Ultralight Bivy Sack Choice

[Christopher May]

Would like to get some input regarding choosing an ultralight bivy sack for use under a tarp or inside a single walled/vented tent. I use a Sierra Designs wicked fast 45degree down bag and plan to wear my Cocoon jacket/pants (when they arrive) while sleeping. The bivy sack will be for increased warmth, dew and splash protection.
The four lightest options I have found are:
1. Bozeman Mountain Works Vapr Bivy (Pertex Auantum) at 6.1 oz $190.
2. Montbell Ultrlight Gore-Tex Bivy Bag at 7.2oz, $160.
3. Mountain Laurel Designs Superlight Bivy (1.25 Silnylon Pro bottom and .8 Nylon Ripstop DWR top with bug net face) 6.25oz $105.
4. Mountain Laurel Designs Soul Bivy (1.25 Silnylon Pro bottom and .8 Nylon Ripstop DWR top with shoulder to shoulder zipper and double zip bug screen) 6.5oz $165 Optional 1oz folding wire for lifting bug screen off face.
I’m leaning toward #4 due to the bug screen but wondering if anyone has experience with this bivy or knowledge about the differences between this and the other options.

[Anonymous]

Chris,

You might want to add these to your list:

Equinox Ultralite $59.95 6.5oz

REI Minimalist $89 17oz

Montbell Breeze Dry-Tec $110 6.3oz.

[kevin davidson]

You might want to ask staffer Doug Johnson (who I believe has one of MLD’s epic bivys) or Paul Johnson
who often writes missives on the G Spot ( who has a customized Soul Bivy) about using MLD’s wonderful products.

I just received a Soul Bivy (Mon.), myself, and am impressed by it’s quality—but I haven’t used it yet–ask me after the middle of next week. I’m probably not going to use the wire and opt for a shock cord attached from hood to my tarp pole instead. It’s lighter and I think gives more breathing space.

The only other UL bivy that I think touches upon MLD’s level of design and quality is the BMW vapor bivy—but different design philosophy, opting for good DWR in Pertex instead of Epic in the MLD bivy.
Personally, I like the more water resistant qualities of Epic over DWR fabrics for this application.

By the way, the Vapor Bivy also has a zip-out bug screen.

[AK Hiker]

Try making your own bivy:
http://www.sixmoondesigns.com/ultralight/Projects/Pattern_Meteor.pdf

It is fairly easy to do and with the right fabric you can get the weight down less than the 10 ounces that the instructions say it weighs.

I made one with .8 oz nylon top sil bottom for $35. I made it without the zipper to save weight and the thing is great!!!

[Christopher May]

Thanks Kevin. I didn’t realize the BMW Vapor Bivy has a zip out bug screen. I checked out the bivies suggested by others and it looks like for me it is between the Soul Bivy and the BMW vapor bivy. Can you or someone else give me more insight into the difference between the Pertex and the Epic material and why you prefer the Epic. Also, you suggest asking Doug Johnson and Paul Johnson about there experiences with the Soul Bivy. Is there a way to ask a staffer like Doug Johnson a question or do I just have to hope he reads this post? Thanks.

[kevin davidson]

Pertex is a very nice tightly woven wind proof, water resistant, and very light fabric that comes with a high quality DWR treatment—which will eventually wear out and will have to be re-applied by the consumer ( it will last quite a long time,depending on how many times you launder it. It is my favorite sleeping bag shell material. Many people consider it an adequate material for bivys used in conjunction w/ tarps.

Epic has a life of the materia,l encapsulated silicon treatment (not to be confused for body enhancement materials!) that is highly water resistant almost to the point of being waterproof, It is also wind resistant and highly breathable—although not as breathable as Pertex. It is, in it’s “malibu” form,somewhat heavier than Pertex.
Epic will leak if it gets dirty but is restored by washing. It also will leak in the bivy bag format if a downpour lasts long enough. Epic cannot be taped so it has to be handsealed w/ a sealant. Not an issue for me because I use it in conjunction with a tarp. Some people have noticed that you can get frozen condensation within an Epic bivy in temps. betwwen 20 and freezing.

I like the Epic for it’s longterm water resistance and ability to use as a stand alone bivy if conditions are not too dire.

A pertex bivy can be made in the 6-7 oz. range. Epic, in the region of 8-9 oz.

The 2 Johnsons (!) hopefully will respond to this thread

Hope this helps.

[Author]

Posts