wetsuits and wool

[JimC]

There are three mechanisms for heat transfer - conduction, convection, and radiation. The sun is an excellent example of radiation as heat transfer - so is a typical industrial furnace. Conduction is dependent on contact between surfaces of objects. Convection depends on fluid flow patterns, and is the only method dependant on fluids. A 'woolly' insulation layer restricts fluid movement and therefore heat transfer via conduction - whether it's home attic insulation, a blanket on your bed, or wool inside a coat liner. That's why good insulation is very fibrous - it restricts the mean free path for any fluid current before distrubing the flow.

A wetsuit, if properly fitting, lets a thin layer of water inside between the skin and inner wetsuit surface, and then minimizes further flow of that water, minimizing heat transfer via convection. The wetsuit material itself helps minimize heat transfer via conduction, but in a fluid environment (whether air, water, or other fluid) convection is usually the predominant mode heat transfer is accomplished.

Hope this helps!

All true. I would sugest that conduction is the primary means of heat loss underwater has 23 times the thermal conductivitie of air.

A better fitting suit would likely go further to reduce convection than a wool lineing by my thinking aswell.

 

[jonnythan]

As others have suggested, these suits are well made and do a good job of keeping you warm through smart use of bare neoprene sealing and helping eliminate water transfer, almost like a semi-dry.

The wool is counterproductive, though.

 

[jonnythan]

Merino wool is particularly known for its insulating properties and durability, the Merino sheep is particularly well adapted to cold wet high country weather, so there must be something in it.

Merino woll does nothing more than cotton does when fully immersed in water. Just FYI.

 

[hurleyskis]

Merino woll does nothing more than cotton does when fully immersed in water. Just FYI.

I would guess that since wool insulates when wet that having a layer in the wetsuit would increase the overall insulation (even if it's minor). I've worn light weight wool longsleeve shirts under my wetsuit and it is definately warmer than without???

My $0.02

 

[jonnythan]

Wool insulates when wet *out of the water* because of trapped air spaces. The air trapped in the wool is what insulates.

When it's totally soaking wet, it does nothing.

 

[Aquawookie]

The following search on ASK.COM - "exothermic wool" provides this link,

www.izwool.com/qualities-of-wool-2.htm

With the following information. (there are diagrams also but I'm afraid they do not copy/paste well).

Wool's Hygroscopic Ability

Endothermic and exothermic reactions of wool.
The wool fibre is a complex fibre. The outer structure is made up of several cuticle layers, these layers form scales that are impermeable to liquids, permeable for vapour.

A wool fibre is always in a dynamic equilibrium within the surrounding environment, constantly absorbing and desorbing moisture vapour as a process to maintain a set equilibrium. The equilibrium is set to create a "least energy state". This is a physical molecular make up that controls a chemical equilibrium between polar sites with in the wool fibre and moisture molecules or vapour in the surrounding environment. The "Least energy state" is set by nature/ the sheep to assist maintaining homeostasis.

Polar sites are distributed throughout the wool fibre and are responsible for chemically attracting moisture molecules and expelling them according to the surrounding air environment and do so to maintain the chemical equilibrium. Energy in the form of heat is released and taken up again as this process occurs. The process of absorbing and desorbing moisture vapour is known as "hygroscopic".

PLUS.....

When a water molecule is attracted to a polar site the molecule is slowed down and releases energy in the form of heat, an exothermic reaction and known as "Heat of sorption". This process is not linear, fig 1, the drier the wool fibre the more moisture it can attract and the more heat can be given off. As the internal polar regions become filled, the less heat is given off.. This feature is useful for the build up of heat during warm up exercise and the affect rapidly decreases as the fibre fills with moisture vapour
If the surrounding environment is becoming drier the polar regions will release the water molecules, they will take up energy and be released back out into the environment, an endothermic reaction. It will only release enough vapour to try and maintain the equilibrium. Important for warm down as the fibre cools with the body and not any more than necessary which can cause chills.
The wool fibre can absorb up to 35% of its weight in moisture vapour internally. The wool fibre usually maintains approximately 14 - 18% moisture depending on the surrounding environment.
In most cases our surrounding environment is constantly changing, hence so is the wool fibre in trying to maintain its chemical equilibrium. Essentially the wool fibre is never stable unless in a controlled atmosphere and so is in an "dynamic equilibrium", a constant state of change.

