Ongoing DIY: Complete Hammock System
So, my next project after I finish the alpha phase of my pack design is going to be a complete hammock camping system (no, I don't generally think small, why do you ask?), and I was looking for feedback from the collective pool of knowledge that everyone brings to this wonderful forum.
To begin, my priorities for the system (in order):
- Ease of Use
- Durability
- Cost
- Weight
1.) Ease of Use:
By this, I mean that it should be easy to set up and take down, with as little "fiddle factor" as possible. Testing will be required to hit the proper temperature ranges and weight ranges, but I think I have a good leg up on that due to the pool of knowledge available for data mining here on HF.
1a.) Modularity:
The system should be able to be scaled up or down as the weather changes, from clear skies and 80+ degrees F down to 0 degrees F and blizzard conditions. While it is unlikely that I will face the low end of that range here in FL, I may (probably will) want to go hiking and camping elsewhere on the east coast, and that may entail such conditions. So, I need to at least have a plan to add on to the system for those sorts of conditions.
2.) Durability:
The system needs to be able to stand up to a beating. I'm hard on my gear--always have been. So, it needs to be almost as tough as major-retailer gear, or easily field-repairable, or even both (my goal). This means that it's going to be heavier than most ultralight gear (which is fine: I'm not a thru-hiker, and I'm in reasonable shape for someone under 30).
3.) Cost:
This is the secondary reason that I want to go DIY rather than purchasing from retailers or gear makers (the first being that no one offers exactly what I want out there; most of the cottage industry folks have many, or even most of the things I want, but no single one of them offers all of those things). This will likely take care of itself over the long run, with trials and alpha testing winding up costing nearly as much as (or perhaps even more than) a complete system that is store-bought. However, it won't have the hidden cost of gear that I wind up being unable to sell. I can budget for this in the safety of knowledge that I will have to refine it somewhere down the line.
4.) Weight:
While I'm in the middle of finalizing my alpha design for my pack right now, I still don't want to have to carry more weight than is absolutely needed. As long as I can keep a five-day trip in three season weather (down to freezing) below forty pounds (20% to 22% of my body weight, depending on fitness level) from the skin out, I'll be okay. To be truly happy with the design, I'd prefer to keep that weight down to thirty pounds (15% to 17% of my body weight). Since I have an idea of what the rest of my gear is going to weigh, I can design around this requirement. Hopefully, compromises here will be few and far between; however, the three requirements above will win out if there is a tie.
Alright, enough jabbering. Time to get to the design phase!
Let's start with the simplest portion of the system: the hammock itself...
The Hammock: Initial Design of the Core Component
The first component of the system is the hammock body proper. Without that, the rest of it is nothing more than an extensive tarptent set-up.
I intend on using the DIY Gear Supply double-layer design (thank you, sclittlefield, very much, for making that design public!), with a few alterations.
Firstly, I'm going to make it a single-layer design out of 1.6, 1.7, or 1.9 ounce ripstop, since I intend upon using an underquilt system rather than a pad and I weigh 185 to 200 lbs. Secondly, I am going to increase the side hems to 1.5" to accommodate 1" Omni-Tape sewn to it without compromising the structure of the hammock body proper.
The Omni-Tape is intended to be the core of the modularity of the system. Everything is going to attach either to that or to the structural ridge line that runs the length of the hammock, with the exception of the tarp/poncho that I'm in the midst of finalizing the dimensions on. The Omni-Tape will be attached to the bottom of the hammock body, running 80% of the length of the body, to allow for a full-length underquilt and decent wind-blocking capability from the overcover/undercover combo while still allowing for venting at the head and foot ends.
Here, I run into my first question for the forum at large: does anyone have numbers for the force needed to pull Omni-Tape apart? I've done several searches on it and have come up blank thus far. I believe, based on nothing more than a couple of unscientific tests performed with JRB compression sacks and known-weight items, that one square inch of OT (both sides together, for obvious reasons) should be able to hold about 3 to 6 ounces in a straight pull and slightly more than that in shearing force. Any numbers that anyone has on this would be greatly appreciated!
My suspension system, in keeping with the ease-of-use dynamic, is most likely going to be a strap/buckle one. I may wind up buying a ready-to-use system from one of the retailers, since it isn't much in the way of savings to do it myself (and, if something is likely to fail catastrophically, this is the most likely spot).
Onward and upward: the tarp/poncho combo is up next...
