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Wet Pack Questions
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May 13, 2014 at 7:56 pm #1316800
I've seen recommended use of a compactor bag as a pack liner frequently here at BPL. But I'm struggling with why we'd let the water get that far in the first place. Why let the pack get soaked–how is that UL? Wouldn't it be better to wear a poncho over yourself and the pack, or at least use a pack cover? And while we're on the topic, why does a pack need to breathe? Why not just waterproof the heck out of the pack fabric? Likely obvious answers to all this but as an UL noob (ha, not even that, at 12 lbs base) I don't understand the liner strategy.
May 13, 2014 at 8:05 pm #2102144Some pack covers weigh more than the water absorbed by the pack. They get caught on stuff and make getting to side pockets difficult. A waterproof pack is waterproof until the first hole. Some people hate ponchos or hike in areas where they are not a good choice. A liner gives me a dry place to store wet gear inside my shelter. The liner strategy works for me. My Ohm does not seem to absorb much water and dries quickly.
May 13, 2014 at 8:27 pm #2102149I don't understand the need for pack covers or pack liners or ponchos.
Each time I buy a new pack, I spray a little waterproofing stuff on the inside of the pack. Then it seems to be almost 100% waterproof from then on, and I never have to fool with any of this.
–B.G.–
May 13, 2014 at 8:30 pm #2102151What kind of waterproofing spray do you use?
May 13, 2014 at 9:00 pm #2102155I have used trash compactor bags for many years and they have not failed me. I put my down sleeping bag and any clothes I will not use that day in the bag and roll it up like a long elephant trunk. However, this past year I was caught in an sudden winter storm with lots of rain and a couple of feet of snow. I made it out in two days but five PCT thru-hikers had to be rescued. This was in the north Cascades of Washington. My pack wetted out and all the contents in the bag that were not in the trash compactor got wet as well. I am guessing it added at least a pound to the overall weight. It was it miserable trying to dry out everything when the temps were in the mid 30's and no way to build a fire. I now have a waterproof pack cover for long expeditions in the shoulder seasons.
Keep dry and good hiking.
May 13, 2014 at 9:06 pm #2102157I remember a thread where someone weighed their wet pack and determined that a pack cover weighs less than a wet out pack.
You should probably still have your down bag in something waterproof. I mean, what happens if you fall into a creek? I know that's unlikely but in certain situations getting your down bag soaked could put you in a serious survival situation.
May 13, 2014 at 9:17 pm #2102159Don't forget that even if the wet pack weighs slightly more, you would always be carrying the weight of a pack cover….the wet pack when dry would weigh quite a bit less.
May 13, 2014 at 9:36 pm #2102162> Each time I buy a new pack, I spray a little waterproofing stuff on the inside of the pack.
I'd like to try this. Why spray the inside rather than the outside? And what product would you recommend? Thanks.
May 13, 2014 at 9:51 pm #2102172"What kind of waterproofing spray do you use?"
Didn't we just go through this the other day?
I spray on some kind of Scotchguard spray in an ancient aerosol can and try not to inhale the fluorocarbons.
If you spray it on the inside surface, eventually it might peel up and look bad, but nobody will see it.
–B.G.–
May 14, 2014 at 12:56 pm #2102395"I spray on some kind of Scotchguard spray in an ancient aerosol can and try not to inhale the fluorocarbons."
That is a water repelent coating not a waterproofing agent. In sustaid heay raid the water will get through and it will not keep your sleeping bag dry if you fall in a creek.
Many packs have a polyurethane coating on the inside surface of the fabric that makes the fabric waterproof. However the seams (wich are typically not taped or sealed) and zippers will still let water through.
"If you spray it on the inside surface, eventually it might peel up and look bad, but nobody will see it."
the spary will not deposite enough material for pealing to occur. However polyurethane will eventually degrade, peal, delaminate, or turn sticky.
May 14, 2014 at 12:58 pm #2102396Gah, where are you folks hiking? It sounds like paradise with no rain. A little waterproofing spray on the inside of the pack won't do much around here when it's raining hard for three or four days straight. I have a cuben pack liner, and a pack cover, and on trips when I'm expecting real rain, I put my down bag and down jacket in a roll-top drybag inside the pack liner. All of this weighs maybe 6 or 7 ounces, tops — and it would be less if I wanted to spend more money on cuben.
