Reading Alan Dixon's article on hiking in prolonged rain, I was struck by a sentence after his discussion of the importance of DWR in WPB rainwear. Here's what he said about rainwear that has wetted out:
"At this point, your waterproof/breathable fabric breathes little better than a totally non-breathable material like a plastic bag."
That got me thinking. Until a rain jacket wets out, the DWR causes water to simply roll off the shell and the waterproof layer underneath doesn't need to do any work. Presumably, the DWR on a windshirt is (or could be, theoretically) no worse than the DWR on a hardshell or rain jacket. Up until the point of DWR failure, therefore, a rain jacket is essentially a less breathable windshirt.
After the point of DWR failure, per Dixon, a WPB jacket is essentially a trash bag—some would say a less waterproof trash bag (I'm thinking of Skurka's photo where he had to layer a trash bag over his rain jacket.
So why do we bother with WPB jackets at all? Pre-DWR-failure, it's worse than a windshirt. Post-DWR-failure, it's no better than plastic or silnylon. Why not bring a windshirt, use that in light rain, and then swap to a non-breathable shell (plastic or perhaps cuben or silnylon) when that wets out? The combined weight and price could easily be less than a WPB jacket
The main wrench that I can in this system is that a WPB jacket won't wet out all at once, but parts will remain breathable while other parts are trash-baggy. Perhaps a plastic cowl that covers just the neck and shoulders would provide my system with similar flexibility.
Thoughts?
