Been raining heavily all day today at home – got me thinking about my dry bags, would they keep my down sleeping bag and jacket dry if I was backpacking in really dreadful weather ? – Yes, I am that bored today !
I thought the easiest way would be to put some water in the two brands of dry bag I have and see if water leaks out of them. I have 2 Pod ultra light dry sacks and 2 Alpkit airlok dry bags. On the Pod website it states: Ultralite, waterproof Nylon stuffsac with roll top closure. Ideal for packing and organising outdoor kit in potentially wet environments when the grams count.
Alpkit site : Airlok waterproof bags are ideal for keeping your stuff dry when crossing rivers, sneaking around in Amazonia or kayaking off Newfoundland.
All four sacks leak around the taped seams, some less than others. I noted that the material did not leak just the taped seams I not sure whether this is a fair test and whether you can relate this to the real world of backpacking in heavy rain.
I guess you would not usually have that sort of water pressure on the seams in normal usage.
My next test was to put a dry cloth into the bag, place the bag into the sink, run water on the bag and allow to stand for 2 and 5 minutes in the water. In fairness to Pod, it does state on the label waterproof where the bag is not submerged. After the last test, I fully expected the cloths to be wet when I took them out.
However, at two minutes, all the cloths were dry in both brands of dry bag. After 5 minutes there was some small damp patches on all the cloths. A fairly stiff test to past as they are not dry bags in the sense of sailing bags.
So after this I placed an item of clothing in each brand of dry sack, put them into my OMM Jirishanca and hosed the backpack down from all angles for 5 minutes with a garden hose. Results no moisture on any of the clothing contained in the dry bags.
Mark's Rain Machine
As I tend to be a belt and braces sort of chap, and I did note some seepage when the dry bags were submerged, I think I will take the added precaution of placing down items in a plastic bag and then place them in the dry bag next time I go backpacking , but for other less important items I would not be that worried.
Has anyone found problems in the field or have any views on this ? – I would be interested to hear about them.
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Mark's walking blog 
Mark,
I don’t trust those bags. I always put a down sleeping bag into a separate drybag that is then put into my main drybag. I always visually inspect my Exped dry bags after each backpacking trip and have had to plug a few small holes with seam seal. It might be overkill but I don’t want to take the risk.
Whilst in my test with drenching my backpack with water, there was no evidence of moisture – so they are dry bags from that point of view. The fact that I was able to view some moisture coming through the seams – (OK in perhaps an unrealistic test) means that I will in future double wrap down kit. Imagine after a long day in very wet weather and looking forward to getting into your nice warm down sleeping bag and pulling it out wet. For saving a few extra grams I will not take the risk. With other stuff, I am not so worried.
Mark
Interesting, I never use dry bags at all – I rely on my pack liner (which is a very good Cascade Designs one except in sumer when I might use an Ultrasil one).
I did a post a while ago about Ultrasil pack liners and referenced an article by a guy who tested them by filling with water. Not surprisingly he found they leaked, but I don’t really know how that translates – if at all – into a useful indicator for the backpacker. They were designed to hold gear when enclosed in a backpack and the whole thing subject to falling water drops, which is very different from a mass of water under considerable pressure inside them.
Thanks for your thoughts Geoff, as I said in my post , I think that filling a bag up with water, is probably not a good way to test. So I ended up conducting my “rain machine test” with the garden hose as this is more realistic -( sort of) to the conditions of heavy rain. It did however get me thinking about the potential for leakage and therefore I am going to double wrap my down kit to be on the safe side. Do you use the standard stuff sack with your sleeping bag – I think you use Mountain Equipment and then place this into the pack liner ?
I just the standard supplied stuffsack and stuff it in with everything else. The Cascade Designs liner is relatively heavy but it’s very tough and rubbery.
I use a pack cover (as I am not a fan of wet rucksacks as they tend to hold the water, consequently increasing weight) and Sea to Summit drybags. The S2S bags have been ok so far but some poor reviews of the waterproof properties of silnylon can be found on Jim Woods Base Camp blog. It’s as detailed as you could ever ask for. That said, I’ve never had a drybag fail.
hello
Last year i bought an Aquaknot 1200 waterproof backpack (seattlesportsco) ( in July). It was a very good drysack for 6 months but now it has a problem near the logo. In the lower end of logo water comes in. I use the drysack in different conditions no problems till now. I belive the problem depends to the exessive deep track along the border of logo. The lowest end of logo creates the problem.
I wrote to http://www.seattlesportsco.com for a possible replacement but the response was negative.
Luciano