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9

Yes, the R-value will add of your different layers. If you wear layer A with R=5 and layer B with R=2.5, the overall insulation value will be R=7.5. To explain this a bit, we think of two layers or flat walls which interact only due to thermal conduction. This is just a model and in reality other effects will come in play. The Fourier Law for thermal ...


9

I have a self-inflating mat, and I think the foam serves three purposes. In order of importance: It sets the shape of the mat when inflated. Think of the foam as limiting how far the opposite walls of the mat can be in any one place. If you didn't have this, the mat would become more of a circular tube as it is inflated. For cushioning, the foam does ...


8

I think the reason for this difference in slipperiness is purely a factor of surface material. Most foam pads have a tacky surface finish. Inflatable pads, on the other hand, usually have a sturdy synthetic fabric as the surface. Fabric on fabric (sleeping bag on inflatable pad) will stick less than fabric on foam, unless the fabrics have been treated ...


2

I think it's not the material or fabric on the top it's more the shape of the pad. The most self inflatable pads are fully flat and even on top. The most other pads aren't flat because they have chambers. This gives a uneven surface of the pad. So my conclusion is: You have less friction with the inflatable flat pad because of the surface structure, even ...


2

At the risk of sounding like a grumpy old person it seems like EVERYTHING is slipperier than it used to be. I'm not sure if new stuff starts slippery and gets less so, or if things are now made more slippery. But I have bought a new tent, new sleeping pad and new sleeping bags this year and between them - I had better set up on 100& level ground. I used ...


2

According to wikipedia2 In calculating the R-value of a multi-layered installation, the R-values of the individual layers are added. I would imagine a slight diminishing return as the r-value is a laboratory measurement in ideal condition which is not quite the same as on the field (variable temperatures, moisture, air movement, etc.).


2

The foam inside the mat prevents heat loss through convection which would be the case with the air if there was nothing to prevent it moving. This forms part of the open cell vs closed cell argument for sleeping mats.


1

I don't know how robust the waterproof bottom of your bivy bag is, but with the bivy bags I know (which are predominantly some kind of mountaineering emergency equipment) I would not want to put the sleeping pad into them. The reason is simply, that bivy bags are designed to give a good weather insulation (primarily by being waterproof and windproof) while ...



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