In Part 1 of this series we discussed airmats in general, outlining the properties we thought important, how we could measure some of them and assess others, and, finally, we listed all the mats being tested in a table. To recapitulate, our criteria for inclusion were that they must weigh less than 400 grams (14 oz) for summer use and 800 grams (28 oz) for winter use. We also looked at what benefit might be had from combining a very light airmat with a very light foam mat. There turned out to be a surprising range of airmats meeting our criteria (see that photo there!).
We have assessed the mats both in the laboratory and in the field for the following properties. In this case 'we' includes not just us authors, but also our wives - whom we thank for their assistance.
We have a Summary near the end of this article which covers the full range of points we found, without focusing on actual models. It is followed by a table of measured performance results.
Points of Interest
- R-value - if the bed you are lying on is cold, not much else matters. In this case, cold is cold. We find novices complaining regularly about being cold while using a very good quilt or bag due to this problem. However, we found that the R-value depended on the thickness of the airmat, so we have measured every mat at a wide range of thicknesses, from fully inflated to 'hips nearly touching the ground.'
- Dimensions - length, width, and thickness. Some mats were supplied full-length, while other were 3/4-length, 2/3-length, or even shorter. This complicated things slightly, but not badly.
- Weight - a high priority at Backpacking Light: see our criteria as listed above.
- Stability - allied to comfort, but it includes things like the slipperiness of the mat under you and the shape of the tubes making up the airmat. Some mats can leave you rolling off the sides too easily; others feature larger tubes at the edges to prevent this.
- Ease of inflation - some mats self-inflate, while other require sustained blowing from an exhausted walker whose head starts to spin. A recent development has been air mats with down or synthetic insulation with in-built lightweight pumps. The pump means you are not blowing moisture into the down inside (or making your head spin).
- Outline - the shape of the mat. Typically, some mats are rectangular while others are tapered or mummy-shaped. We have two distinct needs here: the mummy shaped and tapered mats are fractionally lighter, but they are a real pain for couples as the mats can leave big gaps between the sleepers.
- Packed volume - a rather low priority item as it is weight, not volume, which really matters on your back. Also, we found that packed volume varies significantly, depending on how much effort was put into squeezing all the air out.
- Noise - not normally of concern to solo sleepers who can tolerate their own noises, but definitely of concern to couples when one wriggles more than the other. Some mats were more noisy than others ...
We discuss some measured properties here; the rest are more subjective and will be discussed in the mini-reviews of each mat. The full data set is at the end of this article; in between we discuss different ways of looking at the data.
- Points of Interest
- Laboratory Assessment
- R-value and Tested Thickness
- Further Caveats about the Testing
- Effect of Adding Internal Insulation
- Effect of Compression on Filled Air Mats
- Comparative R-values
- Field Testing
- Summary, and Opinions
- Self-Inflating Foam Mats
- Plain Air Core Inflated Mats
- Synthetic Insulated Air Core Mats
- Structurally Insulated Air Core Mats
- Down-filled Airmats (DAMs)
- Foam Overlay
- Air Pumps
- Surface Friction
- Future Trends (We Hope)
- The Mats Tested
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