bivy or water resist/proof shell on bag?

Decide on the temps and weather you are gearing up for. A bivy extends the range of a bag (especially if there is ANY wind entering the tarp) and allows for a smaller tarp.

I like to opt for the lightest bag (higher temps rating) to cover most of my hiking and when it gets colder/nastier add the bivy and then more clothes.

Bivy Plus: In temps above about 55-60 you only need the bivy and your reg trail clothes.

Another GENERAL Example:

A 30 degree bag alone: Good for 30-55 degrees /light wind and low to med blown rain in a med to lg tarp with some clothing augmentation.

A 35/40 Degree bag and bivy, good for 25-70 degrees, med to heavy wind and heavy blown rain in a sm tarp and some clothing augmentation.

There are a lot of other variables that can factor in deciding if you need a bivy, more than one/two nights, shelter type/size, down or synthetic bag, season /humidity/daytime bag drying conditions/ etc etc etc

Basically, a bivy is just another tool in the SUL arsenal that lets you pick the combinations for a particular trip.

water-resistant/proof shells on sleeping bags aren’t seam-sealed, afaik.

you can shake underside frost build-up from a bivy. you can’t really do that in a sleeping bag.

HI Ron,

Thanks for the insight. I guess a bivy gives me a lot more options. I should also say I’m considering one of your bivy’s and I love the look of your grace tarps. My Oware tarp is 10×10 flat and it’s great but, if I need someting smaller I’m intrigued by the grace.