Hammock/ Bivy
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Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Hammock/ Bivy on 06/04/2009 23:13:01 MDT Print View

For quite a number of years now I've been entertaining and drawing up the idea of a hammock that can double as a proper bivy. I really like the versatility that a hammock can add to the backpacking setup, but so often hammocks are quite a bit heavier than a good UL setup, with a lot of added weight simply to help keep the walker warm. I also do a lot of walking above tree line here in Japan and often it is difficult to drop below to safer altitudes, so I need something that I can easily and often use on the ground.

I've been thinking of making a hammock out of a double layer of Momentum, with gathered ends and a Hennessey-like slit running lengthwise halfway down the upper layer of the Momentum. This slit would allow me to slip between the two layers of Momentum and use the hammock as a water-resistant bivy. No-see-um netting would cover the upper portion of the hammock and be split in two at the ridgeline, opening like a Boston-bag and closing by hooks attached to the ridgeline. I'll use my Gossamer Gear SpinnShelter as the canopy; it's long enough and has closed ends. I can bring it to ground and have a stormworthy shelter.

I'm just wondering if anyone has used Momentum for a hammock material and what they would think of its strength. I'm worried that the 0.9 weight material might not be strong enough, though by doubling up it should be plenty strong.

Any suggestions?

Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Re: Hammock/ Bivy on 06/05/2009 09:47:21 MDT Print View

Bump! Surely there's someone interested in this?

te - wa
(mikeinfhaz) - F

Locale: Phoenix
Re: Re: Hammock/ Bivy on 06/05/2009 10:14:42 MDT Print View

hold your horses, mike!

momentum is, by my measurments, not .9oz. it came in on my gram scale at 1.1
others have complained of 1.2

just use 1.1 calendared ripstop with dwr. cost $5-8 a yard

i had no problem visualizing the concept as you describe it, thanks for that.
i am still trying to figure out if something like that could work for someone like me, but i dunno if it beats a plain ol' single layer mosquito hammock with a small tarp. at least with a good tarp im guaranteed a dry night. i do however like your idea. i dont have any constructive criticisms unfortunately.

what about epic? i think its for sale at Rocky Woods.

Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Re: Hammock/ Bivy on 06/05/2009 13:08:14 MDT Print View

I thought about Epic, (Ron Bell used it on his Epic hammock a while back) but thought maybe it wasn't quite breathable enough as a good tarp-and-bivy bivy.

Momentum is 1.1? Well, that's relief in one way, sort of a disappointment in another, in that it means the whole hammock/ bivy would by heavier.

te - wa
(mikeinfhaz) - F

Locale: Phoenix
cuben? on 06/05/2009 14:16:49 MDT Print View

you could try cuben, Bill has used it with some success... but it wont breathe so i would not try it. (then again, ccf wont breathe either)

says eric: "The Epic treatment also makes the fabric stronger. Ron Bell chose it for the hammock he made and mentioned that the fabric stretches more in one direction than the other which he used to good effect"

i dont know of anyone using it.. you could ask guys @ the hammock forums perhaps. about 3,000 members there.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Fabric weights on 06/05/2009 16:16:15 MDT Print View

> momentum is, by my measurments, not .9oz. it came in on my gram scale at 1.1

A common misunderstanding. In the rest of the world fabric is specified by its finished weight. In America fabric is specified by the base weight, before any treatments have been applied. A source of endless confusion. Also note that fabric weights are always approximate.

So 'silnylon' is said to be a 1.1 oz fabric, but when you weigh it you will find that it is more like 1.3 -1.4 oz per squ yd. The silicone polymer has been added. Momentum has a DWR treatment applied, boosting it from 0.9 oz base weight to about 1.1 oz.

A wee bit like talking about 'base weight' of a pack when you have all your warm clothing on your body!

Cheers

Gary Boyd
(debiant) - F

Locale: Mid-west
That's funny on 06/11/2009 19:49:01 MDT Print View

It's funny I had my Hennesey spread out on the floor this morning laying inside it thinking would this work? The answer I think is yes, if it weren't so darn heavy (Still under 2 lbs). I was going to strip the tarp from it but it weighs in over 9 oz, which I don't understand because it's awful small.

And maybe I'm missing something in the design but if you're going to have no see um top then you don't really need a breathable fabric do you?

Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Re: That's funny on 06/11/2009 20:09:50 MDT Print View

Well, noseeum is a lot more breathable than breathable nylon fabric and you can see through it, which makes it a little less claustrophobic. But you do have a point... it does just add weight. Thing is, mosquitos and black flies and midges are a notorious problem here in Japan and since the hammock/bivy will not work as a hammock with Momentum fabric unless the fabric is doubled up under you for strength, you have to have some kind of bug protection when in hammock mode. On the ground the bivy would not need the noseeum, since you'd be sleeping inside the two layers of Momentum.

Gary Boyd
(debiant) - F

Locale: Mid-west
Well what I mean is... on 06/11/2009 20:34:31 MDT Print View

I definitely see the point of the no see um, but why use an expensive DWR like Momentum when cheaper/lighter/more durable/ more waterproof fabrics are available. You don't need the bottom of a bivy or hammock to breathe, and since you have the no see um on top it will breathe wonderfully.

Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Re: Well what I mean is... on 06/11/2009 23:07:53 MDT Print View

That's what I thought when I made my first hammocks... but the fabric does need to breathe. When you're lying in a waterproof fabric your body sweats and condensation forms, especially if the ambient temperature is cold. Even with a breathable mesh top there is not enough breathing to stop the condensation.

I want to use Momentum because I need a water repellant bivy when on the ground. I also like to have a hammock body that is resistant to windblown rain when hanging.

If I can get the hammock right so that it serves as a useful bivy then I will have a very versatile system for hanging in the very steep mountains here in Japan... I can even hang on ground where there is no level camp site. I've sometimes walked for up to three hours looking for a level site to pitch my tent or tarp, and at the end of the day sometimes you just want to get to bed already!