How do you stay warm on a dive?

[kenny kustom]

I dive a 7mm full suit w a vskin under it, into the low 40's.

Next weekend will be in the high 30's.

 

[Jerry_]

Wetsuits:

While being younger I dove with a 7mm neoprene wetsuit and 5mm hooded vest down to the low 40s F.
Both in summer and winter I put a thin surfboard nylon dress - basically I bought it for easying to put on the wetsuit, but in winter it also helps for keeping the warmth, as water is captured in the nylon and does therefor hardly circulate.

The coldest dive I ever did was in January/February when we went down to 120' in a cold quarry.
The reason being that neoprene was compressed by the ambient pressure in the water, which made it loose almost all of its insulating qualities.

Also neoprene will loose its overall insulating capacities when it gets older (8 years plus), so buying a second hand neoprene wetsuit might not be that good idea.

Drysuits:

My first drysuit was a trilaminated one.

The trilaminated wetsuits do little thermal insulation by itself and therefore require some thick undergarnment. The issue with thick undergarnment is, that it will increase the air trapped in your drysuit. Therefore, at least when having to take decostops, they are fairly uncomfortable, as either you dive overweighted or you get cold when taking the decostop in shallow water.

Actually I have a 4mm compressed neoprene drysuit and some lightweight undergarnment. That suits me best as it doesn't much hinder your movements while still allowing for a comfortable dive.

I had discussions with buddies who are diving with thicker drysuits, but all mentioned that this was hindering their movements (f.i. Palming)

To be seen how and where you dive, in order to decide what suits you best.

 

[Foxfish]

I dive a 7mm full suit w a vskin under it, into the low 40's.

Next weekend will be in the high 30's.

Sounds cold! What is a vskin.

 

[DivemasterDennis]

Dive in water 85 degrees or warmer. If you cnt, then this is my exposure gear pattern :

75-83 degrees, 3 mil
65-74 degrees 5 mil
55-64 degrees 5 mil over 3 mil hooded vest, 3 mil gloves
below 55 degrees, dry suit.

Also, always get dry, peel down and warm your core in the sun between dives.
DivemasterDennis

 

[tracydr]

Here's what I do:
3ml- above 80 degrees
5ml-75-80, with hood and gloves for 75
trilaminate drysuit with various undergarments-less than 75, I prefer my drysuit for anything less than 75 degrees. I would even wear it in warmer temps, but usually the ambient air is so warm that I can't comfortably get into the drysuit at warmer temps without having heat exhaustion ( AZ, summer in the 110 degree range)
My first year of diving was in Puget Sound with a double layer Farmer John type 7/7 ml wetsuit ( 14ml on the core),that I rented from the Military dive shop. I'm so thankful for my drysuit now, I'd never go back to that. I love my drysuit!
I really like that I can change the undergarments to make myself comfortable at any temperature.
Now, if I could figure out how to stay "cool" until I get in the water.

 

[Steve_C]

Related point on staying warm. I dive wet. When in cooler water I find body position makes a difference. When trimmed out I have my bent arms pressed lightly against my body instead of out slightly as I would do in warmer water. This seems to make a noticable difference in how cool I feel.

 

[lowviz]

...//... Now, if I could figure out how to stay "cool" until I get in the water.

bring a 40 cuft (air) cylinder with a cheap primary and a schrader connector, fill suit and purge as needed.

 

[iamjblevine]

I'm especially interested to hear the experience of people with a range of wetsuits.

I dive in the Great Lakes Area in a 6.5mm Farmer John, 7mm Hood, 3 or 5 mm gloves, 7mm boots April to November. The bottom temps at one local inland lake at 85 ft was 42 in August. Is it cold? Yes. But it is tolerable. I dove 130' Wrecks in Lake Superior a couple weeks ago and was just fine. I've never had the disappointment of my suit flooding like the guys I dive with who dive dry.
Last November I was diving with two other guys who were in dry suits. I was fine all through the dive. I "Preflooded" my wet suit with a thermos of warm water before entry. The other two were chilly at the end of the dive. Back on shore, as we removed gear the story flip flopped. They dry guys were warm and toasty as soon as they got out of the water. I had to towel off before I could start to warm up.
Unless I start getting into technical diving with some serious deco obligations, I don't see myself investing in a dry suit for some time.

 

[fnfalman]

How do I keep warm? By constantly finning and sculling.

 

[TotDoc]

Do you find the thicker wetsuit or wearing extra layers under a suit makes a lot of difference in keeping you warm? For those who dive in cold water temperatures, which is better, a thick well fitting wetsuit or a drysuit? Does putting extra layers on under the drysuit make much difference.

Layers absolutely help, but at some point, all the extra layers just become extra bulk and start to limit your maneuverability. My girlfriend has a lavacore that she swears by. Its light, comfy, and doesn't require extra weight to sink. It also is apparently quite comfortable topside. Personally, all I like to layer is a hooded vest. Hoods are like adding an extra 2mm to your exposure suit - you lose a huge amount of heat through your head! A well fitting wetsuit that limits the amount of water in contact with your body is always better than a loose one, but it does not approach the comfort level of a drysuit.

Personally, if I need more than my 5mm and hood, I would much rather just wear a drysuit. Drysuits can be adjusted to any degree of cold water by changing what undergarments you are wearing. You can layer here, too, but again the limiting factor is how much the bulk affects your movement. There are some pretty advanced undergarments that help limit that, too, like the White's Thermal Fusion undergarment, which is pretty warm on its own. There are many companies that offer modular or layer friendly systems, too. But just to be clear - a drysuit can't be beat for keeping warm, and it's probably the best investment I have made in my diving.

Body heat is lost as it is travels directly through the neoprene. In the case of a wetsuit, heat is also lost by water flushing through the wetsuit. These two methods of heat loss are known respectively as heat loss by conduction and convection. The question is, how do you lose most of your body heat when diving - conduction or convection?

To clarify this a little, body heat is lost as it travels into the water surrounding you - about 20 times faster than it would be lost into surrounding air. The thickness of the neoprene you wear prevents this water from cooling down, which slows the overall process of you cooling too quickly. This is heat loss by conduction, and it is by FAR the way you lose the most heat underwater. If that water is flushed away (by a leak in your suit, or by pulling your neck seal for example), the heat was still technically lost by conduction.

Convection is still important, but plays a much less substantial role in diving. As you are moving through the water, heat moving through the neoprene of your suit is warming the water around the outside of your suit slightly. It's as THIS water is washed away and replaced with new cooler water that you having ongoing loss of heat by convection.

Understanding this also helps understand why a drysuit is so much better at keeping you warm than a wetsuit. Water is a much more efficient conductor of heat than air - about 20 times more effiecient, in fact. If you surround yourself with water, you will eventually become hypothermic - even in warm water, as long as the water is cooler than your core body temperature. In a drysuit, you are essentially creating a barrier of air - a poor conductor of heat - around your body. This allows you to significantly slow conductive heat loss, and greatly enhances your enjoyment of dives in colder temps