Wool has a natural ability to hold moisture vapour within and between the fibres whereas synthetics will only hold liquid either within OR between the fibres. A synthetic product that is designed to hold moisture within the fibre is acting in the same manner as a sponge and as such has no ability to release the liquid unless it is physically forced to do so.

END

 

[MookieMoose]

The following search on ASK.COM - "exothermic wool" provides this link,

www.izwool.com/qualities-of-wool-2.htm

With the following information. (there are diagrams also but I'm afraid they do not copy/paste well).

Wool's Hygroscopic Ability


This is interesting, but agains is one of those things that only works in air, not underwater. The article itself says that the wool is "impermeable to liquids, permeable for vapour." Since there's a whole lot of liquid water, and not so much water vapour available when diving, any exothermic benefit from the wool absorbing water vapour is not going to take place when diving. Once again, marketing fails to measure up in the real world.

Cam

 

[miketsp]

With the following information. (there are diagrams also but I'm afraid they do not copy/paste well).

off subject, but just a tip, normally right clicking an image on a web page will let you save a jpg to your local drive and then you just attach it to the post.
OK back to normal traffic.

 

[Aquawookie]

This is interesting, but agains is one of those things that only works in air, not underwater. The article itself says that the wool is "impermeable to liquids, permeable for vapour." Since there's a whole lot of liquid water, and not so much water vapour available when diving, any exothermic benefit from the wool absorbing water vapour is not going to take place when diving. Once again, marketing fails to measure up in the real world.
Cam

I'm sorry but this statement is not accurate.

In the dynamic system which is a diver, water and a wet suit, water vapor is constantly being created from the heat source which is the diver. This heat/energy allows water molecules to disassociate from the main body of water but will quickly be condensed back to liquid form if there is no where else for the water molecule to go.

In this case there is a location for the water molecule to lodge, within the fiber of a wool strand. This would assure the wool will gather up as much water as it can hold in a short time.

The definition of a liquid is as follows,
A substance whose parts change their relative position on the slightest pressure, and therefore retain no definite form; any substance in the state of liquidity; a fluid that is not gaseous and has a definite volume independent, of the container in which it is held.

In this case, the water molecule is locked in place at the polar site and so is no longer considered to be a "LIQUID". The water molecule will not flow until the wool strand surrenders it up again. Water will not "flow" thru the fiber.

Or, to put it another way, a sodden sheep in a thunderstorm is not much different than a diver underwater. :11:

Baaahhhhh!!

Paul.

 

[DoItRite]

I have worked in two dive shops, each carrying a variety of suits. I have looked into the science of what really makes a suit work and yada, yada, yada.... but to me there is one thing that matters to me... comfort in the water. I have decided to rank the suits by their "warmth factor" in my opinion, having used each of these suits in dives of at least an hour in 68 degree water... I'll start with the "coldest"

- Normal Neoprene suit (scubapro s-tek, henderson 1 piece suits)
- Pinnacle non-wool suits
- Pinnacle wool suits (I'm guessing the prevention of water movement is what works)
- Henderson Hyperstretch (Not impressed other than fit)
- Bare Velocity "simi-dry" (comfortable and reasonably priced)
- Scubapro Everflex material (fits nicely, no "pilling", if properly fitted, allows virtually no water movement)

I will say that the store I currently work for is the Pinnacle dealer... so, I'm going against my business to endorse Scubapro and Bare suits. I will "leak" this info out for you guys... Pinnacle is working on their own "hyperstrech" which should be an improvement over scubapro's everflex (best on the market imho). Combine this with a merino lining, I think we may have a winner... but we will have to wait for DEMA to check it out.