Re: Hammock Camping Re: Oh Boy, Cold Wars II, winding up!
- At 03:49 AM 9/3/2003 +0000, you wrote:
>Therefore, if the insulation is down, and if the wind is strongThis is where you are making your mistaken assumption. Your insulation will
>enough to have the temperature halfway through the down be similar to
>what it is outside of the down, then you have lost half of the
>insulating value of the down. If the insulation is closed cell foam,
>and the wind is strong enough to have the temperature halfway through
>the closed cell foam be similar to what it is outside of the closed
>cell foam, then you have lost half of the insulating value of the
>closed cell foam.
>And if in either case you place a wind-proof layer outside of the
>insulation then you will regain the half of the insulating value that
>had been lost to the wind.
continue radiating heat into the air which will be lost to convection when
the wind blows away that warmed air.
The wind is not blowing in beyond the boundary layer of your closed cell
pad. The pad is losing heat through conduction to the colder outer
layer.but if you can keep the wind from blowing away that boundary layer of
warmed air, your insulation will remain warmer.
Adding a wind-proof layer right on the outside of a wind proof closed cell
pad will only gain you the insulation value of the outer broken cells and
the insulative value of the barrier. the layer of air on the other side
will still will still have convective heat loss from the wind moving away
the warmed air.
> >The goal of your windproofing efforts should be to keep the wind asStagnant air IS insulation. That wind is blowing away your insulation.
> >far from your insulation as possible, not just to keep it out of
> >your insulation. The advantage to the skirt and cone ideas is that
> >they protect the outer air layer of your heat bubble.
>Because of convection if doesn't matter how far away you keep the
>cold wind as long as you have the same thickness of the same
>insulation in the area protected from the wind.
>Again, this is an approximation.
> >As for the condensation issues... You need convection, but theYou are limiting your thinking here. If you need a source of cool dry air
> >source of the air does not necessarily have to come through the
> >From what I have read about the "chimney effect" and tent design it
>is necessary to a have a source of cool dry air below and a vent
>above where the warm moist air can exit.
>I was hoping to find that if was possible to have a windproof hammock
>with a large open area above and avoid the condensation problem. It
>appears that this only works if the hammock is somewhat windproof.
>Therefore it appears that fresh air must come from below and through
>the fabric of the hammock.
below, it does not require that the material directly under you breath. You
could experiment with vents in the bed of the hammock, or any other low
entry. A breathable bed is just the easiest to implement.