Bivy Fit Question

[8Crow]

Question for all you experienced bivy users out there...what sort of "fit" are you looking for? Let me explain. I have:

• Marmot Couloir Down 0 deg long bag
• Exped Downmat 9 Long/Wide
• Mountain Laurel Designs Superlight Bivy - Large

According to MLD's page on the superlight, the large is made for folks up to 6'6", pads up to 78" long and more than 2.5" thick, and for large winter bags--all of which I have.

I am 6'5", 210 lb--built like a toothpick except for a little gut. And when I crawl in this setup I can tell it is compressing my bag to some degree because it is restricting my movement. So that is the basis for my question--when you crawl in should the bivy sack drape loosely over your bag, or should it be a little tight? This is clearly my first bivy and I just always assumed they should be a little loose.

I know that generally speaking, loft = warmth, so I don't want to lessen the ability of my bag. But it seems like this sack is made precisely for my setup so I'm confused.

 

[Lawnboi]

If its compressing the loft, it dosnt fit. Your losing some warmth.

Of the bivies I have used the current bivy I have used is a ID bugaboo II bivy and it is very big compared to the others I have tried.

 

[Trout bum]

That pad is pretty thick. I ran a similar setup and kept the pad outside the bivy to avoid that overstuffed burrito feeling.

 

[Bughalli]

Yeah, you don't want it so tight that its pushes down the loft of your bag. You need that loft for warmth. I would go a bigger bivy.

In terms of the pad, I prefer to keep it inside. It's much much warmer. Plus its too easy to slide off the pad in the middle of the night when it's outside the bivy. No fun at all if dealing with frozen ground. Creates cold spots. You also don't want water to collect between you and the pad. That late night rain will make you cold.

I like to have a little extra room for keeping other items warm (morning clothes, damp items if you need to dry them out or to keep water from freezing). Or if I get hot in the middle of the night and want to take a layer off.

 

[8Crow]

Thanks all, that's really what I was thinking. I contacted Ron at MLD and he agreed I need a bigger sack, told me to send the large back with a note requesting an exchange for an XL (not a published size...the beauty of a cottage shop). For those of you trying to cut pack weight I would give these a look...6-7 oz depending on which size you go with, it packs down into a tiny little stuff sack, and they're actually cheaper than some of the others I've looked at.

 

[mmw194287]

On a related note, does anyone here run a bivy with the BA classic or classic SL series? I like the idea of the semi rectangular footbox, but I have my doubts about its compatibility with most bivy sacks. Any thoughts or experience out there with these bags?

 

[Hunt'nFish]

On a related note, does anyone here run a bivy with the BA classic or classic SL series? I like the idea of the semi rectangular footbox, but I have my doubts about its compatibility with most bivy sacks. Any thoughts or experience out there with these bags?

I have an Oware Std Zip Long and run a BA Q-Core Insulated 25x84x4 pad w/ a couple warm weather holofill rectangle bags. I'm a big guy 6' 250lbs and it seems fine.
Don't like the top zip though, If I were buying I'd look to their XL Side Zip. (See pic below)
It's a little heavier bivy, but I think the larger demensions accomodate the larger high loft down bags better. Whats a couple ounces anyway?!?
Hunt'nFish

Oware Side Zip Large Long Bivy

 

[mmw194287]

Thanks Hunt'nFish, I'll have to check those out.