Sunday 24 February 2013

MYOG Quilt


When I decide I’m going to build a piece of kit I don't just try any copy what’s already out there. I sit and think about the problems of these designs and, more importantly, what it is I really want from a piece of kit. Quilts is an area I’ve been thinking about a lot recently.

This isn't a step by step guide to building a quilt but should show you enough to make something similar should you choose.



What I want from a quilt

Size - must be plenty wide enough to cover a restless side sleeper and also long enough to be pulled right up over my head when cold. Commercial quilts are often far too narrow for me.

Durability - materials, design and construction. Failure of my Z-Packs quilt was caused by the use of horizontal seams to join fabrics without leaving an adequate seam allowance. Obviously you are going to stretch in a quilt and that pulls against any horizontal seams. Looking at my PHD bags they all only had vertical seams which makes more sense to me. For a quilt that will be used for a minimum of 6 months in 12 then material selection should be light but not at the expense of durability.

Filling - down can last well but still looses loft over time and is difficult to wash. Do not believe the hype that says a down bag will last 20 yrs. It won’t if used continuously. Christine, who has been hiking full-time for longer than anybody else I know only gets, at most, 2 years from a down bag. I also wanted the option of adding extra down as the bag aged, or even completely replacing the filling without having to resort to the sewing machine. 

Washable - these can get pretty smelly quickly and need regular washing. Down quilts can be carefully hand-washed but you really need professional help to do it properly. If the filling could be removed then the shell could be frequently thrown in a domestic washing machine reducing the amount of expensive commercial washes.

Quilt, bag, blanket - they all have uses so lets make a quilt that can do it all.

Ventilation - being too hot is almost as bad as been cold. I wanted a quilt that can vent, particularly in the foot area.

Wearable - you will never wear clothing made from a quilt while actually hiking, or probably even at rest stops, but sitting around camp is another thing altogether. Here, a wearable quilt can be a very useful additional cold weather item of clothing.


Most of my list is easily accomplished and would already be available in a commercial custom built quilt. However, the option to remove, or replace, filling isn’t something I’ve ever seen done before so needed some thought. I came up with 2 ways this could be done.

Replaceable filling

The 1st, and lightest, is to add the filling directly into a shell and allow access to it via a down-proof access area. This access area would allow more down to be added as it aged, and lost loft, or it could easily be removed altogether for washing or replacement. Anybody thats ever worked with down knows that this isn't something you would do regularly as it’s very messy and gets absolute EVERYWHERE if disturbed. That said, a bag built this way could potentially last a very longtime and save a lot of money over its life with just the insulation being replaced every few years. It would be possible to add synthetic filling directly into the shell but to stuff each baffle would need a lot of filling and that would make a very heavy and bulky quilt.


The 2nd method is to use removable pods, or sausages as my friend Phil Tuner called them. These pods would be made from a light 10D nylon fabric and could be easily removed from the shell via a more simple access area. The advantage of this method is that washing or insulation replacement would be quick and mess free but those pods would add some extra weight to the quilt. You could have pods with different fillings and amount of insulation. For example on a high summer trip then I could reduce the down overstuffing amount down to 0 and save 30% off the weight of the filling, when it’s cold I might want 50% overstuff to guarantee full loft and to hold the down in place. Down, synthetic or, even better, a mixture of the 2 would also work in these pods. This could be useful if you want to use 1 bag in many different environments. Switching of pods would only take 5-10 minutes.

Weight wasn't going to be my number one concern when building this quilt - performance, durability and sizing were more important to me - but with a long hike across America coming up it was important enough that I wouldn't want to carry the extra 200g for a pod version. I went with the first option but decided to make the shell fully pod compatible for the future. Had I been going on a long cycle tour or kayaking trip then that weight wouldn't be so important and pods would have made more sense.


