Results 1 to 9 of 9
  1. #1
    New Member
    Join Date
    Oct 2014
    Location
    Northwest Montana
    Posts
    20

    R&D - "Mummy Hammock" distant relative of "normal" bridge, Only 1 or NO spreader bar, 2-4 trees.

    I've been experimenting for about a year now with different types of hammock styles, lays, suspension systems, and construction methods. Nothing done permanent just throwing stuff together trying to figure out a perfect set-up for how I like to hang and what is most comfortable for me. Often done on site at my camp sites.

    About two months ago I hit upon a way to hang a bridge style from three trees with one at the foot and two at the head and skipped the spreader bars hooking the two head ends to the two separate trees to keep the head end spread and just letting the foot end wrap around my legs and cocoon them without a spreader bar down there. Was the best and most comfortable up to that point but was still lacking in that my chest and buttocks still sunk too much and weren't fully supported and it still squeezed in on my shoulders a little bit.

    Been working on improvements on the idea in CAD and built my first prototype and tried it out this weekend and spent Friday and Saturday nights sleeping in the v1.0 prototype set-up on my own place. The prototype is not sewn together but is rather zip-tied every half inch or so along the edges using the same 2" fold over with the rope in its loop and a zip-tie through both layers of fabric and around the rope in its fabric loop set slightly loose so the rope can still move just like it would if a sewn in loop was used (quick way to prototype a bridge type set-up and doubles as a torture test on the fabric and clearly shows any over-stressed points):

    Test Pattern v1.0.GIFEdge Rope Channel.GIFTest Pattern v1.0 Primary Cut.GIF2610-182602.jpg2610-182613.jpg2610-182632.jpg2610-182642.jpg2610-182651.jpg2610-182716.jpg

    Test fabric used was a cheap $10 canvas drop cloth that already had been well worn and had a few torn edges and such but had enough good in the middle to cut out my test pattern. Test rope was some cheapest of the cheap hardware stuff that was like $8 for a 100-ft. roll and is basically the same thing as para-cord only in a big 3/8+ diameter, same stretchy white fiber core covered by braided outside covering. Had to pre-stretch the stuff to the tune of like 4-ft. stretching out to 5-ft. before it finally tightened up but once it did it worked well enough for a prototype test at my own place.

    My idea was to position my broad shoulders and upper chest at the widest and least constricted point where the single spreader bar would sit in a two tree suspension set-up or in a 3-4 tree suspension set-up as used is held open by the primary suspension lines in their triangle configuration. And then the mass of my buttocks (I've got a lot of muscle mass in my upper legs and hips more then the average male and have trouble getting pants that fit right because I've usually got multiple inches to spare around the waste by the time I get a large enough size so that it isn't skin tight around my upper leg muscles) is supported by the aggressive bridge curves. Thus the idea being to provide the most support exactly where it is need on the two points that normally sag and sink even in a normal bridge hammock set-up and to have my wide shoulders that I don't like getting squeezed from the sides right at the widest point where I get the most shoulder room and to a certain extent some elbow room as well. And then to have my head supported by the upper triangle section with its single top point so that I can tighten up that point to raise my head like a pillow or lower it as desired to get my lay exactly like I want it.

    Well, it worked out great for improved supporting my chest and buttocks and not having them sag and sink and the no squeeze on the shoulders with plenty of shoulder room worked out great as well. But I had a problem with the head triangle which wanted to pull my head up way too much unless I really loosed up the support at the top and letting the entire head triangle area sag way down which is not what I wanted since I wanted the hammock to fully wrap around me so I started cutting zip-ties starting at the top point support of the head triangle and working back up each side of the triangle. Got almost no release in the tension that was holding my head up too much until I got to the mid-point on each side of the head triangles sides and then the tension released very quickly with the cutting of just a couple ties on each side. So it was the middle of the head triangle sides that were creating too much tension and pulling my head up too much in the triangle not the tip of the triangle which I could still pull up to touch the rope junction point at the top tip without pulling my head back up too high again. Realized I had created basically a mini-gathered end like upwards tension pull in the center of those triangle sides and modified my pattern accordingly to provide 8" of extra material length to relieve those unintended tension points by cutting an outward bow shape rather then a straight line:

    Test Pattern v1.1.GIFTest Pattern v1.1 Primary Cut.GIF

    Couldn't find another piece of appropriate junk material to make a v1.1 prototype today. Will have to pick up another cheapo drop cloth tomorrow. If that alteration to the cut pattern fixes the head triangle issue I had with the v1.0 then along with some doubling fabric reinforcements in some higher stress points that showed up in the test I should be able to work towards and actual permanently sewn version. Got a nice 58" x 3-yard piece of heavy hemp canvas and some 1/2" diameter 2,000-lb test quality Manila rope I've collected that should work perfectly for an all natural high strength built to last hammock. Obviously won't be light weight but when your going into the back country with horses weight isn't as big of a deal and you pack by the pound not by the ounce.


