Ultralight quilts

Discussion about making bushwalking-related equipment.

Ultralight quilts

Postby andrewa » Sun 16 Oct, 2011 10:25 pm

Just made my "ultimate" quilt shell, from 0.9oz fabric - 210cm long, 150cm wide at top, and 115cm at foot, with foot box as previously described. Shell weight 230g. Going to put 150g of 900 loft down in it, making total wt of 480g, which will prob be fine to 0c. There is only about 5m fabric in a shell, so even if you could get 0.5oz fabric, you'd only save 60g.
Time to start looking elsewhere for wt savings, I think, as I can't think how to reduce this one further.

Andrew At
Last edited by andrewa on Sat 22 Oct, 2011 4:24 pm, edited 1 time in total.
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Re: Ultralight quilts

Postby HitchHiking » Mon 17 Oct, 2011 8:01 am

Sounds great! Photos???
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Re: Ultralight quilts

Postby cams » Mon 17 Oct, 2011 9:26 am

Sounds good. So when are you going into production? ;) 60g is 25% of 230g which seems like a worthwhile weight saving (if you're trying to get the absolute lightest). Any place for some lightweight cuben fiber in the design? As baffles or something?

ps. did you mean 250g of down? Your total weight doesn't add up?
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Re: Ultralight quilts

Postby andrewa » Mon 17 Oct, 2011 11:50 am

Ha! There's an additional 100g weight saving immediately, without using lighter cloth! I am only going to put 150g of 900 in it.

A
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Re: Ultralight quilts

Postby Mark F » Mon 17 Oct, 2011 5:45 pm

Hi,

I am curious as to the conditions in which you plan to use your quilt. Using the size that you gave and the weight of the down (150g), after conversion I get a theoretical maximum fill of 4,760 cubic inches (this is usually discounted by 10% for the real world) and a surface area of the quilt of 4,280 square inches. This suggests you will get at best 1 inch of loft across the quilt. This should equate to a comfort level of 10-15 degrees Centigrade - 2" of loft seems to be needed on average to get to freezing. If you meant 250g of down then you get a theoretical loft of 1.85" and a temperature rating of around 5 degrees.

Experience is that the theoretical fill power of the down needs to be discounted by at least 10% in the real world so this would raise the temperature rating of the quilt. On my calcs you would need around 300g of down to get to freezing (270g theoretical + 10%). Of course you may be a warm sleeper, but I am willing to carry 50 or 60 grams more to ensure I get a warm night's sleep.

You also need to ensure that the baffle height in the bag matches or is slightly less than the required loft so that the down does not have extra volume to spread into and so leave cold spots.

As for the use of cuben in quilts, see http://enlightenedequipment.com/
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Re: Ultralight quilts

Postby Nuts » Mon 17 Oct, 2011 6:09 pm

Good one, some photos buidling it would be nice. I use a 45(F) 850fill down bag in summer, been ok to around zero with down jacket and duds. I'd like to build a cuben wateproofish bag/bivy, see how it works out.
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Re: Ultralight quilts

Postby andrewa » Mon 17 Oct, 2011 8:39 pm

Mark F,

I haven't calculated it out like you have. My prototype quilt, which I built a few weeks ago used ~250g of ~550 loft down and had an average measured loft of 4-6cm, albeit lightly filled, which is why I figure that 150g of 900 loft down would be similar fill.

More importantly, though, and I apologise for not making it clear in my initial comments, is that I sleep in all my clothes if needed - which includes Montbell thermawrap pants and Bozeman Mtn Works Cocoon Jkt (and will add recently aquired Montbell Ex-light down jkt to this), so I have a lot of added insulation if needed. I also carry a bivvy bag made from epic fabric, and have used this as an "inner sheet" when needed. Not sure whether this has any additonal vapour barrier effect.

Beyond this, I can post piccies of the shell, but, in my mind, until it's finished, it isn't that exciting! And, please don't enyone decide to make the same item and use it in the snow, and then get hypothermia. It is going to be part of my sleep system, which obviously involves a lot of other insulated gear.

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Re: Ultralight quilts

Postby Mark F » Mon 17 Oct, 2011 9:53 pm

Good luck with your quilt Andrew. One of the beauties of quilts is that you can easily add extra down so don't seal it up too well first off. I have worked with down quite a bit over the years (I used to manage a major manufacturer of sleeping bags) and have recently built my own quilt (Momentum 90 shell, 5cm baffles at 13cm spacing and 300g of thru-hiker 900 down) in my quest for lightness. I suspect that you got somewhat better down than the 550 rating suggests. This is not uncommon, it is just natural variability, but the down merchants and bag manufacturers describe the lower end of the fill power range to avoid problems. I believe this is not true for US sourced down described as 900 fill power as this really tends to be the top end of the scale (not much up side) and many US manufacturers use a different testing method which tends to a little more optimistic than the European test method.

Once you get around zero with a quilt the insulation value of your sleeping mat starts to come into play, so if you are getting good loft and are still a bit cool even with clothes consider upgrading the insulation of your sleeping pad. The standard NeoAir, or any mat with an R around 2.5, seems to be pushing its limit at around zero but I have just noticed there is now a NeoAir All Seasons with a R = 4.8 rating.
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Re: Ultralight quilts

Postby andrewa » Tue 18 Oct, 2011 6:37 am

Mark, that's basically what I have. My finished baffle size is 5cm, and quilt 150/115 x 200. I bought 300g of thru hiker 900 loft, and was hoping to use the residuum to make an understood for my hammock. Anyway, I need about 6cm loft for the quilt, so I'll fill it and see. It's not hard to add more down if it's a bit flat.

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Re: Ultralight quilts

Postby andrewa » Sat 22 Oct, 2011 3:46 pm

Finished quilt below -200g of 900 loft fill. Total weight 420g. 5cm loft (10cm for doubled quilt)
Finished quilt.jpg
Finished quilt.jpg (69.99 KiB) Viewed 2898 times
Finished quilt footbox.jpg
Finished quilt footbox.jpg (68.58 KiB) Viewed 2898 times
Loft.jpg
Loft of double thickness quilt
Loft.jpg (49.88 KiB) Viewed 2898 times
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Re: Ultralight quilts

Postby ofuros » Sun 23 Oct, 2011 6:01 am

looks good in blood red andrewa,
bet you can't wait to try it out !
Mountains view are good for my soul...& getting to them is good for my waistline !
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