Question Building a cold water undersuit/undergarment system.

[Bald Wookie]

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.


Are you saying wool is great for drysuit undergarment?

I suggest crushed as you don’t have as much of a buoyancy swing when at depth. Compressed is also a good option. My 6mm neoprene is great, lovely and warm, but I’m also wearing 34lbs and a steel tank.

I suggest wool as an inexpensive option for some. Wool can be good, but undergarments designed for diving are typically better. I use a Marino wool base layer and an older DUI onesie over the top. So similar to what I have suggested, I just haven’t had the need personally to upgrade to the xerotherms (or similar, brand aside) as I have a decent cold tolerance thanks to the toasty Canadian (Newfoundland and BC) waters I now call home.

 

[Erik H]

Many great and useful comments here. Thanks everyone. I feel that I need to clarify some things and add some information.

Crush neos are much better for cold water diving. Even a 2 mm crush is significantly warmer than a trilam.

I know that neoprene is warmer, but I have a weird preference towards trilaminate suits. Deep down I feel that trilaminate drysuits are cooler and more “high-tech” and performance oriented. I also like made-to-measure suits and a more form fitting “cave cut” fits as I am broad shouldered and narrow waisted, therefore most garments that aren’t “form fitting” sit baggy on me. And I do realize that neoprene suits have a more fitted and streamlined fit. I am just not a fan of the increase in buoyance you can get as you ascend in neoprene as it decompresses and becomes more buoyant unlike what with trilaminate suits. I also dislike that you apparently need more weight when using neoprene than you do with trilaminate. I know some undersuits and undergarments compress and expand with changing depths and pressures, but I am thinking of and looking for incompressible garments and undersuits. I had completely forgotten about crushed neoprene.

Mixing wool with anything as you do now is a bad idea. No wonder you're getting cold with wool under your drysuit.

I use Merino Wool for socks and base layers as I’ve understood it is sweat wicking as well as insulating even when wet. Otherwise, I have a mix of fleece shirts, sweatshirts, and pants.

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.

It’s hard to say where the threshold is that my hands and feet start to really freeze during a dive. I can say that I ALWAYS walk around with my hands in my jacket/pants pockets to keep them warm, even during warmer weather. As for my feet, I really notice when standing still slightly chilly conditions. I suspect I have generally bad circulation to my extremities.

I completely agree that a warm enough undersuit/undergarment set needs to be just warm enough/tolerable before even thinking about electric heating. I would rather not be too chilly and have the heating to get to a more comfortable temperature especially towards the middle/end of the dive.

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.

I’ve thought it more logical to get the undergarment system first, and THEN getting the right size/fit of a drysuit to fit your thickest undersuit setup, but maybe I’m wrong. I’ve looked at some made-to-measure instructions that suggest you have your undersuit on while you get measured (Seal SL:01 for example). Just seems counterintuitive to get to drysuit first and then the undersuit if you don’t know how thick the undersuit/undergarment setup might be.

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.

I do use a 7mm hood and must use at least some glove liners with dry gloves. I have some very warm and thick gloves, but I hate not being able to feel what I’m doing with my fingers with such thick gloves, hence wanting heated gloves/liners that are thinner. For socks I use two layers of Merino Wool and sports socks, while the boots have been attached tech boots that were slightly oversized due to the suit being a rental.

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.

I’m getting a feeling that neoprene might be what I need, but I still like the idea of more flexibility and mobility with thinner trilaminate materials compared to stiffer and thicker neoprene. You are all starting to make me seriously think about neoprene though.


Keep the great advice and suggestions coming!

 

[berndo]

Trilaminat suits don't really give you more flexibility or mobility than crush neos. Most important thing for mobility is that the suit fits properly.
Old drysuits made from normal 6 or 7 mm neopren are nothing like the crush neos you can buy today. All the stories about the disadvantages and buoyancy issues of neos are probably from the times when people still used those old 7mm drysuits.

 

[Bald Wookie]

You can really pick either way, suit first or undergarment first. Depends on what the requirements for measuring for your suit are, as they change from manufacturer to manufacturer.

A 1mm or 2mm crushed neo has great flexibility, like Berndo has said. No buoyancy issues like with the non-compressed neoprene. Plus its warmer. There are a few places that will custom cut a neoprene suit for you. You've said that you're doing recreational but I'm guessing you are planning some tech stuff in the future if you're looking at cave cuts? Really, it just means it fits you well and you can reach your valves on a BM Doubles setup.

For gloves - I use one thin layer on the bottom, and have some fingerless gloves for the majority of the hand warmth and excellent flexibility. I don't mind the tips of my fingers being slightly cold, in fact I barely notice at all. Air flow into my hands from the suit has really been the biggest source of my cold hands. I forgot to put something under my wrist seals the last couple of dives and could not get my gloves to equalize at all, so my hands were crushed and quite cold.

