Two Types of Bivy Sacks
There is no other outdoor shelter that is as simple as the bivvy sack. If you can handle being in a confined space it’s a good substitute for a camping tent. There’s a reason why some people prefer to use a bivvy sack than to share a tent. They probably don’t want to share a bulky, heavy 2-person tent with a smelly, grubby mate. With a bivy sack, you can arrive at camp, crawl in, and go to sleep.
Waterproof Bivvy
If no water can come into the bivvy sack, it can be considered as stormproof. You can use a stormproof bivvy sack alone even in bad weather. The fabrics, seams and opening determines whether a bivvy sack is stormproof or not.
The fabric used in stormproof bivvies are generally waterproof yet breathable fabrics such as Gore-Tex. Fabrics like these not only prevent water from seeping through but allows vapor to escape as well to prevent unwanted condensation.
The floor of these waterproof bivies are made of waterproof fabrics as well but not necessarily breathable. The typical fabric used for the floor is silicone-coated nylon. The floor prevents water from seeping through the fabric from the ground. The floor also has to be resistant to abrasions and punctures on rough ground.
To be sure that water cannot leak in, a stormproof bivvy needs to have sealed seams and waterproof closures as well.
Water-Resistant Bivouac Sack
If a bivvy sack does not have a waterproof fabric, sealed seams or stormproof closure it is only considered as water-resistant. You don’t need waterproof bivvies all the time.
Water-resistant bivvies are lighter than stormproof versions because all the features of stormproof bivvies including the waterproof fabric, seam sealing and waterproof closure add quite a bit of weight.
One less obvious advantage is that water-resistant bivvies are less prone to condensation. Vapors are expelled quickly before condensation occurs.
This type of bivvy is not suitable as a standalone shelter in bad weather but works great if there is additional shelter like when used with a tarp above or inside a cave. This may mean you have to carry some extra weight but only a small amount of tarp is required and you may not have to worry about condensation so much.
Despite advancements in breathable fabric technology, there’s still not one that’s good enough to completely eliminate condensation altogether. When there is a huge difference in temperature between the outside of the bivvy and the inside, where the outside temperature is lower, condensation is likely to occur . It often on occurs on the head end and the foot end of the bivvy sack. As long as you have good ventilation inside the sack, you won’t need to worry about condensation.
Technorati Tags: No Tags
Related Tags: No Tags
Possible Related Posts
No related posts
