Check out the Cuben Fiber Dry Bag I built. It is 14" tall and 9" wide and will hold 5Liters.. I built it using the .75oz cuben fiber which is the same stuff I am building my tarps out of. It weighs 18.8 grams (.66 ounces). It is 100% water tight.. I plan to sell these in 5 or 6 sizes down the road. Price: Half Granite Gear's ($20.00??? For Size Shown)

Edited by Mountainfitter on 04/24/2010 22:21:01 MDT.

Glad you are being reasonable in your pricing...looking forward to their production

Lawson,
A smaller buckle, a la Granite Gear, would be nice, but I think a one-way purge valve will be essential. (Also on one of the GG products.)

That way you can fill and seal the bag, stuff if in your pack, and as you load gear on top the air flows out, allowing the bag to compress, and simultaneously flow into all the nooks and crannies in the bottom of your pack.

The best of all possible worlds, IMHO.

Otherwise you're packing a balloon.

+1 on the valve. Worst aspect of the drybag is getting the air out.

Only the much heavier Granite Gear air bags have a port or eVent panel to expel air - the ones they make from Cuben do not.

I've found with my personal Cuben dry bags I can load them and then either compress a soft goods clothing item in the bottom or easily suck out most of the extra air in one inhale by mouth while holding the top semi closed and then rolling quickly. So far so good...

I think some things work well in the dry bag style and others better in a reg cord lock style top.

I use the Granite Gear eVent-bottom bags (AirVent Reduction DryBloc Dry Sacks)+-++ and like them a lot. All my sleep items go in, it gets closed up, I squash it and put it in the bottom of my pack, and then start loading other stuff in. But they will "loft" and suck air in, unless you keep leaning on them.

So a light Cuben bag, with a one-way purge valve, will defeat the "re-inflation", making the packing process easier.

Just my style.

Good Point on the Purge Valve but when I first built it, if you pushed hard enough air would slowly leak out around the top were the buckles are. To test its waterproofness I did two things. First I filled it up with water and hung it for 24 hours and had no leaks then I threw it fully loaded and sunk it to the bottom of my pool for 24 hours and it also had no leaks but then again air molecules are smaller then water molecules. I wanted to try and use it as a pillow and have it be 100% air tight so I silicone sealed it but I think I like the other way better especially since it helped for closing, was water tight and isn't comfortable as a pillow. So maybe the first way was better after all????

Edited by Mountainfitter on 04/25/2010 23:37:38 MDT.

"if you pushed hard enough air would slowly leak out around the top were the buckles are"

True. But it takes a Really Long Time to get all the air out.

Plus, I don't have enough room in my pack for an extra liter or three of air.

But that's just me.

LK
If I sent you some re-cycled eVent could you make these like the Granite Gear eVent Sil Dry Sacks? http://www.granitegearstore.com/AirVent-Reduction-DryBlocs-P110.aspx

If you can, what would you charge for say a 10 liter one?

Exactly!

PM incoming.

Richard,
I use the GG AirVents and like them a lot. The only issue is that they will "re-inflate" rather quickly if they are not constrained. I just keep leaning on them as I pack additional gear in on top.

That's why I suggested the one-way purge valve. Once you get the air out, and squash the bag into your pack, it will stay that way until you lean on it again.

The .75 cuben won't save much weight over the silnylon used by GG. But Cuben and a purge valve (minus the GG closure strips) Should be a bit lighter than the AirVent, you getting the best of all possible worlds.

Edited by greg23 on 04/26/2010 12:17:41 MDT.

Greg,
I have two Sea to Summit eVac Dry Sacks with eVent on the bottom (13 liter, 2.4 oz) and one Sea to Summit Pocket Solar Shower, which is a dry bag with a valve (5.2 oz). I do not have a re-inflation problem with the eVent sacks. I close the top by hand and roll down tight, which forces out the air, until I get it as compressed as I can, and then connect the side release buckle.
There's nothing wrong with either, and I've been told on over on White Blaze that the GG eVent sil sacks work perfectly also. I'm just being a gram weeny for an AT thru I plan.