The Design

There are some good MYOG quilt kits available in either down or synthetic which could have been a starting point for this project. I decided to build my own from scratch as a quilt really isn't the most complex piece of kit to design. The first place I started with was how would you get access to the filling for replacement or topping up that would be down-proof but allow easy access. I came up with 2 options, a zip or a rollover closure like you would find in a drybag. A zip looked the simpler choice and I could never come up with a light and reliable way of securing a rollover closure system down the full length of the quilt. I normally keep away from zips because I find them to be weak spots in any piece of kit but as it is something that will only be used occasionally in a quilt it seemed ok to use one. A normal lightweight zip has a fairly open weave fabric tape strip that I wasn't at all certain would be down-proof so I chose to use a slightly heavier waterproof design. These zips have a coating of PU added to the fabric which makes it waterproof (ish!) but also, hopefully, down-proof. The zip is a locking type that once closed can’t be caught and operated accidentally, you need to lift the tab and pull to operate. To further protect the zip, and also help to stop it getting clogged up, a baffle would be fitted directly behind. The photo below shows the main baffles (cuben) attached to the zip baffle (pertex) and the zip loosely laid over to show how it will sit when attached to the shell.


This is the locking zip fitted and locked.


With access to the filling sorted it was onto the rest of the quilt. I wanted to be able to convert between a quilt, bag or blanket. 

Quilt/bag/blanket

A quilt or bag is preferable in a solo shelter where there isn't room for a blanket and also when you are expecting colder weather. Converting between the 2 is easy. A zip, as used in the Zpacks quilt, or straps, or press-studs would all work. The zip was soon discounted because it would be used all the time and risk of failure would be too great on a quilt that is being built to last many years of continuous use. Straps, I’ve used before and are standard fit on a lot of the narrower quilts. I find they restrict movement and I’ve never really got on with them. As my quilt will be plenty wide enough to easily go all the way around me then press-studs are the way to go. Very reliable, and if fitted every 30 cms you can fully seal up your quilt into a warmer, draft-free, bag when needed.


Converting to a blanket would be tougher because most quilts have a sealed foot-box area that does not allow them to be fully opened up. I like to have the option of a blanket when using hostels and also find them to be more comfortable in hot weather. My quilt would need an open foot-box which also brings us nicely onto the next option...


Ventilation

Overheating can be almost as bad as being too cold. This is one reason why I’m sold on the quilt idea, ventilating is much easier than with most bags. My cycle tour around Tasmania was a good example of the need for this. Most of the time, particularly around the coast, I was way too hot with my 0C rated quilt but when passing through the higher mountain sections I was only just warm enough. I can’t change quilts for each stage so the best option is to ventilate more. Opening up the quilt helps but the one area that is hard to vent is the foot. Sure, you can remove your feet from the foot-box but I still find it hard to get the balance just right. Having the option of an open end to the quilt would allow the foot area to vent in hot weather but if it had a drawcord, and an insulated plug, then the ventilation could be controlled from none (plug fitted and max warmth), to 100% (plug removed and drawcord fully open) and anywhere in-between. Another advantage of using a plug rather than building a foot-box is with the construction. A plug is very easy to build, a good foot-box is much harder. The only problem with a plug is making sure you get a draft free seal for when you need maximum warmth.


Foot-box

When the quilt was built and stuffed I decided not to bother building a plug until I had tested it “as is”. I found that the seam that allows the quilt to separate was naturally covered by the inner loft of the quilt and that only a small hole in the bottom of the quilt remained when the drawcord was tightened. I could have built a plug for that but I decided to do what I’ve done with The Z-Packs quilt and that was to stuff an item of clothing down into the foot area to seal. I will test and assess the need for a plug before going on the PCT in May.


Wearable

I like to sit in the evening and watch the world go by. Often it’s too chilly to do for long so I wanted to be able to wear the quilt around camp when doing very simple chores. This quilt was not going to have a hood and arms like this fantastic design - I really want to build one of these! In bag mode, and because the bottom of the quilt is open, it is possible to pull up the base of the bag and fastened the drawcord around the waist so that you can walk around camp. The top of the bag can be secured under the arms with the upper drawcord. When sitting outside the bottom can be secured around the ankles. Not the most elegant of wearable quilts but it is warm and still useful.

And no I’m not putting up a picture of me wearing the quilt!