For socks - sounds like you're on the right track, a thin layer and then a thick set over the top.

Fleece isn't the greatest material for drysuit warmth, but its far from the worst. You'll notice a big difference when you get a good setup

Again, I'm diving in 5*C water in BC, and zero degree in Newfoundland. In my experience the majority of recreational divers do not need heated undergarments until they start tech. And I don't think anyone here is warning you away from them for any reason, just keep in mind a good setup would let you dive without the expensive investment in a good electric setup.

 

[rjack321]

I would put aside any preconceived notions about what looks cooler. Crushed neoprene is going to be 1) warmer and 2) more durable and cut resistant - either wrecks or things like rusty nails in flooded mines like Tuna Hasberg.

I'm a fan of the weezle extreme+ undergarments and everyone I know who has one says its the warmest they've ever tried, plus more durable than the halo. Their booties are also top notch.

 

[mr_v]

@Erik H : You can solve most of your concerns with custom a suit.

First, get proper garments. Merino base is okay, but you ought to get undergarments that provide appropriate insulation while they're compressed.

Second, get fitted for a suit. Made to measure. Not "let's take your size and then figure out what fits." Straight up made-to-measure. If you want your suit to come out more roomy, put more undergarments on (that you don't plan to wear otherwise). If you want to a more tailored fit, wear your regular undergarments as you get measured. You do not want to wear thinner undergarments to hope for a tight fit - most made-to-measure suits will be snug!

Third, managing minor buoyancy changes is not a big deal. Ask CCR guys who have to deal with multiple volume management while ascending. If you dive enough, you'll react with proper adjustments in no time.

Finally, trilam dries faster and is lighter - good for travel. However, there is absolutely nothing wrong with neoprene. If you're really concerned about bulk weight, look into heated undergarments. You'll get heat minus the bulk.

 

[rjack321]

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?

The FE Halo AR has no actual argon gas in it. It has a gel based insulation. Argon is generally a waste of money for all but the most extreme dives and you need to flush your suit thoroughly

 

[Erik H]

Now I'm starting to understand the worth of a good modern neoprene drysuit for really cold temperature dives. Seems that crushed neoprene is the way to go (because it doesn’t have a shift in buoyancy as depth changes?). I’d definitely prefer made-to-measure/custom fit. Some have recommended SF-Tech, but any other recommendations for MTM crushed neo drysuits?

I’m kind of leaning towards FE undergarments but still unsure about a full undersuit. Heard a lot about Weezle but they seem like they are rather “fluffy” and likely require more weight to dive? Doesn’t seem like people recommend the Santi BZ400 or heated undersuits.

Still, a reason why I’m interested in trilam drysuits is due to their flexibility and versatility of use in different temperatures and environments.

 

[rjack321]

Now I'm starting to understand the worth of a good modern neoprene drysuit for really cold temperature dives. Seems that crushed neoprene is the way to go (because it doesn’t have a shift in buoyancy as depth changes?). I’d definitely prefer made-to-measure/custom fit. Some have recommended SF-Tech, but any other recommendations for MTM crushed neo drysuits?

I’m kind of leaning towards FE undergarments but still unsure about a full undersuit. Heard a lot about Weezle but they seem like they are rather “fluffy” and likely require more weight to dive? Doesn’t seem like people recommend the Santi BZ400 or heated undersuits.

Still, a reason why I’m interested in trilam drysuits is due to their flexibility and versatility of use in different temperatures and environments.

Crushed neoprene is basically stable and won't change buoyancy over the course of the dive. It's also the same R-value at the surface as at depth. Conventional neoprene is crushing and you'll have less buoyancy and more importantly less r-value in the suit at depth no matter how much gas you add. If you are a harvest diver or something collecting urchins or tending net pens in 15m of water the cost to value ratio plus the durability of a normal uncrushed neoprene suit is great. For everyone else not so much.

The BZ400 wears out fast - and is almost impossible to safely wash. And the heated version is actually so much heat that you tend to rely on the battery instead of insulation. So if the battery were to fail you're very underinsulated.

The weezle is fluffy and traps alot of air. That's the fundamental definition of insulation.

 

[rob.mwpropane]

I'm a fan of the weezle extreme+ undergarments and everyone I know who has one says its the warmest they've ever tried, plus more durable than the halo. Their booties are also top notch.

That's interesting. I've never seen a Weezle in person but from the videos it looks like it has the same type of material on the outside that all the other thinsalate type undergarments use. I would think the Halo would be be more durable? The Weezle (I would think) would be much easier to get into a suit.

I have a Halo 3D and think it's pretty robust and fairly warm. Easy to reach valves. About the only thing that has gotten cold while wearing it are my hands and my arms a little (but that was in 38F for ~ 70 min just very slowly going along). It seems that the arms have less material than my 4E Arctics, I have no idea why.

It's not hard to get into the suit, but it doesn't glide like other one pieces I've tried.