High and Dry: Tarps and Ponchos Galore
The second-most important item in the design is the tarp. Heck, I live in Florida; we get six months of 3:00 PM thunderstorms like clockwork.
So, I've come up with the following design:
http://www.hammockforums.net/gallery...0100_thumb.jpg
It's an hex tarp that measures 12' 6" long by 10' wide. With the 1' 6" head slit at the middle, that should allow it to fold up to the dimensions of a standard USGI poncho.
At each corner of the tarp, I intend upon placing a mitten hook attached to grosgrain or gutted paracord loops. This will allow the tarp to attach easily to a separate CRL to be strung up before taking the poncho off. In addition, I can carry stakes with the lines already attached to clip the tarp to. This should minimize my time in the rain without a poncho and offer a semi-sheltered place to hang the hammock.
When wearing the tarp as a poncho, the mitten hooks will clip to loops attached to the head slit and to a pair of loops centered at the point where the hex cuts begin. This will pull the tarp in far enough to keep it from being too unwieldy, at least in theory.
My issues are as follows: the poncho/tarp is going to be heavy and bulky compared to a normal poncho, it is going to allow me to get wet setting it up, and it does not offer any end protection against wind-blown rain.
We'll see if this winds up being a valued piece of gear that helps lower my pack weight or a white elephant that I wind up hating in the field...
Silny Slugs: Carrying System/Weather Protection
In keeping with the ease-of-set-up dynamic, I intend upon using something like a cross between Hennessy's snakeskins and WL lazy slug tube as the carry system for the hammock and attachments.
If I make oversized snakeskins with drawstrings (probably made out of shock cord) at the midpoint, which are sized to handle maximum volume I expect out of the system in full winter mode, I should be able to use them as end weather protection against wind-blown rain.
For the poncho/tarp, I figure on using a standard waterproof (well, water resistant, since it'll have a drawstring closure rather than a roll-top) stuff sack that attaches to the tarp (haven't decided on just how yet) to go over the head slit, providing additional coverage to prevent water intrusion.
Hot Tail: Underquilt Musings
So, I'm in the midst of trying to figure out my underquilt design.
My current design has me using a modular design, composed of two, possibly three lightweight quilts that will stack. The first quilt (against the bottom of the hammock) will have a layer of stretchy material, two layers of IX (the InsulBright, while useful, has a tendency to not be the most durable of materials), and then a layer of 1.1 nylon. This'll be my summertime quilt.
A question on this for those of you out there with more sewing experience than I: how hard is it to sew a stretchy spandex or lycra material while its stretched out to its maximum?
My thought is that, if I sew it to the IX with the stretchy material at its maximum stretch, I can then rely on it to scrunch up when it's not under pressure and conform to the bottom of the hammock. Then, when my body weight stretches the nylon in the hammock, the inner layer of the underquilt stretches and stays with me. The real trick is going to be getting the outer layer of nylon and the two layers of IX the right size so as to not be compressed when the inner layer is at its maximum stretch.
I've searched the forums, and don't see any posts on anyone doing this. However, as always, it's possible I've missed a post somewhere. Does anyone have any experience with this approach?
Reprioritization, Redesign, Reuse
So, I've gotten into and past the basic design phase to actual Alpha testing. I had several priorities when I started this project; they've changed somewhat due to experiences that I've had on the trail. Weight has become a much more important factor for me since my Foothills Trail trip, mostly due to bitter experience with an heavy pack on that one.
So, with that in mind, I've gone over to some more conventional design aspects in places and some...less so.
Let's start with the hammock:
It's a standard 11 ft by 5 ft blank to start.
I roll-hemmed the long edges and then roll hemmed the short edges to make a channel for a Warbonnet-style whipping (I used braided mason's line here; it's lightweight and cheap, and the whipping does not depend on the strength of that cord).
Then, I sewed the loop portion of hook-and-loop (Velcro) to the hammock body along the long edges, over the hems. I started from each end of the hammock with 24" of 0.75" wide loop. Once that was sewed in place, I sewed an 80" long piece of 1.5" wide loop in between the 0.75" wide stuff, along the hems once again. This provides a secure anchor for my under insulation and allows me to use the bug net with my undercover/poncho (more on that later).
I then added 1/8" Amsteel loops, using a triple fisherman's knot to hold them together. I then larksheaded those to a pair of descender rings on each end and larksheaded the whole mess to the hammock whipping knobs. I sewed loops in the ends of 15-ft lengths of 1" polyester webbing (five bartacks, spaced 3/4" apart) and am using those as the suspension system for it.
