Pack Cover Vs Pack Liner

You don't want to use your regular kitchen trash bags. They will stretch tear holes easily. What you want are trash compactor bags. You should be able to get them at a hardware store. They are very tough.

You could use both a liner and a pack cover. Pack covers have proven unreliable for keeping your pack completely dry (rain trickles down your back and soaks into the pack, you fall into a river, ect.), but I remember somebody doing a test and found out that the additional weight of a pack being water soaked was equal or heavier than the weight of a pack cover. I could be mistaken on that though.

I didn't even think of the pack being heavier with the soaking of the water. To be honest though all our trips have been a day's walk back to safety so if the weather turned nasty we'd just leave I think. If I was on a 4 or 5 day through hike it would be a different story.

I got a ULA Circuit, the material doesn't seem to be able to soak too much water and it's thin….still though it 'could' easli account for extra weight.

You said that pack covers have been proven unreliable as water trickles down your back and still soaks the pack. It's settled then….compactor trash bag it is then :)

Mik,
you can put the soaked pack into the reversed compactor bag if the latter is big enough.

I use The Packa as my pack cover AND rain gear. It prevents that issue of water running down your back and soaking your pack from the uncovered side.

It’s also a great rain jacket with huge pit zips, but it is a dedicated hiking jacket in that you don’t want to be wearing it to the store around home.

I have been using either a pack liner, or a few dry bag for my sleeping bag etc.. for a few years.
But when i hiked the CWT in Scotland in may a few years ago, if my gear stayed dry during the 8days of 24/24h rain/snow, my exos 58 was drenched and i was carrying a ton of rain water.
My wife was using an ULA catalyst + rain cover, her backpack stayed mostly dry.

Since then when i hike in Scotland or similar regions i use a Zpacks cuben fiber pack cover.

Later at home i did some testing , drenching a backpack ( talon 44 ) hanging it uppside down for 5 mins and weighting it.

the talon 44 added weight from water was about 450g/1 lb !!!

for the 2012 TGO i was using a zpack cuben fiber pack cover over my exos 58 and it stayed dry despite the first 10 days of scottish weather we got.

The following is a post I wrote on 6-11-11. For the full thread, click on this:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=49136

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. 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 8 oz.

Good experiment

How much extra would the pack cover weigh if it was wet?

I discovered an unexpected advantage to a pack liner this summer on the JMT. I fell during a stream crossing and was literally laying in the water. It was a sunny morning so did not not have a pack cover on, but because I had a pack liner all my gear remained dry.

Jerry, do you mean "How much do the beaded up water droplets weigh before they fall off the pack cover?" I'm not trying to be snarky, but I'm thinking that a pack cover won't increase in weight at all. They're waterproof, right?

I guess you're saying the answer is the cover wouldn't gain hardly any weight

It must be made of plastic that absorbs no water. And there'de only be a few drops that hadn't fallen off yet.

What about the water that drips off between the pack and your back? Of course that would be the same whether you had a pack cover or not.

Where is that 11 ounces of water on your pack when it gets wet? If it was on your backpack straps, the cover wouldn't help.

Not trying to prove you wrong or anything, just drilling down a bit : )

No, you're absolutely correct, Jerry. My entire pack was soaked, every part of it. It was pointed out by Dale in the above thread link that a pack cover won't keep the foam back panel, the waist belt, or the shoulder straps dry. On the other hand, I would expect these areas would tend to dry out rather quickly once the rain stopped, since they are in close contact with your warm body.

I also think that the results from my patio test and Eric's relate to the different pack fabrics. A Talon 44 would certainly absorb more moisture than an Absaroka, and also probably dry out more slowly.

Wow, there is a lot to consider.

I went to the internal trash compactor bag many years ago and this thread is prompting me to recall why. These thoughts/memories come to mind.

I currently make my backpack bags out of uncoated nylon and put my dry stuff in a trash compactor bag inside the pack. The rain simply runs down and over and out and when it stops raining the backpack bag dries out quickly. Coated pack bags eventually get leaks somewhere and those leaks work very well at letting water in but not so well at letting water out. I've had puddles of water gather in the bottom of coated pack bags.

With a pack cover I've also found I can wet things under it with moisture from my own body. I sweat a lot and the humid air from this sweating manages to get under the pack cover and condense on the inside. It isn't a great deal of volume but it quickly shattered my hope that a pack cover would keep my pack bone dry.

Yes, a wet waterproof pack cover will carry some weight. Think how heavy a wet rainfly is when you pack it.

A pack cover itself will eventually leak so it is one more thing to patch and seal.

A wet pack is not that big of a deal in camp, especially if it is uncoated fabric. Things dry quickly to the point of just feeling damp. The pack can be placed under the vestibule, under the sleeping pad at the head or foot or even under the ground cloth/floor if it is wet and, say muddy. Totally soaking wet clothes from rain or sweat(my problem) is more of a concern for me.

My wife uses a poncho (aka pack cover) and an internal trash bag and doesn't sweat much. She is able to maintain a relatively dry micro climate under the poncho, even when it is raining heavily.