Saturday, December 24, 2016

Detaled sewing instructions for box underquilt with clew suspension

Are you curious about Leiavoia's neo-retro-innovation in hammock underquilt design?  Do you want to try making an underquilt that will accept a clew suspension and won't have compression-issues?

I took a stab at such a DIY project and I'm sharing detailed sewing instructions for the box underquilt that I made to fit a clew suspension.  Boxing the quilt is a universal technique and could apply to a conventional underquilt suspension (including a quilt with a secondary suspension). By including a side wall and box to the underquilt, the Climashieled Apex insulation is not pinched at the edges.  Because the suspension is attached to the upper part of the box, the insulation and shell fabric are able to hang between the suspension clews without getting squished.

Before you start cutting fabric, note that my pattern is for a person my size.  I am 5'6" and I don't have broad man-shoulders.  I made this quilt to fit me without extra fabric and insulation that will make it heavier in my backpack.  I know that this should go without saying, but if you are taller, make the quilt longer.  If you are broader, make the quilt wider.  Please think carefully about the size of the quilt that you need.  As you will see in my sleep report (in the video below), the underquilt is too small for my husband.  He is a 6' with a lumberjack body type, and he definitely would need a wider underquilt to prevent cold arms.

After troubleshooting this design a little, I figured out that when a total length for the quilt + suspension = 87.5% of the length of my hammock, I got a pretty snug fit without gaping, but I had to thread my hammock suspension directly through the descending ring.  This worked for me, but I can see myself shortening it up a little more in the future, especially if my shock cord starts to lose its stretch.  I suggest taking the length of the suspension + underquilt down to 85% and then putting a durable extender on each end so that it is adjustable in the field.

For a lady who sleeps cold, I would consider this 6 oz Climashield Apex underquilt a 30 degree underquilt.

Sewing Instructions:


What you will need for this project:
  • 2 1/2 yards Hyper D Ripstop Nylon (outer fabric)
  • 2 ½ yards Membrane 10 Taffeta Nylon (lining fabric)
  • 2 ½ yards Climashield Apex
  • Size 20 KAM Snaps (16)
  • 1” webbing, cut to 5” lengths (16)
  • Clew Suspension (click here for instructions)
  1. Fabric Cuts (note that seam allowances are 1/2" on each side, so fabric cuts are 1" longer and wider than the finished underquilt.  If you are making your quilt larger, account for the seam allowance when cutting):
  2. Outer Fabric:  Shell:  75” x 46” for body.
    b.      Outer Fabric: Side walls.
                                                        i.     2 at 75” x 3”.
                                                       ii.     2 at 46” x 3”.
    c.      Cut from the lining fabric 74”x 46.”
    d.      Cut from the insulation 74” x 46”.
    e.      Cut from 1” webbing 16 at 5”, seal edges with a flame.
    2.      Mark webbing pieces with a pencil 1 ½” from edge so that all are sewn the same length.  You will line this mark up with the edge of the fabric.
    3.      Attach side walls and webbing to lining fabric.
    a.      With right sides together, pin side walls to lining fabric with the ends meeting on all 4 sides. 
    b.      On both short sides, place 8 pieces of webbing between the pinned lining fabric and side walls so that the pencil mark is facing out of the fabric and is lined up with the edges of the fabric.  The first and last piece of webbing on each side should be 1” from the corner, and the remaining pieces of webbing should be equally spaced in between.  Tape or pin into place. 
    c.      Sew a basting stitch along all for edges with a ½” seam allowance.  Start and stop the basting stitch ½” from the edge of the corner.
    4.      Attach insulation to lining fabric.
    a.      With the side walls facing up, place the insulation beneath the lining fabric.  Pin every few inches on all 4 sides.
    b.      With insulation facing down, carefully sew the insulation to the fabric so that the needle follows the same line as the basting stitch.  Start and stop the stitching ½” from the edge of the corner to account for the seam allowance and stitching at the corner.  Take care not to sew through the loose edges of the webbing or the side walls when sewing.
    c.      Sew the loose (short) end of each piece of webbing to the inside of the side wall so with a reinforcing seam in the shape of an X.  Do not sew the X into the seam allowance for unsewn side of the side wall.  Trim off excess webbing.
    5.      Box corners: 
    a.      With right sides together, pin the edges of each side wall together and sew with a ½” seam allowance.  All three seams at each corner should meet and form a box at each corner.
    6.      Attach  outer fabric to quilt:
    a.      With right sides together, pin the edges of the outer shell fabric to the side walls, taking care to line up the corners.  Mark a space on the long sides that is 15” wide that will not be sewn (yet).  This will allow the quilt to be turned right-side out.
    b.      Beginning on the mark for the opening, sew the outer shell to the side walls on all for sides.  Sew in a curve at the corners so that you do not have sharp corners.  When sewing on the short sides, do not sew any remaining webbing into the new seam.  Instead, tuck the webbing out of the way and trim after sewing.
    c.      Turn quilt right-side out, smoothing all the seams and poking out the corners.
    d.      Pin the opening together so that the seam allowance is facing inward and sew a straight stitch to close.
    7.      Attach snaps to webbing and attach clew suspension:
    a.      Fold the end of each piece of webbing down 1/3.  In the center of the folded section, attach a KAM Snap cap on the outer side and stud on the inside.  In the center of the unfolded section, attach a KAM Snap cap and socket.  Fold over to snap.
    b.   How to weave the clew suspension with shock cord for the underquilt: 

Refer to these links for more information:
  • Leiavoia's blog post:
  • Leiavoia's hammockforums post:
  • Derek Hansen's blog post on the clew suspension:
  • Derek Hansen's youtube video on the clew suspension:
  • My blog post on how to weave the clew suspension with shock cord for the underquilt: 
  • My sleep report with troubleshooting the suspension


  1. Great instructional post! Do you mind if I share it with

    Take it easy,

    1. I am going to make the clew underquilt and plan to use a 60x70, 650 down-filled throw that only weighs 16oz. Would like your opinion about snapping two of these throws together and putting the clew snaps on the bottom one. This would allow me to use the two throws together in colder weather and remove one in more temperate weather. Your thoughts?

    2. Warren, I think you could Kam snap two quilts together. The Kam snaps are plenty strong. You might need to put some snaps in the middle to prevent sagging. Not sure, but it might be something to plan for. Good luck!

    3. I looked at the Amazon KAM kit for $15 and it has enough KAMs to do the project but they are size 20 KAMs (1/2" diameter) so should I get a wider grosgrain ribbon since your example calls for size 16 KAMs? Also, have you ever tried this design on a bottom entry hammock (Hennessy) before? Since I lay on a diagonal, I'll be doing the asymmetrical clew you pictured.

  2. I'm pretty sure I'm using a size 20 KAM snap, so a 1" or 7/8" grosgrain should be just fine. I'm excited to see what you come up with. Keep me posted!