Byer Hammock-radical conversion
1. Make a DIY hammock that is comfortable. My approach is to use a suspension that allows a lowered footbox. I will also work to acheive a flatter spread through the shoulder area.
2.Keep the weight about equal to the hammock system now in use. While not losing any functionality (bugnet, pockets, etc.) Any weight increase will need to be justified by additional warmth, comfort, or convenience of use.
I have started with the Byer Mosquito Hammock and made a conversion to a bridge styled hammock. The materials of the hammock; nylon body, netting and zipper were utilized. It may have been cheaper or more convenient to start with the Byer hammock rather than buy these materials, but not by much. Another small advantage was that the hems on each end that the original suspension lines were attached to, were useful for inserting webbing for my end caps. But here again, the time savings compared to starting from raw materials didn't amount to much in relation to the overall work involved.
The suspension design benefits from the long thread on Bridge Hammocks by Grizzly Adams. However, this project explores a pretty radical departure regarding connection of the hammock body to the lateral lines.H3_profile_ sansridgeline.jpg
This photo shows the body shape. bryer-newshape.jpgNote the orange lines, the material was later cut at those lines (and reattached later). This created a bilaterally symmetrical shape which was easier to work with- less confusing. Notice the four strips of webbing running across the width. The top webbing is at the neck line, the bottom webbing is at the knees, and the middle two are positioned above and below the butt. The idea is additional reinforcement and for more comfortable contouring in the drape of the hammock fabric. The part that extends beyond the yellow tubular webbing gets trimmed off later.
The yellow tubing is only at the edge of the material in the center portion of the hammock body. At both ends the webbing begins to veer out wider, while the cut of the fabric is becoming wider still. The tubular webbing stops about 8" before the top of the hammock and stops at the other end over 18" before the bottom hammock edge (foot). This webbing is just over 40" long and is the only area that is rigidly attached to the lateral support lines. A 10" portion of this is detached from the lateral support lines in the area of the shoulders. This creates two good billows that expand around the shoulders- very effective.
In this drawing, you can see the rope has been drawn with yellow highlighter.support_structure.jpg This illustrates how it weaves in and out of the hammock body and does not form a full length rigid attachment to the lateral support webbing- as other bridge hammocks use. This is the key to freeing the footbox to angle down slightly. A side benefit of this design approach is the lowering of the spreaderbars- essentially by raising the middle. This comes at a cost, by having the effect of reducing stability. One way of compensating for that is to make the head spreader bar wider and the foot spreader bar shorter- which I have done.
To give supportive structural attachment to the hammock ends that hang out past the rope/webing attachments webbing loops are used. webbing_circle_ends.jpgThey encircle each end cap and are also attached to the lateral lines, but in a way that allows some movement as tensions get distributed. The webbing inserts easily in to the factory sewn hem at the ends. I rolled the hem back over itself and sewed a seam creating a hem loop of double material thickness for added strength.
Bug Netting:H3_profile_ ridge_open.jpg
In an attempt to keep the netting area as small as possible, while not becoming difficult to use the factory provided zippered access, I installed two elastic cords stretching from knee to neck. They form lower netting panel insertss nearly 6" tall. But only when the hammock has weight in it, do the netting panels fully raise up on the sides (similar to the sides of a child's playpen). elastic_crib_detail.jpgThis serves to keep things contained, but it also is designed to take tension off of the zipper when operating from the inside when the hammock is occupied.
I was pleased with the implementation of the 18" aluminum tent pole at the head end of the netting. H3_head_entry_closed.jpgIt keeps the fabric away from my face while keeping the profile low. A side benefit makes it easier to twist the netting out of the way when entering the hammock.
The closed off foot box allows me to extend two elastic cords in opposite directions to become ridgeline segments. Both attach to the carabiner used to hang the hammock ends- keeping setup more simple. When taking the hammock down, each ridgeline segment is used to wrap the rigging at either end to prevent tangles between setup times.
The hammock is lined on the inside with wickaway fabric. H3_head_entry_open.jpgIt is very stretchy and feels like a high-tech t-shirt material. It serves as a sleeve for my pads (I have the Down-To_Earth closed cell- 4.2 ounces , I have an InsulMat Max Thermo open cel- 19 ounces, and a Stephensen's DAM- 26 ounces; to give a wide spectrum of comfort ranges).
