Originally Posted by sturgeon
I'm no expert, but I think the sil version would really block all rainsplash from the ground as well as sideways rain from hitting your underquilt. Like, totally and completely 100% block it.
That's good, but since it is waterproof that means it isn't breathable, so there's a possibility of condensation of the moisture from your body forming on it on a cold night, and soaking your underquilt. That's bad. Maybe there's enough air getting in there to stop that, but I don't know.
On the other hand, in extreme temperatures well below freezing, where there's obviously no risk of rain, the sil version could be used as a vapour barrier, by putting it between the hammock and the quilt. The moisture from your bod would form on the sil, and your hammock might get wet, but you'd be warm and your quilt would be bone dry.
As i say, I'm no expert. I bought the breathable version just to have an extra layer to block the wind that robs my Underquilt of its warmth. I figure the amount of rain spalsh under my tarp in even a big storm is not great, and the non-sil nylon should be able to handle it. I'm not into winter camping so I don't need a vapour barrier.
Here is another approach, though be sure to experiment in safe conditions to assure that it will work for you: the classic VB inner layer with an outer waterproof layer approach.
Instead of using the sil-UQP as the VB, use a space blanket over the UQ ( or wear VB clothing if you swing that way like I sometime do). In edition to picking up some extra warmth from the space blanket, it should function to keep user body moisture out of the UQ. If it doesn't, VB clothing almost certainly will. Both have worked for me in the HHSS and PeaPod many times with no problems. And just ask Wisenber about some of his incredible positive results using VBs to take quilts WAY past their normal ratings plus keep every thing bone dry.
Now, using this approach, the sil-UQP can provide bomb proof protection from both wind and moisture from the outside. With the VBs taking care of moisture from the inside. Not for every one, but can be very useful for some. And the added benefit of an extra 15 plus degrees.
Of course, most people will prefer the breathable approach.