Question Building a cold water undersuit/undergarment system.

[Erik H]

I know this topic has been written about to death, but I can't find an existing thread that answers all of my questions and needs or talk about exposure suits for temperature ranges that I dive in.

I currently dive in Sweden where water temperatures regularly get down to 0°C winter season but might touch 22°C during the summer, but I'm more concerned about diving in the colder temperatures. Atm. I use a rental neo drysuit but would like to get a trilam very soon. However, my undergarment system right now is mixed layers of different materials like wool and fleece. Now, I am looking to build a true dedicated drysuit undersuit/undergarment system but have some preferences. I dive recreational with a single tank so dive times aren't all that long. Even then, I tend to be cold and easily freeze in my hands and feet (I always have cold hands and feet, even out of the water).

I'm looking to build a system with maximum warmth in mind but also with minimal bulk, to minimise extra weight requirements but keep good mobility. That's why I am thinking about electronically heated options like undersuits, vests, shirts and such. The thought is to have a thinner undersuit that can be electrically warmed up to be similar to a thicker undersuit. They may also be used together with a base/mid layer garment as well if needed. I know of quite a few brands that sell heated garments: Santi, SmartTex, Venture Heat, Thermalution, Heizteufel, etc. I also know of some heated gloves and a couple of heated socks by the same brands and have even thought of heated insoles, all for added warmth to the digits. Any thoughts and/or suggestions on the heated garment route? Santi BZ400, Flex 2 undersuit and Flex 2 vest are often named. I personally like the idea of the full undersuits for the heated arms and legs. Anybody with experience with them? Could the Flex 2 when heated (preferable as it is thinner) be as warm as the BZ400 unheated or equivalent undersuit? For gloves and socks, I'm partial to thinner materials to keep dexterity in the dry gloves.

Apart from heated garments, I also find the FE Halo AR interesting. Using argon to make a warm yet thing undersuit makes it really appealing. Anybody know how well they work? I realise I would have to use layers with this undersuit and would likely use FE or Waterproof layers. Any other suggestions for maximum warmth with minimal bulk?

Many Thanks

 

[grantctobin]

I know this topic has been written about to death, but I can't find an existing thread that answers all of my questions and needs or talk about exposure suits for temperature ranges that I dive in.

I currently dive in Sweden where water temperatures regularly get down to 0°C winter season but might touch 22°C during the summer, but I'm more concerned about diving in the colder temperatures. Atm. I use a rental neo drysuit but would like to get a trilam very soon. However, my undergarment system right now is mixed layers of different materials like wool and fleece. Now, I am looking to build a true dedicated drysuit undersuit/undergarment system but have some preferences. I dive recreational with a single tank so dive times aren't all that long. Even then, I tend to be cold and easily freeze in my hands and feet (I always have cold hands and feet, even out of the water).

I'm looking to build a system with maximum warmth in mind but also with minimal bulk, to minimise extra weight requirements but keep good mobility. That's why I am thinking about electronically heated options like undersuits, vests, shirts and such. The thought is to have a thinner undersuit that can be electrically warmed up to be similar to a thicker undersuit. They may also be used together with a base/mid layer garment as well if needed. I know of quite a few brands that sell heated garments: Santi, SmartTex, Venture Heat, Thermalution, Heizteufel, etc. I also know of some heated gloves and a couple of heated socks by the same brands and have even thought of heated insoles, all for added warmth to the digits. Any thoughts and/or suggestions on the heated garment route? Santi BZ400, Flex 2 undersuit and Flex 2 vest are often named. I personally like the idea of the full undersuits for the heated arms and legs. Anybody with experience with them? Could the Flex 2 when heated (preferable as it is thinner) be as warm as the BZ400 unheated or equivalent undersuit? For gloves and socks, I'm partial to thinner materials to keep dexterity in the dry gloves.

Apart from heated garments, I also find the FE Halo AR interesting. Using argon to make a warm yet thing undersuit makes it really appealing. Anybody know how well they work? I realise I would have to use layers with this undersuit and would likely use FE or Waterproof layers. Any other suggestions for maximum warmth with minimal bulk?

Many Thanks

Post in thread 'Bottoms of feet cold (drysuit, 39F / 3.9C water)'
Bottoms of feet cold (drysuit, 39F / 3.9C water)


There’s a pdf in post 3 that will answer many of your questions. Minimal bulk isn’t really an effective option in 0°C water.

 

[berndo]

I use a rental neo drysuit but would like to get a trilam very soon.

I wouldn't to that. Crush neos are much better for cold water diving. Even a 2 mm crush is significantly warmer than a trilam. Only donwside is that they don't pack as small.

And don't buy santi. BZ400 suits you can get from other brands for half the price. Like rofos.
I would get a bz400 and underwear you would use for skiing and go from there. Mixing wool with anything as you do now is a bad idea. No wonder you're getting cold with wool under your drysuit.