Before attaching the head-end Amsteel to the hammock, I sewed up a BlackBishop Bag for the hammock and under insulation (my top insulation goes in another bag, but I find it convenient to have the bottom insulation ready to go). I then ran the head-end Amsteel through the button hole and larksheaded it to the hammock.
I then added the CRL. I did not use an exact measurement for this; instead, I hung the hammock in my front yard and lied down in it several times, adjusting the suspension length in between tests, to ensure the proper length. Once the hammock was at the proper length, I cut a piece of 1/8" Amsteel and triple half-hitched it to each whipping knob.
I then cut and sewed the bug net. I used DIY Gear Supply's dimensions for the zippered bug net that they give on their how-to page. Instead of using a zipper, however, I sewed 0.75" hook (the other half of the Velcro) to the netting at the edge. The only difference I made in dimensions was to leave 5" at each end instead of tapering to a point the way the directions show; here, I sewed 2.5" of hook and 2/5" of loop to the netting, to allow it to close over the Amsteel loops at the ends of the hammock.
After some field testing, I added shock loops (1/4" non-roll elastic, 4" long) to the netting, approximately six inches up from the long edge and 30" from the head end, to accommodate a stick as a spreader bar in order to keep the netting off of my face.
Next, I made the tarp. Again, DIY Gear supply came to my rescue. I used their ultralight asymmetrical tarp, since I was trying to save as much weight as possible. The only modification I made to it was to use LineLoc 3s on the guyline tie-outs, to allow me to adjust the tarp without leaving its coverage.
Finally, I made a poncho/undercover/Garlington Insulator. Here, I took a piece of 1.4 Sil, 60" wide before hemming, and cut it to a length of 90". I hemmed the long sides. Next, I hemmed the bottom, leaving a channel for 1/8" shock cord. I ran the shock cord, tying a stopper knot at one end and putting the other through a mini cord lock. I then cut a 10" wide slit for an head hole and cut a 12" long slit for a front vent. I added OmniTape (the non-stick Velcro) for 30" from the bottom hems up the long sides for a closure and suspension system. I then roll hemmed around the head slit to make a channel for a collar drawstring (this was actually the hardest part). I then added Omnitape to the 12" vertical slit that I'd cut and added a piece of 0.5" grosgrain at the bottom to keep it from expanding downward on the front of the poncho.
The poncho is also an undercover for the hammock; I pull apart the side closure OmniTape and then press that to the bottom side of the 1.5" loop on the hammock body. The shock cord on the short ends of the poncho get pulled tight to provide end closure against wind intrusion, and the bug net gets pressed against the top side of the loop to close that (thus allowing for mosquito protection even in pouring, gusty rain).
I tested that last night and this morning during the fringes of Tropical Storm Isaac, and I'm happy to report that it worked well. Without the undercover, the wind-blown rain would have soaked the hammock body on the windward side. With it, I didn't notice any wind-caused water intrusion at all; it all beaded up on the outside of the sil undercover and ran off. However, I did notice that I was getting water intrusion through the head-end Amsteel loop; the descender rings were outside the tarp's coverage and weren't acting as a drip stopper. Easy enough to fix, though. I just need to shorten the loops.
Drawings, photos, video, and weights will come later this week or next week. However, I'm happy with my progress so far, and field testing has brought some minor tweaks to my attention. The spreader bar was one of them; shorter Amsteel loops (to keep the descender rings under the tarp's coverage) are going to be another.
It's held up well in heat, humidity, voracious mosquitoes, pouring rain, and high winds so far. I'm hoping for some cooler weather some time soon to test the under insulation...
Long and Form-Fitting: First Layer of Underquilt
The inner of my modular underquilt design is a two-layer, full-length IX. I just tested this last night: it was a little less impressive than I'd hoped, but not terribly far off of my temperature expectations. It appears to be good to about 45* F with normal clothing for those temperatures.
Specs:
Length: 78"
Finished Width: 52", tapering to 25" at either end.
Raw Inner Layer Width: 52"
Inner Layer Darts: 4 x 6.75" W x 20.25" L per end
Raw Outer Layer Width: 56"
Outer Layer Darts: 4 x 7.75" W x 23.25" L per end
Attachment Method: 1.5" wide, full-length Velcro
Weight: 10.25 oz (this will increase when I add the next layer's suspension Velcro, probably by about 2-3 oz; will make a note of it when I do).
Temperature Rating: 45* F.
