I'm pretty sure that Vaude were doing this ten years ago, in fact I'm certain as I have one of their waterproof, welded seam, backpacking sacks which I bought in 1997 before walking the Pennine Way.
Mine has normal zippers (but with large storm flaps) but they also did a pack with a roll-top (dry-bag style) main and bottom pocket fastening which was submersion proof. The same technology was also available on smaller day-pack sized bags.
Yep - I remember the Vaude packs from years ago - or at least the small roll-top day-pack thingy with the straps attached to it. I took the straps off mine and now use the roll-top bag as a bomb-proof rucksack liner.
You're both right. VAUDE were the first to use ultrahigh frequency welding (UHFW) to make waterproof rucksacks nearly 10 years ago. However this new technology uses ultrasonic welding technology. There are two main advantages - 1 - you can weld in 3D rather than the 2D of UHFW - so you get a more functional sack that looks great and is easy to use. 2 - you can use normal rucksack fabrics, rather than the heavier plasticised ones needed on UHFW, so the pack is lighter 800 gms for Aracanda 30, as well as more abrasion resistant.
I've got a 30l craghopper one that has the internal sack as a dryback. The thing I find confusing/funny is, you've still got to have some other kind of bag to put damp things into eg if it rains then stops, what do you do with your damp jacket? Put it in a bag in your waterproof rucksack!
If you were to fall in whilst crossing a river or stream I don't suppose the waterproof rucksack would do much good once water had seeped in under the lid. I usually keep each individual item of clothing etc in it's own water tight bag and then inside a rucksack liner. Those large zip lock freezer bags you get in the supermarket are pretty handy for some items.
This was a nice pack as long as it lasted. The materials felt very plastic, but it was light and functional. However, after about one year the welded joins starting falling apart. This was when it was still fairly new and I never load it much. After something like three years all joins were coming apart, and the bottom ones were open so much I thought it would open completely if I filled it. One litre Nalgene bottles would fall out of the openings, that's how big they were. So sadly, I threw it in the rubbish last week.
I was choosing between this one and an Osprey. Now I'll be buying an Osprey. Will be interesting to see how it holds up.
