This mini-review is part of Part 2 of our survey of airmats. We have a full-length down airmat (DAM) from Stephensons here. It does not seem to have a special name.
Stephensons Warmlite DAM
|Length||174 cm / 68.5 in|
|Width||56-41 cm / 22-16 inc|
|Thickness||10.0 cm / 3.9 in|
|Weight||673 g * / 23.7 oz|
|R-Value||5.5 - 15.5|
|Drag Force||13/13 N|
|Larger Side Tubes||Yes|
* The weight of 673 g (23.7 oz) includes the light stuff sack, as this doubles as a pump for the mat. A pity the stuff sack makes such a poor pump.
This is a fairly well-stuffed down airmat, or DAM. As such you would expect it to have a high R-value. Well, it does - period! What is interesting is that while the R-value does drop as the mat is squashed flat, it does not drop very fast. This is entirely consistent with the claim heard elsewhere that what matters with down is not solely the loft but the actual amount of down used. And this is consistent with the technical way down insulation works: what matters is the density of the tips of the finest down fibres. So, all other criticisms aside, this is one very warm airmat! It may be rather heavy, but it is warm!
The slipperiness is about intermediate in our collection of mats. The very high thickness makes things a little less stable, so you may need to take just a little care. If you could tie this mat to another it should be just fine.
Comments by Roger Caffin
This is a very thick full-length mummy-shaped down-filled airmat, or DAM. Down is sensitive to moisture from your breath, so you should use a pump to inflate it. A pump is provided, in the form of a very large stuff sack with a connector on the side. That is the yellow stuff sack on the mat in the first photo. The idea is that you connect the bag to the mat using this large connector, scoop up air in the bag, close it, squeeze it, and inflate the mat. The mechanism should be compared to the Mammut mat and the Exped DAM: they have integrated pumps inside the mat. The connectors on the yellow bag and the red mat are shown here.
The air inlet connector on the red mat contains a valve on the inside, so that once air has gone in it does not sail straight back out. The connector includes a plug to seal it. This plug is essential, as I found the mat lost about half its air over a couple of hours when there was no pressure on it. I would predict a very rapid deflation when you are lying on it if you do not use the sealing plug. That is probably normal for a valve of this nature: all it has to do is help you inflate the mat, not seal it long term. To deflate the mat deliberately you need to poke the inside bit of the valve inwards, to get it to release air. That's easy. Well, it is good that the plug is included, but the flap of blue fabric holding the plug looked very crude, and the sealing of the valve into the mat also looked a bit amateurish. Given how long Stephensons have been in business, I really was expecting a better finish than this.
Furthermore, the finish on the combined yellow stuff sack and pump bag was definitely unsatisfactory. For a start, the sewing was a bit rough, with the thread tension severely unbalanced. This can be seen in insert at the right side of the illustration, taken from the edge of the yellow fabric between the two connectors shown at the left. But worse, the sewing holes around the seams and around the connector on the stuff sack were large and I could feel a lot air blowing out of them while I was trying to pump the mat up. I felt I was getting only about half the air going into the mat, with the other half being wasted. You could of course seam-seal all the holes, to great advantage.
I have to say that, overall, this is a slightly odd mat. It looks conventional in shape and concept, but the finish is very 'hand-made.' That is not to say the mat won't work: it will, but for a company of this age the lack of a 'commercial finish' was unexpected. The edge around the mat is of course welded together, but the weld line is quite narrow, leaving two bits of fabric flapping around outside the weld. You can see that at the very left edge of the illustration. I would have thought welding near the edge of the fabric as well would have protected the inner weld and made it a bit more secure. But, it's functional, and holds air, which is what matters.
The next question is how easy would it be to use the supplied stuff sack to inflate the mat? Remember: the stuff sack is connected to the mat by the connector, so it can't be waved around very easily. Sadly, I have to report that I found getting any large amount of air into the stuff sack difficult. It is made from quite light nylon fabric, and it flops around. With a bit of practice I could get the stuff sack half full of air, then I could twist up the end to trap the air inside and squeeze the stuff sack. I seemed to lose a lot of air as I closed the top end of the stuff sack, and I could feel a lot of air blowing away from the region of the valve while I was squeezing, so only part of the air was going into the mat. Squeezing the stuff sack is not all that easy: I tried to stand it upright on the mat and use my body to press down on it, but doing so seemed to put pressure onto the valve bit of the connector from underneath, such that it was forced shut. I had to hold the connector/valve off the floor to get air to go in. Despite the very large pump bag provided, it took many, many pumpings to get the mat inflated. I was not happy with the whole exercise. You would really need a better pump than the stuff sack.
After all those surprises, does the mat itself work? Oh yes, and it is quite comfortable and very warm to sleep on too. I could overlook the rather amateur finish fairly easily if the pump worked reasonably well. The weight is quite reasonable for a full-length DAM, and it is very thick. However, after watching me struggle with the pump bag, Sue declined to be bothered trying to pump it up herself. This is relevant as she is the one who looks after setting up the mats inside the tent in the evening, while I look after the tent and the tent guys etc. So the mat is very nice, but you might need to rebuild the pump bag yourself, or buy a pump from somewhere else (eg Exped).
This is a mini-review in the 2011 Lightweight Airmats State of the Market Report. The articles in this series are as follows (mini-reviews can be found in Part 2), and a subscription to our site is needed to read them.
- Part 1 covers the basics, testing methods, and lists all the mats in the survey.
- Part 2 examines the actual mats, and the performance of each mat tested.
Disclosure: The manufacturers provided these products to the author and/or Backpacking Light at no charge, and they are owned by the author/BPL. The author/Backpacking Light has no obligation to review these products under the terms of this agreement.