I am looking in to ways of setting up a tarp as a shelter and am curious if others here have experience with using them specifically in the rain.

The 2 methods that I have in mind are a lean-to with awning and an A frame style.

I have used tarps before as a make-shift shelter, but that has always been in dry weather. Both times were sort of like a hotdog bun style bivy - I put part of the tarp down as a ground cloth then wrapped the longer portion up and over. I've done that both with and without a ridgeline, not a very high ridgeline, just enough to give maybe 4-6" clearance of me laying down.

For getting rained on it would seem the A frame would be the wisest method as it gives 2 complete walls (if the sides go all the way to the ground). However, that leaves both ends open. In air that isn't moving too much, even if the rain is fairly heavy, that would be OK I would think. However, if the wind picks up there is the proverbial "wind tunnel" going through. Has anyone experienced this? What thoughts do you have and are there methods you've found to stay totally dry in such a simple shelter?

My thoughts are to use a tarp as a quick, simple shelter, but I am a bit hesitant unless there is no risk of rain. The last thing I want to do is be in a wind tunnel at night and soak my gear.

I do have several of the SOL bivy's. I experimented with them a few years ago and I have a "breathable" one I got after the first "experiment". The first one I used was not breathable and made for quite the clammy night - so much so that I got out of it in the middle of the night. I had it layered over a synthetic sleeping bag. I figured the "breathable" one would be a lot better. Not so - I ended up with the same scenario.

As to the tarp idea - a bivy inside it like one of the SOL's would be ideal - the tarp as the fly and any water that makes its way inside doesn't get the sleeping bag wet. However, the condensation issue with the layer over top the sleeping bag makes that a no-go in my book. Even though the "breathable" bivy vents on both ends (it uses velcro closures so you can open it up) it doesn't vent enough, I don't think .Maybe if there were a way to turn it in to a more open air "fly" over top the sleeping bag that might help? Not sure how to rig it yet.