This week's Kit Tip is one for all of you who want a waterproof rucksac – we're often asked which packs out there are actually waterproof, so if you're wondering here's the low down.
First, most rucksacks aren't waterproof. The fabrics they're made from are generally coated and are waterproof, but normal pack construction means that in any sort of serious rain, water will leach in through the unsealed seams soaking the contents comprehensively.
Sealing pack seams is difficult and exensive – taping is awkward to apply, particularly over bound seams. And the other obvious solution – 'welding' or gluing seams is looked on with suspicion by pack brands who feel it doesn't create a strong enough seam bond.
There are exceptions though. VauDe has several packs using what they call Ultra Seam Tech technology, which basically means the main seams are bonded and taped. Even though the seams along the back panel are normal, it's enough to make the packs like the Tec Rock 32 pictured highly water resistant in the real world.
Berghaus has taken a slightly different approach to the problem. Packs like the Sentinel 35 feature their InterActive Dry Liner technology, basically an integrated liner come drybag that's 100 per-cent waterproof. Of course the rest of the pack is conventionally stitched and not sealed, but the contents should stay dry.
Talking of dry-bags, a couple of brands produce minimalist sacs, which are essentially dry-bags with some basic back padding and a set of shoulder straps. They're light and simple and with their sealed seams and roll-over tops, completely waterproof. Exped's versions mean you can't also accommodate a hydration system, but those cunning chaps at Alpkit have added a hydration bladder pocket to their Gourdon packs so you can have your cake and drink it too...
And if you can't be doing with a completely waterproof pack, you have a choice – pack liner, a rubble sack with folded-over top makes a good budget option – or a pack cover, which has the advantage of keeping the main body, though not the harness section of your pack, dry.
So there you go. You can keep your sarnies dry...