Sizing

I have a selection of bags/quilts and took my measurements from the one that fitted best. 

Materials

My quilt was to be built to last but still be as light as possible. Weight certainly wasn't my number one concern and that is reflected in my choice of design and materials. I wanted my quilt to be able to survive numerous washes and years of repeated stuffing into storage sacks. It also needed to be tough enough to survive being worn around camp. I choose to use Pertex Quantum for the shell because a) I had some, b) it’s a tough 20D fabric that is well proven in outdoor gear.


The choice of material for the baffles was harder. Most quilts use a fine mesh and this is a cheap and easy to use material. Problem is that it catches feathers in the mesh so would make removing the filling harder. I also wanted to use a slippery baffle fabric so that pods, should I choose to use them, would be easier to fit (they would need to be slid in). My original plan was to use more Pertex Quantum but that’s a material that needs a lot of preparation if you are to prevent it fraying and failing. The other option was to do what Z-Packs had done and use Cuben Fibre. This was slippery enough for pods but strong and didn't need any preparation. This sounded a good option but I chose to use a heavier 0.75oz version instead of the 0.34oz Cuben Z-Packs use. Again putting durability above weight.


The highest quality down I could find came from Thru-Hiker.com and I ordered 400g.

Temperature rating

I wanted my quilt to keep me warm, as a cold sleeper, down to 0C without wearing additional clothing. From experience I knew I needed to be looking at a quilt rated for around -6C. Finding what baffle height to use and how much filling to put in the quilt required some work on google. I had been happy with the rating of my Z-Packs quilt so used the table shown here for baffle height. I played safe and went with the -7C shown in the table and used a baffle height of 5.6cm. Baffle width would be 12.7cm, also as per my Z-Packs quilt which was wide enough to insert my hand right into the baffle for stuffing. To allow for lose of loft of the down over time and to hold the down in place then the quilt will be overstuffed by 30%, again as is the Z-Packs.

The calculations I used for working out the amount of fill to put in each baffle are -

I’ve done all the calculations in imperial because it’s easier that way and then converted the final figure to grams.

Baffle height = 2.25”
Baffle width = 5”
Baffle length = depends on baffle section of quilt but 57” in the example shown
Fillpower of down = 900
Oversuff amount = 30%

Overstuffed Baffle Height (theoretical) = Baffle Height*Overstuffing amount
                                                         = 2.25*30%
                                                          = 2.925”
Baffle Volume = ((Baffle Length*Baffle Width)*Overstuffed Baffle Height)
                       = ((57*5)*2.925)
                       = 833.625
Amount of down needed = Baffle Volume/Fillpower of down
                                     = 833.625/900
                                     = 0.926oz
Convert that to grams = 0.926/0.035274
                               = 26g

Rather than do this manually for each baffle I made up a spreadsheet that did the calculations and conversions automatically. If you would like a copy then please ask and I will email it on.


Searching the internet there are quite a few options for getting down into quilts without the down escaping and going everywhere. I found options ranging from simply stuffing by hand to using a vacuum cleaner, yes really! I just stuffed very slowly by hand and had little mess. To measure the quantity of down I sat the plastic bag, that the down arrived in, on my scales and zero’d them and took out handfuls of down and stuffed it in each baffle as far as possible until the scales indicated that I had added enough. This didn’t prove to be that accurate and the bag ended up with 40g more down than I had intended. I didn't remove any of the overfill and left it with additional overstuff. 


Conclusion

I hadn't made a quilt from scratch before but it really was quite an easy task. If you are patient, know some basic stitches and can sew straight lines then you can build a quilt. Mine came in at 690g and I’m very pleased with the results. I have a warm 3 season quilt that fits me properly and that can be fully closed up into a bag when it’s really cold. It can be worn around camp or totally opened up for ventilation and is also built to last. Replaceable filling might not be something everybody would want, or need, but gear doesn't last long when used continuously and it should save me a lot of time and money. This is all great but the biggest bonus of MYOG is the pleasure you get from actually using it. 

And that is priceless.