So, how well did I achieve the project goals?
1.Comfortable? Yes! It is very supportive and comfortable. However, it is slightly less stable as compared to a HH ULBP (especially noticed when operating the zipper from within). This will need to be worked on. Perhaps part of the solution will come with experience, when I find the optimal tension and tree distance for instance.
Fully Functional? I believe so. The bug netting is working and it's an economical design weight-wise. I will have to see if it feels too confining. I knew that the netting had to flex with the hammock in order for a zipper closure to work very well. In fact, there are two places where the zipper needs to have the fabric held (reducing the local surface tension by hand) for it to close smoothly. These are the places where the zipper makes a big turn twards the midline of the hammock.
2. Weight comparison. My total weight with the straps and a lightweight poncho/fly is just under 3 pounds. The hammock is 2 pounds. and 1 ounce without the fly and straps. Since the liner that holds the pad is integrated in my hammock, it is only fair to compare against the HH ULBP with SuperShelter. Total weight of HH (with Snakeskins and SS) 2 pounds 15.4 ounces. That is about 4 ounces less than my hammock when used with the DTE closed cell pad. And although my new configuration is at least as warm (with the included liner) as the HH with SS. Still I would have to conclude that the weight goal has not been fully met. I do have a few ideas for the next one though...
Would I recommend this conversion project? Only if you have an extra hammock and lots of patience. More importantly, look at the suspension ideas and see if any of them will help you.
BTW making a hammock has been my very first sewing project. It did, however, take me 3 tries to get it to an acceptable level. So be encouraged when you take on your next DIY project. If I did it- you can too.
Last edited by dblhmmck; 09-12-2007 at 00:03.. Reason: sentence coherence
thanks for the pictures and documentation. One of the things I have to deal with inside my HH are my knees, I have to put some kind of padding/pillow under them. Looks like you've structurally dealt with this nicely.
How does it feel if you curl on your side some...now the webbing under-support is up against your side...
The webbing loops at the ends look like they have 4 small loops coming off of them, at the "corners". I see what the upper ones are doing. What are the lower ones doing?
I like very much the notion of modifying an existing hammock to change the suspension. I've been harboring similar thoughts, but don't know when I'll have the time to explore them (and no doubt destroy perfectly good hammocks in the process).
BTW and for the record, a correction related to your comment about me and the Bridge Hammock thread. It started with sort of idle chit-chat about the up and coming JRB Bear Mountain Bridge Hammock. Picked up speed some after the JRB rig was spotted in the wild at Trail Days. Took off when a guy named TeeDee started building one, and documented throughout different steps he took. I got involved around then because I liked the promise of sleeping on my stomach and/or side, and developed a well deserved reputation for being a math monster batting around analyses of forces with TeeDee and to a lessor extent Blackbishop. Scott followed with his prototype, and I started tinkering too. TeeDee left the forums, deleting all his posts on the way out the door. After 2-3 days of stunned, "huh, what's that about?" the thread picked up again, with a disproportionate number of postings by me. The point is that someone whose history with the thread starts after TeeDee's departure probably does not see the influence that he had on it. It is very large.
for the record, in the putting credit where credit is due department
very glad to have you contributing. Your ideas about shaping the hammock body to achieve certain comfort goals are really interesting.
Lower loop attachment thoughts
At the head end, 2.8 Spiderline rope connects from the outer pole attachments through the LOWER loops of the webbing. The upper webbing loops connect onto this rope with elastic cord (only). Elastic cord also goes between each of the lower loops and it's closest pole end (diagram will follow). The objective here is to allow the bottom of the head end loop a modest maximum distance of downward extension- that will still slightly cradle the back of the head. The elastic attachment to the upper loops (in addition to the longer length of these upper loops) allows the upper edge of the hammock's head end to dip slightly below the level of the hiking pole (staying flatter with the body while using minimal fabric).
A slightly different arrangement at the foot. Here the UPPER loops extend out to the main lateral ropes. They have a length of spiderline rope firmly attached at each pole end. But there is also elastic between those same attachment points which will only stretch to the point of full rope extension when occupied. The lower loops are connected relatively loosely to the hiking pole ends with elastic cord. The reason for this is that I want the foot box to be allowed to hang a bit lower and create a spacious area for the feet.