep your suit in good repair and working order (how many os us have leaking dump valves????)

 

[DCBC]

...Your undergarments need to be able to handle wetness. ...Clean undergarments hold better thermo protection then when soiled...

So remember not to soil yourself and invest in a P-Valve...

 

[Superlyte27]

here is some news none of us wants to hear:

you want to be cold during your bottom phase of the dive!

here is the news that we want to hear:

You want to be warm during your ascent and deco part of the dive!

Why? Because you on-gas less on the bottom phase and off-gas more efficiently during your ascent and deco phase of the dive.
This "news" is particularly pertinent to us deep divers with long deco! It will decrease your risk for dcs. The study was done at nedu.

Sorry to side-line your post, but i had to share the news :d

that being said, i hate being cold! I believe in layering. Why? Because (just like in skying, mountain climbing, etc), you need to have a wicking layer as your first to get rid of moisture. Moisture on your skin will chill you! That is why cotton is your enemy! In mountaineering: "cotton kills". Then you add progressive layers that have different thermal qualities. I recommend looking at the materials that 4th element sells. If you go on their website, you will get a bit of an education on thermal wear and help to chose what you may want to wear. I

if you live in europe and can get your hands on xbionics ski stuff, i highly recommend that as your wicking layer.

Cheers

uh no!

---------- Post added June 17th, 2013 at 02:17 PM ----------

Can you provide a reference for the study you've cited please?

No, because it's bs

 

[JohnN]

I used to use Argon, and it helped.

But it's spitting into the wind compared with suit heat.

You want to get gradually colder during your bottom time, but you want to be as warm as possible during deco. I turn the suit heater on toward the end of the dive -- by the time I'm heading up, I'm completely toasty. I am using the Santi heated vest, with an NiMH battery. It is worth the rather nausea-inducing cost involved.

You should check out the DUI "Blue Heat" pricing if the Santi makes you gulp. . . . .

 

[GDI]

So remember not to soil yourself and invest in a P-Valve...

oui oui d'accord mon vieux certainment

 

[DCBC]

oui oui d'accord mon vieux certainment

C'est toujours mieux que vous ne le faites pas chier ou pisser vous-même.

BTW, the greatest majority of all Canadians don't speak French. It's a good thing that it's my wife's first language. Nothing like a French Gal...

 

[Wannabedivebum]

Great information guys! I was pretty close to making the heated vest purchase last winter while diving, But everytime I see the price tags I tell myself I wasnt thaaaaat cold on the last dive =P