May 14, 2014 at 1:56 pm #2102412Ken, the waterproofing advice from southern Cal is often bad advice for people in our part of the country.
May 15, 2014 at 1:01 am #2102569Delmar,
Back to your original question. It's pretty simple in my mind:1) When you use a waterproof lining, you actually separate the abrasion layer (your pack) from the waterproof layer (your lining). This is a big deal. Your pack can take all the beating from the outside world while your waterproof liner stay protected (and hence, stays waterproof). I can't overstate how important this is in real world use.
2) A waterproof plastic liner is A LOT easier to field repair than a compromised "waterproof" pack (or a pack cover/poncho). All you need is some tape to repair the plastic liner bag. With the waterproof pack or a silnylon pack cover… well… Good luck with that.
3) Last but not least, a pack cover doesn't really waterproof your pack's contents in real life. What happens when you slip during that river crossing and take a dip? That pack cover isn't going to do squat to keep your precious down feathers dry in this situation. Just remember that rain is not the only thing that can get your pack's contents wet.
May 15, 2014 at 2:21 am #2102570Pack covers are a single use item that don't even work that well and are expensive.
If you really want something on the outside of your pack, that's fine, but why not just use another trash bag?
Finally, pack covers are one of those things that were invented to be an add-on sale in retail space. Just like a tent footprint and just like a sleeping bag liner. If you're outside, things are just going to get wet and dirty and smelly. Trying to eliminate that fact with extra purchases are irrational.
May 15, 2014 at 5:00 am #2102573I have always used a pack cover to great effect. Liners are fine but pack weight can increase significantly if wet. No theory here required. Use what you prefer.
May 15, 2014 at 7:24 am #2102593Depends on the pack material. As far as I can tell, neither my Osprey Exos packs' material or padding absorb or hold any meaningful amount of water, and are dry within minutes of being soaked. Contrast that to something like my Mystery Ranch pack with heavy padding for the shoulders, hips, and back, plus much thicker packbag material that visibly wets out, and it's not hard to see that this is a very different thing from one pack to the other.
I use OR's ultralight waterproof pack liners, as they are a good fit for my particular packs. Not very durable, but protected by the pack, easily patched, and proven. Brief chest deep water and several intentional submersions when using my 46L Exos as a daypack in the Zion Narrows and Orderville Canyon sold me on both the liner, and the pack's ability to shed moisture.May 15, 2014 at 7:28 am #2102595I gave up on pack covers long ago.
I sweat heavily and the sweat enters the pack from the side against my back.
The humidity from my sweat collects on the inside of the pack cover so the pack cover and outside of my pack get damp/wet even if the rain doesn't come through the pack cover.
Trash compactor bag for me.
I use uncoated nylon for my pack bags. Water drains through and things dry quickly. I can also throw the bag into the washer after each trip.
May 15, 2014 at 8:29 am #2102602"Finally, pack covers are one of those things that were invented to be an add-on sale in retail space. Just like a tent footprint and just like a sleeping bag liner. If you're outside, things are just going to get wet and dirty and smelly. Trying to eliminate that fact with extra purchases are irrational."
That is exactly right. A wonderful way to send an economic "shout out" to a big tent/pack/sleeping bag manufacturer is to shell out $30-$50 on a very cheap piece of material designed to take the beating on behalf of your equipment. It's not a bad idea to use a cover/liner/footprint, but I prefer buying/making something just as effective but 90% cheaper.
Using a trash bag inside the pack has always been a great idea. I use a water bladder and I'd be a fool not to store all my stuff I don't want to get wet in something waterproof and keep it separate from that water bladder. Once my clothes come out and happen to get wet, they don't go back in the liner until they are dry.
If my tent is wet from the rain, I usually stuff it on the outside of my pack to dry it out & wrap some of the cordage around the pack. A tent body/fly can always make a decent pack cover as well, if you have good knot skills. A good multi-use piece of gear.I will usually carry a 2nd trash bag to throw over my pack, esp. if I believe it might be potentially bad. It's a snap to drop over the pack, tear two holes for my shoulder straps and throw it back on my back. And it's entirely reusable.