 

[MaxBottomtime]

I use a Waterproof D7X Nylotech drysuit, dry gloves, 10 mm hood, and a Weezle undergarment year-round. I've used the same set-up in the Galapagos as I have in Canada. I have a heated vest hanging in my closet that I haven't used in a few years.

 

[broncobowsher]

I will say that you will need to hold off on the heated stuff until after you own a suit.

What I have found after years of searching, undergarment vary drastically from person to person. Personal tolerance is a factor that prevents a good universal answer. 0°C is likely to add other limiting factors. At what point will you feet, hands, head be cold to the point that you call a dive, even if you manage to keep the body warm? And generally best to not put too much dependence on the electrical system. You need to survive if the heat fails. Maybe not the most comfortable, but tolerable. That takes real insulation, and that makes for bulk. Dense bulk is preferable over fluffy bulk.

 

[Bald Wookie]

I kind of agree with most of the above.
Pick your suit first. If you are sticking with recreational diving only, then maybe a neoprene suit is the way to go. More tech in mind in the future? Sure, a tri-lam is a great option for reaching valves etc. Maybe a thin (1-3mm) neoprene suit might also fit the bill, but make sure its crushed neoprene.

Once you have your suit, pick a set of undergarmets, make sure they fit you, and make sure they fit in your suit. A suitable diving undergarment resists some compression and keeps loft and warmth longer, so while picking out ideal fabrics like wool is a good start, if you get a squeeze they often don't loft back up to the level they were at the start of the dive, meaning you're colder.
My personal recommendation is two thin baselayer undergarments (pants and top, like the Fourth Element Xerotherm), and a thicker one piece undergarment over the top (Like the Fourth Element Arctic). Try these out for a dive or two, THEN consider adding electric heat. Grants guide is great. I use fourth element as an example here, but you get the idea. Many brands would suffice if they fit you well.
- Make sure your hands, feet, and head are also relatively warm. While it is important to keep your core warm, I've seen many people dive with thin hoods, thin socks, no undergloves (I'm assuming you're diving dry gloves but I probably shouldn't), and wonder why they're cold. A well fitting hood makes a huge difference, meaning water does not flow in and out of it for your head to re-heat it each time. Dry gloves should also get a tiny amount of air flow to reduce a squeeze and keep you warm. Boots should not be tied so tight they squash your feet and don't let air in there.
- Personally, I don't see the need for argon in diving unless MAYBE you're doing really long tech dives, and I don't quite believe the hype of argon in the layers. However, the Fourth Element argon system is quite thin compared to other similar undergarments and although I have personally not used it, my friends that have enjoy the warmth and flexibility that it gives. YMMV.
- This system is flexible and allows you to add/remove layers when its warm or cold.

Above all else, enjoy your diving and be safe.

 

[berndo]

If you are sticking with recreational diving only, then maybe a neoprene suit is the way to go. More tech in mind in the future? Sure, a tri-lam is a great option for reaching valves etc. Maybe a thin (1-3mm) neoprene suit might also fit the bill, but make sure its crushed neoprene.

This is an old wives tale perpetuated by DIR people who never used any crushed neo suit. You can move just as well in a crusher.
When you look at something like an SF-tech suit, their material feels like soft fabric but is super tough. And all their stuff is super popular amogst European cave divers and it's all compressed neo.

A suitable diving undergarment resists some compression and keeps loft and warmth longer, so while picking out ideal fabrics like wool is a good start, if you get a squeeze they often don't loft back up to the level they were at the start of the dive, meaning you're colder.

Are you saying wool is great for drysuit undergarment?

 

[grantctobin]

Are you saying wool is great for drysuit undergarment?

Have you heard of merino?

 

[berndo]

Have you heard of merino?

For the wicking layer as in ski underwear.

 

[mr_v]

I am in a similar boat although my local temps are slightly higher.

First, go with a crushed neo suit. Custom made suits (I mean full made-to-measure) with good crushed neoprene will give you the flexibility and the warmth you want. SF Tech is my choice.

Second, multiple layers. You can use athletic base layers, e.g., Icebreaker Merino. However, I find that synthetic layers are easier to do on and off. I used Under Armor compression stuff: UA Men's Baselayer

Third, invest in proper undergarments that maintain warmth while crushed. I love Fourth Element quality although I have yet to dive it in really cold water.

Fourth, maintain the core temperature first. Warm blood will circulate through the body and act as a heater. Proper socks and dry dry gloves will be mandatory in your environment.

Finally, as you progress in your diving journey, consider how hypothermia may affect you and whether that is a real danger. Hint: properly insulated divers are mostly okay in cold water but must maintain a correct body temp profile to avoid getting bend if deco is involved. Right now, there is a good chance that you don't need heated underwear.