Are Drysuit Undergarments really necessary?

[fstbttms]

I also have trouble comprehending the theory that drysuit undergarments keep you warm while you are wet! If there was any truth in this why even use a drysuit?

You stay warm because the garment wicks the moisture away from your skin. Are you bone dry? No. But dry enough to be relatively warm and comfortable. Emphasis on the word relatively. And since there is no new, cold water (or flow-through) entering the drysuit, you stay warm longer.

 

[tech3324]

Why couldn't you wear a wetsuit as your undergarment? Aside from a little restriction in my movement, they do a great job at keeping me warm, especially when I get wet. I'm not a drysuit diver yet, so there's probably something I'm missing here.

There have been threads on that very topic, here's the most recent http://www.scubaboard.com/forums/exposure-suits/360821-would-wetsuit-work-drysuit-undergarment.html

The answer seemed to be that the wetsuit would compress and lose insulation just like it would without the drysuit.

 

[guyelix]

A wetsuit has to be wet in order to insulate your body. A dry suit... well ,you can figure it out from here! )

 

[fstbttms]

A wetsuit has to be wet in order to insulate your body.

Seriously? Have you ever worn a wetsuit out of the water?

 

[4sak3n]

A wetsuit has to be wet in order to insulate your body. A dry suit... well ,you can figure it out from here! )

This is false. A wetsuit merely slows down the rate at which you lose heat to the water. If you are not wet you will lose heat even slower than if you were wet so the wetsuit will work regardless.

 

[dave4868]

I also have trouble comprehending the theory that drysuit undergarments keep you warm while you are wet! If there was any truth in this why even use a drysuit? Why not try ice diving with just that "magical fabric" that keeps you warm when soaking with ice water? Is it even possible? Or can the marketing gurus make us believe in whatever they would like us to believe?

There's good science behind most of the drysuit thermal protection strategies and materials. Heat transfer is reduced and warmth is retained, often very significantly. And, yes, some materials significantly reduce heat transfer even when flooded with water. Personal experience will convince you pretty quickly....

Here are some interesting references, starting first with one from Rubicon's invaluable collection of articles.

Rubicon Research Repository: Home

From Rubicon's collection, a very helpful overview of coldwater diving by the American Academy of Underwater Sciences (see especially the sections regarding exposure protection by Dick Long, page 29, and cold water diving by Steve Barsky, page 65):

http://www.si.edu/dive/pdfs/ProceedingsColdwaterDiving.pdf

Here's more interesting info on DUI's thermal strategies, including the properties of Thinsulate B:

http://www.dui-online.com/tech_insulation_strategies.htm

Thinsulate™ Insulation
[FONT=Verdana, Arial, Helvetica, sans-serif]Thinsulate™ Insulation is made of a polypropylene fiber that is 1/1000th the size of a human hair. Polypropylene is a modified wax. This type of insulation is the most efficient insulator known at this time (weight to warmth ratio). DUI uses 200gram and 400gram compression resistant Thinsulate™ Insulation sometimes known as Thinsulate™ Insulation Type B or Ultra. This type of Thinsulate™ Insulation is commonly used in footwear as it will retain its insulating value even under compression from someone standing on top of it. In addition, the fibers are matted together so closely that the natural resistance of wax to water prevents water from entering the insulation even if water did enter the suit. Unless there is strong pressure on the material from a serious suit squeeze, the water droplets will not touch one another and they cannot conduct heat. The body will have to heat the water in the suit, but as long as the water droplets remain trapped in the fibers and do not touch each other, they can not conduct heat away from the insulation. This characteristic makes Thinsulate™ Insulation a great choice.[/FONT]

Here's an interesting website about diving under the Antarctic and the insulation needed:

http://peterbrueggeman.com/nsf/diving/index3.html

As to your original question in this thread, I use layers of polypropylene fleece outdoorwear as drysuit undergarments for water temps down to the low 40's. Fleece isn't as efficient as other fibers, so I need more of it and therefore need more weight. It works well for me.

For water temps below that, I use a Weezle Extreme Plus undergarment. I combine it with various other materials and techniques to achieve excellent thermal protection. One cold area, such as chest, head, hands, feet or face, can really reduce overall effectiveness, so I've addressed each one. My present method keeps me comfortable for over 90 minutes in near-freezing water temps.

The point is that you'll find there are many different ways to reduce thermal loss, some more effective than others. They will make perfect sense when you finally find yourself staying toasty warm on a long dive in ice water!

Dave C

 

[evil_xander]

I am thinking why do we forget this basic rule when it comes to drysuits? How can we put all our faith on a single layered jump-suit which no Arctic explorer or winter sport enthusiast would ever trust.

I also have trouble comprehending the theory that drysuit undergarments keep you warm while you are wet! If there was any truth in this why even use a drysuit? Why not try ice diving with just that "magical fabric" that keeps you warm when soaking with ice water? Is it even possible? Or can the marketing gurus make us believe in whatever they would like us to believe?

Flexibility of movement. Add more layers, lose more of the same.

For the second part, I believe if you stop pushing the envelope to the extreme side of the term 'wet', you might understand what everybody is trying to say. But it seems like you deliberately decide against doing so, so whatever keeps you happy...

The best you can do to fully appreciate the answers given to you are:
- start dry suit diving and get some experience using different underwear to judge for yourself;
- flood it once, or get a whole on the seal to see what happens with different types of underwear and how they behave

Or, just accept what others have already done and follow the given advice.

Learning to dive online is a SOB sometimes.

 

[CAPTAIN SINBAD]

Or, just accept what others have already done and follow the given advice.

There are people on both sides of the argument. Saxplayer has, in my opinion, presented an extremely valid argument as to why drysuit jumpsuits are not the optimum way of ensuring warmth. Dave4868 has given some very good research as to why SOME drysuit undergarments may be useful in case of flooding. There is no Me VS Others ping-pong going on here. I am grateful to both camps for presenting very valid points.

 

[tbone1004]

The flooding argument is in with the compression argument. You want to design something that wicks well not just in case of flooding but in case of sweating as well. Any of the cave divers know that you can't dive in a Drysuit in NFL without sweating. It just won't happen. Unfortunately that sweat does it's job too well in the water, and unless you can get it off of your skin you'll get chilled. Some of us sweat more than others, so for me if I'm in my suit and undies for too long at the surface I may as well have gotten a small leak in my suit. My undies wick very well and put the bulk of the water in the outer layer and keep the inner layer dry. Doesn't work quite so well as an insulator since there is no where for the liquid to go, but it does a lot better than down and fluffy stuff. Wool works similarly, it doesn't matter if it's wet or not, it insulates the same from a fiber standpoint, but the liquid sucks more heat out of you

 

[AfterDark]

I just bought a new Pinnacle BlackIce compressed neoprene dry suit. I’ve yet to use it, 1st I was sick now the weather is awful. My experience comes from diving with the older neoprene suits like the UniSuit or JetSuit, these suits had insulating qualities of their own so the undergarments could be less. I found that a light polypropylene wicking undergarment covered with, a sweat suit, a ski suit or some other similar garment for warmth worked well for me. So well in fact I could use wet suit gloves and my hands stayed warm. I’m going to try the polypropylene wicking undergarment under ski pants and a Thinsulate M65 field jacket liner this Saturday for the first dive of 2011. I’ll report my experience after the dive.