Now that I think about it, if I were fording through a deep stream, I suspect I could simply reverse the trash bag, and put my pack down inside it, slip my shoulder straps through the same holes, put it back on, and likely reduce the chances of water getting into my pack. (Since I understand it is NOT GOOD to wear the waist belt while fording a stream anyway, the belt probably won't mind being in the bottom of the trash bag during this event.)May 15, 2014 at 11:56 am #2102647AnonymousInactiveHi Delmar,
I'm trying to develop a sort of half, minimal poncho that is more for the pack than full rain protection. I thought about it after experimenting with a quasi Paramo type set up (wind jacket [Houdini] with Cioch pump liner). Partly because of the backpack straps and pack weight, partly because of the non sealed Houdini seams, and maybe because the Houdini isn't quite water resistant enough to begin with, i experienced getting wet primarily through the shoulder areas.
I use a pack liner, but i also don't like how the packs absorb water and get a bit soggy and heavier.
So i thought i would kill two black desert ravens with one stone. A half, minimal poncho. Basically it's just a rectangular piece of silnylon, with a slit cut into it about 3/4 of the way towards the front of the fabric–slit is reinforced on sides with sewn fabrics, then a couple of loops sewn on on the back part which goes over the packs and have some shock cord with cord locks put through the loops to keep it taught on the pack.
Provides extra shoulder protection (which is where it's usually most needed with any worn WPB that goes under pack straps, but especially Paramo type), and provides full pack protection, all at a pretty low weight and cost. Haven't finished it completely. Need to attach the loops and cords. Tried it out without those and needless to say, wind and just body movement tended to shift it around too much to be practical.
Note, i will still use a pack liner. If one isn't using a paramo type system, then other gear makes more sense, either full poncho, or the like. I like my system because, if it's warm out and warm rain, i can still protect my pack fully while having a lot of breathability otherwise and let most of self get wet. When it's finished, i will probably put up some pics on MYOG section. I don't remember exactly how much it weighs so far without the loops, shock cord, and cord locks, i think it was around 3-4 oz, but i will check and update accordingly. It will get a bit heavier with the other stuff added on.
May 15, 2014 at 12:21 pm #2102654The following is a post I wrote on 6-11-11. For the full thread, click on this:
Pack liners vs pack covers
I did a little test on the patio a couple of weeks ago. I wanted to see how much added weight a fully-soaked pack would have, and to also test the waterproofness of cuben roll-top bags. I used a 42 L. Absoroka pack, with one of Lawson's cuben pack liners stuffed with fleece jackets. Rain drizzled nearly all night, fully drenching the pack. The next morning, I emptied the pack and hung it up for 30 minutes to let the excess water drip off. It turned out that the roll top liner had fully protected the contents, and that the drenched pack was 11.0 oz. heavier than when it was completely dry. So…this might support the case for using both a liner AND a pack cover when you know that you will be hiking in full-on rainy conditions. A 3 oz. pack cover could lighten your pack weight by a net of maybe 8 oz.
May 15, 2014 at 1:15 pm #2102667A pack cover does nothing at preventing the saturation of the padding in the straps, belt, and back. Seems to me that these are the areas that would account for the real water gain in a wetted out pack, so the comparisons made between cover weight vs wetted pack, seem artificial IMO.
May 15, 2014 at 1:55 pm #2102678Moreover, I've never seen two packs alike.
I would imagine the simple act of "using" a pack would likely increase it's capillary abilities over time no matter what one does, simply from the stretching of seams and abrasion due to normal wear and tear. If the pack isn't advertised as "waterproof", I'd wager that two identical packs off the wall at REI would respond differently to a deluge, simply due to when they came out of manufacturing.
May 15, 2014 at 1:56 pm #2102679I agree with Glenn. If your pack weighs 11oz more when wet and a pack cover weighs 3 oz, your weight savings will not be 8 oz. Your pack will still absorb water.
Regarding waterproof pack fabrics: I find their greatest benefit not to be that they keep the inner contents 100% dry, but that packs made of waterproof fabrics gain little weight when wet. My HMG pack, for example, has very little exposed foam and does not seem to weigh much more when wet (although I have never weighed it when wet, so I cannot verify this).
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