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Originally Posted by
ukarcher
BillyBob, thats a lot of cerebral candy to consume.
It throws up a lot of questions.
Forgive me if i wobble on.You probably considered all this years ago.
below, though its probably the wrong terminology, i will use the expression 'dew-point'to indicate the point when vapor condenses.
Many of the people I've dived with, came out wet. Sometimes it was through leakage, but other peoples t.shirts looked exactly like they had just been for a run. I totally agree about the 'moisture shut off switch' I think it works better/worse in different parts of the body.
e.g. I think hands are much better at regulating themselves than feet.
Curious, were they still warm, even though at least somewhat wet?
Also wondering: do you guys, while diving in drysuits, ever get hot enough to sweat?
Is there a "wetsuit"? if so, what is the difference?
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considering the drysuit.... we have body, fleece, VBL(drysuit), then cold water. Even though the water is cold, there is not a big enough temperature change to induce the vapor to condense.
But, if it was condensing- or even if not - I'm thinking once a certain humidity ( as always if NOT overheating and sweating) is reached, the body will stop producing vapor at the skin, vapor which might then condense? And probably at this point there won't be enough moisture to interfere with the insulation of the fleece? So you stay warm enough? I have absolutely no knowlege, other than what has been discussed here - of how dry suites work. In fact, I have always been curious about that.
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thought...the VBL micro-climate only works if you seperate it from the dew-point by using warm insulation. So, if we had no top quilt, then the warm vbl would be in direct contact with the cold air, causing an immediate dew-point, condensing the vapor to water, and collapsing the micro-climate.
Agreed! But, back from the oceans to the hammock, any insulation I have on the skin side of the VB will be very thin and minimal, to be sacrificed as far as insulation goes, more or less. It is only to make the VB feel better by not being in contact with my skin. But once again, even if the dew point is reached, the humidity is ( hopefully ) high enough that the body stops production of more vapor, so you only get so wet, and the wet can't evaporate ( so no evil evaporative cooling) and can't get into your real insulation. But going back to the dry suit example, it might be that with wool and synthetic insulations, if it only gets a little wet before the "vapor production switch" is turned off, maybe there will actually be even a hint of insulation still available from that next to skin layer. I just don't know!
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With a cold drink on a warm day, we get condensation of moisture from the warm air on the outside of the can/bottle.
tin foil wrapped around an ice-cube in a warm room will collect moisture on the outside. I believe this is not from the melting ice-cube, but from the moisture in the warm air condensing at the dew-point on the foil. If we put insulation between the ice and the tin foil, there will be no condensation on the tin foil.
I would venture to say that wearing a VBL at room temperature should not cause wetness, unless you overheat, as there is no dew-point to condense the vapor inside into water.
Sounds good to me UK, as good a bunch of theories as any other! I'm not enough of a scientist to be holding forth on this stuff. ( And yet I am any way, right? :rolleyes: )
But we are about to get what should be the final word, from extensive in the field testing of VB clothing by one of our own, Fronkey! The theories make for interesting conversation. But I can't wait to see the real world results, whether good or bad, the pros and cons!