    P.S. = Those pictures of the hammock are after I cut some of the zip ties in the head triangle to relieve the tension that was holding my head up too much in the upper triangle and after I had spent two nights sleeping in it to test it out. The black background are CAD screen captures that have been cropped.
    Last edited by turbo1889; 10-27-2014 at 03:12.

  2. #2
    Senior Member WV's Avatar
    Join Date
    Feb 2008
    Location
    southeast WV
    Hammock
    DIY
    Posts
    4,815
    Images
    208
    It's nice to see really creative work in progress.

  3. #3
    Senior Member miyanc's Avatar
    Join Date
    Aug 2012
    Location
    nc
    Hammock
    Work in Prog
    Posts
    2,583
    Images
    35
    Looks good. I wonder how a lesser fabric will hold in a few places. I also wonder how it works if you turn on your side?

  4. #4
    New Member
    Join Date
    Oct 2014
    Location
    Northwest Montana
    Posts
    20
    Quote Originally Posted by miyanc View Post
    Looks good. I wonder how a lesser fabric will hold in a few places. I also wonder how it works if you turn on your side?
    As to a lesser fabric holding up:

    The main high stress point that I have to reinforce is the fabric at the two outer triangle points where the rings are where the single spreader bar goes in a two tree hang or is held open by the tension of a 3-4 tree hang. Going to try a few different options to address that issue and see what works best.



    As to how it works if you wanted to sleep on your side:

    I normally like to sleep flat on my back staring up at the stars with as flat of a lay as possible so I didn't try that position. But, I went out just now and tried it as well as laying face down on my stomach. I would say that the upper and mid body support was as good or better then a normal bridge hammock for those positions. However the foot end doesn't work very well with the feet laying sideways. So the problem with laying sideways is at the foot end.

  5. #5
    Senior Member Redoleary's Avatar
    Join Date
    Feb 2009
    Location
    Pennfield Twp, MI
    Hammock
    DIY gathered end
    Tarp
    Hinterland gear
    Insulation
    down bag
    Suspension
    strap & E.T.'s
    Posts
    3,910
    Images
    70
    That is very intriguing, looks like a lot going on there, but it's a very interesting design. Would you guess that the compression on the spreader bar is the same as a normal bridge?? It seems like it would be very high but I don't really know why I think that.
    Good luck,
    RED

    My Youtube Channel

    Deep peace of the running wave to you.
    Deep peace of the flowing air to you.
    Deep peace of the quiet earth to you.
    Deep peace of the shining stars to you.
    Deep peace without end to you.
    adapted from - ancient gaelic runes

  6. #6
    New Member
    Join Date
    Oct 2014
    Location
    Northwest Montana
    Posts
    20
    Quote Originally Posted by Redoleary View Post
    . . . Would you guess that the compression on the spreader bar is the same as a normal bridge?? It seems like it would be very high but I don't really know why I think that.

    My quick rough and dirty math (but based on solid static load analysis) says the compression on the spreader bar should indeed be higher then on the head side bar of a normal bridge hammock, but should not reach much less exceed twice the compression loads on the head side spreader bar of an equivalent normal bridge.

    I intend to usually hang with more then two trees which means no spreader bar will normally be necessary. But when I do have to hang with only two trees and a single spreader bar I intend to scrounge up an appropriate chunk of wood on site that is a nice big 2"+ diameter and cut it to length with dulled points on each end to pin it in the metal rings on each of the primary load corners under load stress. Already had experience doing that with normal bridge style on previous camps this summer and it works fine. I'll just have to be sure to find a good size diameter one.




    I just finished putting together the v1.1 prototype and just checking this thread before I go to sleep in my regular bed since I pulled down the v1.0 earlier today because I needed the rope out of it. Way too late and tired right now to stumble around in the dark to hang the v1.1 prototype I just finished and I want to double check it when I'm not tired before I hang it anyway. This one since I had to spend $10 for a fresh drop cloth for material I took the extra couple hours to actually sew it. I don't have my own sewing machine and instead use the services of a local seamstress who has a heavy duty industrial machine and I get along with great and has done a lot of good work for me at a price that is way more reasonable then dropping a few grand to get my own industrial machine (I usually design cut and pin everything together so all she has to do is run it through her machine). So its hand sewn, big needle with doubled up high strength hemp cord running the simplest and fastest single needle single sided fast long stitches. Just did it while watching a movie, not the kind of hand stitching that one shows off by any means, the kind in fact that will give professional leather and tack guys migraines just to look at but its stronger then the zip-tie method of quick prototyping even with the long stitch lengths and is significantly more permanent. Basically so long as this v1.1 prototype works out to fix the problems with the v1.0 I should be able to keep the prototype around as a backup or guest hammock which was worth the little bit of extra effort and time since it has an extra $10 in it anyway.

