I've been tempted to make a 25" wide air mattress that is between 36"-48" in length. Mostly because I'm not very excited about the idea of spending $150+ on a NeoAir or other mattress only to cut it. There is the Thermarest Trekker Large Torso. However at a 16 oz I think I can do better with a 30d top and 70d bottom. Using 30d baffles and a replacement Thermarest valve I've calculate 9-10oz. I have a friend with a few hobby irons for modeling and I would use the heat sealable fabric from Seattle Fabrics
http://www.seattlefabrics.com/nylons.html#heat sealable 30 Denier Ripstop
Questions:
Is insulation necessary for 3 season backpacking? Thinking from roughly freezing on up. If so down or apex?
If apex what weight and would you glue it to the top, the bottom, or both?
Is the 70d overkill?
Aquaseal or the glue that came with the valve?
Thanks in advance!

Synthetic insulation would be much easier to deal with. With down there are issues with migration and clogging the valve.

I'd bond it to top and bottom.

I believe Bender was using nanoseeum baffles.

Synthetic insulation would be much easier to deal with. With down there are issues with migration and clogging the valve.

I'd bond it to top and bottom.

I believe Bender was using nanoseeum baffles.

Eric,

MYOG air mattresses are easy to make IMO, just time consuming since not using an impulse sealer. I've made a handful of them and have learned a lot through trial and error.

For a 3-season pad I would use insulation for sure, and would also use synthetic. Easier to work with and no worries about down migration, plus not as much worry about taking a separate pad pump as with down...I personally think 70d is overkill, but everyone's camping habits are different. I've had no probs, but of course I am careful. Seems like I read somewhere that the puncture resistance of 70d over 30d is very little. Don't take that as the gospel though.

For me, the valve was always the trickiest part. I had spotty results with using the Thermarest replacement valve. It was always a chore to get it sealed consistently. I ended up using kite valves which work great, just not as clean looking. I would practice sealing your valve on a couple pillows first.

Don't forget to allow for the pad to "shrink" when you blow it up, even when using baffles. Similar to a quilt, your final measurements will be smaller than your initial measurements. Speaking of baffles, I would use the 30d material. Very little weight savings for the effort on a pad this short.

Ryan

This sounds very awesome, however I'm trying to get my head wrapped around this...

With Climashield Apex you wouldn't have to do baffles right? So basically you're gluing insulation on the nylon, heat sealing around the edge and then gluing in a kite valve?

Would you have to use a hobby iron or could you use a regular iron?

@Ryan - what type of glue for the valve?

I was wondering that same thing. In my mind, baffles in an air mattress serve two purposes:
1: To keep the shape of the air mattress. Keeping it flat through the midsection so it doesn't turn into a beach ball.
2: To limit air currents inside the pad. Limiting heat loss to convection. I could be wrong and maybe the basic vertical baffles don't have much of an effect

If you put in a synthetic insulation, it can't really migrate. So the only purpose of baffles would be #1. If so it seems like you could get away with 1" vertical strips at intervals. Something akin to a large inflatable mattress for house guests. I was planning on using McNett Aquaseal for any gluing.

In all honesty I had just considered doing the first one sans insulation and using a ccf, like evazote) pad to protect against punctures and boost the R-Value a little. I'm going on a quick 3-day trip in the Big Horns in a couple of weeks. I've used a POE Ether Compact 6 in the same location at the same time of year last year and didn't feel cold. Note, that I'm not a quilt user yet so there is a bit of something between me and the pad, (I know, not in the contact points).

NM

Edited by apthibault on 07/13/2012 11:03:37 MDT.