On most of my trips I and more so my down quilt got wet not so much because of rain but because of condensation: either condensation on the inside of the fly which ten dripped down on my quilt or because of condensation inside the quilt.
Sometimes dew on top of the quilt is a problem too as well as rain/spray with a minimalistic tarp.
A short list of partly flawed solutions:
- Just a tarp with the normal (breathable fabric) quilt and a ground cloth beneath it. Best solution when (heavy) rain is unlikely, when trips are short and when nights are warm. If two or more of these conditions are not given it is less than ideal.
- A tarp plus an UL bivy with a waterproof bottom and a breathable nylon top with a DWR finish. It is condensation resistant enough for warm and dry weather but acc. to https://40yearsofwalking.wordpress.com/2011/07/04/the-bivy-condensation-conundrum/ and the long discussion here https://backpackinglight.com/forums/topic/74239/ it has more condensation problems than event.
- Full eVent bivy: relatively heavy, bulky, pricy and still requires a tarp on top because I want to be able to get in and out of the sleeping bag without getting wet if it rains.
- Tents: relatively heavy, pricy, unbearable condensation problems from wet flys. Potential for condensation inside the quilt from perspiration like with the two options above.
- A minimalistic tarp plus a VBL inner bag and a fully waterproof non breathable over bag – this is basically the same solution that I am suggesting below but heavier and bulkier yet more versatile if you want to be able to use the quilt in a non-vbl setup.
Suggestion, “VBL Quilt” (a myog project): A quilt with a completely waterproof fabric (e.g. silnylon) on both sides. The seams would have to be sealed of course (or there are non, see below).
Advantages:
- No need to worry about wet down since the quilt (and the down in it) is sealed from all sides.
- It’s super light since you can do two of the following things: ditch the VBL inner bag, ditch the (heavy event) bivy, make the tarp a lot smaller – tents (option 4) are not an option for me because of their weight and condensation problems.
- Compared to the (VBL-bag + waterproof bivy) solution you safe 5 layers of fabric which amounts to at least (leaving out draw cords, seam sealing etc) 300 grams of weight (assuming that the weight per m² of a lightweight waterproof fabric is 30g/m² and one layer has 2 m² if you don’t want to feel too constraint).
- You can vent the “vbl quilt” solution if it is too hot which is not possible with the (VBL-bag + waterproof overbag) solution because that would compromise the VBL attributes of the latter. I have omni tape (similar to velcro tape) glued to the bottom of my sleeping pad as and omni tape on both sides (full length) of my quilt which allows me to fix the quilt under the slepping pad which eliminates drafts but also allows for ventilation if needed.
Disadvantages (and their solutions):
- It might be a bit sweaty if the quilt is too hot for the weather but I consider this the better alternative compared to wet down, especially if you don’t have the ability to dry the bag. . Also this should be less of a problem because I wear plenty of cloth when I sleep which should soak up most of the moisture.
- Another disadvantage is that this “VBL quilt” is less versatile, i.e. less appropriate for really warm, dry nights where condensation isn’t that big of a deal.
- Also I might have to seal a lot of seams or use tape to create the chambers that limit the movement of the down. Another option here could be to not stitch the fabric at all and have the down float freely (no chambers), I then would have to shake the down in place every time before going to sleep. This no-stich version should be best for +10° Celcius weather where potential cold spots aren’t devastating.
Discussion:
- I have not seen a discussion of this solution. I am happy about any thoughtful comments that point out things I have not considered…
- …as well as in field experience with how comfortable / bearable the moisture build up with a VBL style sleeping system is since I have no experience with VBL myself (other than sleeping in a plastic bag at home to get a feel for it which wasn’t too bad).
- Also, is anyone aware of a commercially available “vbl quilt”? I searched for fully waterproof quilts / sleeping bags but only found those with WPB uppers.