    Will string it up some time tomorrow. Will post an update accordingly most likely with pics. See yu-all then.
    Last edited by turbo1889; 10-28-2014 at 04:14.

  7. #7
    Senior Member sr1355's Avatar
    Join Date
    Aug 2010
    Location
    Jackson, MI
    Hammock
    DREAM HAMMOCK
    Tarp
    UGQ H11/12 WD11
    Insulation
    UGQ TQ/UQ
    Suspension
    Whoopies w/ ET's
    Posts
    2,553
    Images
    103
    Very out of the box, have you thought about making the channels where the rope runs a structural hem instead? Would reduce amount of suspension required and provide a rigid fixed edge to the hammock possible evening out tension through the sides of the hammock.
    Happy Hangin'

    Paul - Master Fabric Welder @ UGQ

    >>>VISIT UGQ OUTDOOR HERE<<<

    [SIGPIC][/SIGPIC]

  8. #8
    New Member
    Join Date
    Oct 2014
    Location
    Northwest Montana
    Posts
    20
    v1.1 Prototype = Success !!!


    2810-134109.jpg2810-134132.jpg2810-134142.jpg2810-134200.jpg2810-134220.jpg
    2810-134300.jpg2810-134321.jpg2810-134417.jpg2810-134436.jpg

    Adding the 8" of curve to the sides of the top triangle on the pattern successfully relieve the tension that was uncomfortably lifting my head too much in the upper triangle (reference first post for further details) but I also added a supporting under-strap that takes a lot of tension off of the cloth fabric. The strap is 2" seat-belt grade certified webbing (I've got a big 300' roll of the stuff in my stockpile) and is sewed into the cloth such that its length is 2" longer then the virgin canvas material was so you have to get 2" worth of side to side stretch out of the fabric loading it down partially before the under-strap tightens up and takes the rest of the load. Which makes it so you can hardly feel the under-strap in your back and you still get that nice hammock feel in the support. You don't feel the under-strap unless you lay in the hammock with just a T-shirt and think about it and try to feel it and then in the proper position just sliding and inch or two back or forth you can get it right under your shoulder blades where it actually feels good not bad.



    Here is a close up of the "doubled high strength cord, single big needle, single-sided, fast, long stitch" hand sewing work I was talking about:

    2810-124814.jpg2810-124836.jpg

    I used 1-mm diameter tight spun natural hemp cord, stitch lengths are nearly a 1/2" long and not pretty nor consistent. But it gets the job done quick and it will hold up fairly well for quite a while. Should be enough for this prototype to serve as a backup/guest/loner/buddy hammock.

    Got other stuff that's more important to do right now that's got to get done today so I won't get to testing it in 2-tree with single spreader bar configuration today but expect that test and more photos some time later this week.

    If that all works out well, then I start cutting the pattern out of my good expensive hemp canvas and getting it all pinned, prepped, and ready to take to the seamstress I use to sew it up for me on her industrial sewing machine for the final version which I intend to have under quilt and top quilt insulation sewn right into the hammock as a permanent part of it so the mummy hammock is a mummy sleeping bag and the mummy sleeping bag is a mummy hammock. An all in one, single piece unit that just needs a rain cover tarp over it.

  9. #9
    New Member
    Join Date
    Oct 2014
    Location
    Northwest Montana
    Posts
    20
    Quote Originally Posted by sr1355 View Post
    . . . have you thought about making the channels where the rope runs a structural hem instead? . . .

    Not sure what you mean by that suggestion. Are you saying just fold the fabric hem on the edges over itself several times to build up a multi-layer thick hem and then sew it together so there is no rope or strapping on the edges and just the rolled up hem itself takes the suspension loads? Or do you mean using tubular strapping rolled in the hem and sewn in like often done to build normal bridge hammocks?

    As I have it now there is a single piece of rope that loops around the entire perimeter of the hammock with metal rings in the four corners to hook the suspension lines too. I like the "style" of using rope that way in a fabric loop hem but am certainly open to the idea of other options as well but will probably still go with the rope for "style" reasons. For my final version I intend to use more expensive high quality natural fiber manila rope which when combined with the heavy hemp canvas definitely has a "style" statement.

  • + New Posts
  • Similar Threads

    1. "Jerry Chair" and "Just Jeff Gear Hammock" combo - is it possible?
      By Bad Biscuit in forum Do-It-Yourself (DIY)
      Replies: 1
      Last Post: 11-03-2014, 13:09
    2. short 6-8" "spreader bar" help or hurt?
      By cdesmet52 in forum Claytor Hammocks
      Replies: 17
      Last Post: 12-28-2012, 23:07
    3. FS - 0°F Bag - "W", "L", Synthetic, Mummy
      By millergear in forum [SOLD/WITHDRAWN] Items no longer available
      Replies: 2
      Last Post: 11-27-2011, 11:42
    4. Replies: 2
      Last Post: 10-13-2010, 22:48

    Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •