How to Hang a Hammock Underquilt (and Fix Cold Gaps)

An underquilt is the warmest way to sleep in a hammock — but only if it's hung right. The most common complaint we hear is "my underquilt was cold," and nine times out of ten it isn't the quilt, it's the hang. The good news: once you know the handful of things that actually matter, setting one up takes about a minute. Here's exactly how we do it — the same guidance we give customers who call us to get dialed in.

What you need

• A hammock underquilt (see JRB underquilts).
• The included underquilt suspension — shock cord and micro-carabiners. Most JRB underquilts come with it; for a spare or replacement, grab the Underquilt Suspension System. Use the included kit only — no extra clips (more on that below).
• Your hammock, hung the way you normally sleep.

Setting it up: five steps

1. Hang your hammock first. Set it at your usual height and sag. The underquilt follows the hammock's shape, so get the hammock right first.
2. Shake out the quilt. Give it a good shake to redistribute and loft the down before it goes on — compressed down needs a minute to reach full thickness.
3. Attach it with the included suspension — and nothing else. At each end of the hammock: fold the suspension cord in half and attach it to the hammock's suspension line 6 to 12 inches from the end of the hammock; loop the cord around the suspension line near the end; then set the length by tightening or loosening that loop near the end of the hammock. Finally, clip the micro-carabiners to the grosgrain ribbon loop at each corner of the quilt. That's the whole system — don't add clips or a second suspension. Our quilts are built to hang dynamically and conform to you; extra clips or a secondary suspension bind the quilt and make it sag, which is exactly what opens cold spots. (The illustrated steps are also on the card that ships with your quilt, and there is a setup video on our videos page.)
4. Set the tension against the empty hammock. Adjust the suspension so the underquilt gently lifts the center of the hammock when it's empty. That's your baseline: snug against the underside with the down fully lofted.
5. Get in, then seal the ends. Climb in, settle into your normal position, and pull the end cords just enough to draw the quilt in around your shoulders and feet. Snug, not tight — over-tightening creases the quilt and channels cold air.

Which side faces the hammock? On our dedicated underquilts, the black side goes against the hammock. On Dark Olive/Orange quilts, the orange side faces the hammock.

If your quilt has the foot-end centre-pull drawcord, pull the cord from the centre and clip its micro-carabiner to the suspension cords at the secondary hitch — where they loop around the hammock's suspension line at the end of the hammock.

That's it. Once it's set, it stays set — you can climb in and out all night and it holds.

Check the hang with a friend, in the backyard, the first time

Setting up an underquilt for the first time is best done at home with someone to help — not in the dark on the first cold night. Have one person get in the hammock while the other checks the hang from outside.

Slide one hand between the underquilt and the hammock and feel for air gaps. With the other hand on the outside of the quilt, check that the down is at full loft. Make suspension adjustments in half-inch increments, first at one end and then the other, until there are no gaps and the loft is full with someone in the hammock.

Once it's dialled in, leave the suspension set. Next time you only have to connect the corners of the quilt, draw the end cords, and fine-tune.

The one rule that fixes most cold underquilts: stay below the top edge

If you take one thing from this guide, take this: keep your whole body below the top edge of the underquilt. If a foot, shoulder, or elbow rides up over the edge, it pushes the quilt down and opens an air gap right there — and that's your cold spot. Here's the sneaky part: when you climb out to see what's wrong, the quilt snaps right back and looks perfectly set up. The gap only exists when you're in it.

So if you're waking up cold at the feet, don't start with the suspension — check that your feet aren't poking over the foot edge. A too-tight foot cord is a common culprit: it pulls the edge down so your feet slide above it. Back the end cords off, get in, and then snug them just enough to seal the ends.

Too loose vs. too tight — and why ours is more forgiving

Classically there are two ways to hang an underquilt wrong:

• Too loose leaves an air gap between the hammock and the quilt — cold air fills it and you get a cold spot.
• Too tight draws the inner and outer fabric together so the down can't fully loft, which drops the quilt's effective rating. (It takes about 2.5″ of loft to hold 20°F; squeeze that to 1.5″ and you're closer to a 40°F quilt.) Cranking it tight can also let a shoulder or hip press through and flatten the down right where you're lying.

That's the "Goldilocks" trap most underquilts have — not too tight, not too loose. Our dedicated underquilts engineer most of it out. The Mt Washington and Greylock — our purpose-built underquilts, optimized to be the best available — use a dual differential cut: the inner and outer fabrics are cut to different sizes and assembled so the outer shell is never pulled tight, which means the down lofts fully no matter how you hang it. Curved baffles let the quilt wrap around the hammock widthwise without creasing. Together they turn "not too tight, not too loose" into simply hang it snug — you don't have to fear over-tightening. (We also don't taper these underquilts; a tapered foot can look lighter, but it makes a proper hang harder.)

Dialing in the fit

Side gaps: a well-shaped underquilt wraps the sides — on the Mt Washington and Greylock, the dual differential cut and curved baffles do exactly that; if a side pulls away as you shift onto the diagonal, snug that end cord until it tucks back around you.

Foot end: make sure the quilt extends past your feet and — say it with me — keep your feet below the edge.

Head end: pull the top up around your shoulders; shoulders are a classic cold spot because they're wide and press hardest into the fabric.

Width: about 48″ is the widest an underquilt can go before it starts draping away from the hammock and making gaps. Our Mt Washington is 42″, but its dual-differential, curved baffles make it behave like a much wider quilt — our owner (6′3″) runs the Mt Washington 3 on everything from 10′ and 12′ gathered-end hammocks to bridge hammocks.

Bottom-entry Hennessy Hammocks

A Hennessy with the bottom entry slit needs a few extra steps, and they are worth getting right — the slit is where drafts come from.

1. If you are using The Nest or the Winter Nest, align the quilt's slit with the entrance slit on the hammock before you set the suspension.
2. Pass the hammock's asymmetric corner tie-outs through the loops on the side of the quilt. If you stake that corner to the ground, use the inner loop; if you tie out to a tarp corner or to a tree closer to the horizontal, use the outer loop.
3. On cold nights, don't stake the asymmetric corners at all. Let the hammock and quilt wrap in around your body instead — it is warmer.
4. Attach the hook-and-loop on the quilt's slit to the hook-and-loop on the hammock's slit.
5. Draft coming through the entrance slit? First check the quilt isn't caught in the slit — that is usually the cause. If it persists, seal the two legs of the quilt partially together to close the slit off; a few inches of Omni-Tape down from the crotch is normally enough.

A universal underquilt also works on a bottom-entry Hennessy — you push it aside to get in and the dynamic suspension snaps it back. The Nests are simply the no-fuss version, shaped for the slit. See Underquilt Fit by Hammock, or watch Hanging a Nest on a Hennessy Hammock.

Bear Mountain Bridge Hammock

A bridge hammock attaches differently — to the rings rather than along the suspension line — and once it is set, the only adjustment you ever make is tightening or loosening the end cords.

1. Fold the suspension cord in half. Pass the folded end through the outermost ring of the hammock suspension strap and drop both micro-carabiner ends through the loop. Cinch tight to form a girth hitch on the ring.
2. Pass one micro-carabiner through one of the hammock's corner rings, and the other through the opposite corner ring.
3. Pass the grosgrain ribbon corner loop on the hammock through the corner loop on the quilt.
4. Clip the corresponding micro-carabiner to the hammock's grosgrain ribbon loop.
5. Draw the end cord in about 4 inches, or until the end hem of the quilt lines up with the end seam of the hammock.

"It can't be this simple" — why the suspension is a shock cord and two carabiners

Two questions come up constantly:

“Seriously, is a shock cord and 2 carabiners gonna work… It can't be this simple.”

“Why don't you include a secondary suspension?”

Yes, it is that simple — and no, a secondary suspension isn't necessary on a JRB underquilt. It can actively work against a good hang.

We tested several suspension designs back in 2004. The clear winner for full-length underquilts was an elastic end suspension. A few years later, designing our first partial-length quilt, we found a channel suspension was the right answer for that shape — and the two have stayed that way ever since.

Four reasons the elastic end suspension won for full-length quilts:

1. Simplicity
2. Light weight
3. It works on any hammock
4. It lets the quilt move with you as you shift around in the hammock

Why full-length quilts use end suspension — and Greylocks use a channel

All our full-length underquilts (and multi-function quilts) hang on a dynamic end suspension — shock cord at the head and foot only. A full-length quilt already covers you end to end, so there's nothing to reposition: the end suspension keeps it snug, lets it conform and move with you as you shift, and saves the weight of extra cord. That elastic give is the point — never rig it static, because a rigid clip or tie can't take up slack as you move, so the quilt drapes, sags, and gaps.

You may see other makers sell a "secondary suspension" as an add-on. That's really just an end suspension — and they need it because they built a full-length quilt on a channel suspension. A channel runs cordage through the length of the side hem, which lets the quilt slide along the hammock. On a full-length quilt the ends then slide toward the middle overnight, the quilt sags away from the hammock in the centre, and that is your cold spot — so a second suspension has to be bolted on to hold it in place. There's a second catch: all that perimeter shock cord adds more weight than you'd think — cord is far heavier than down and light shell fabric, so it piles on ounces without adding a degree of warmth. We start our full-length quilts on a dynamic end suspension, so they never drift, there's nothing to bolt on, and we're not carrying the extra cord. Adding a secondary suspension to one of our full-length quilts can actually make the quilt drape and fall away from the hammock, opening the very air gap you were trying to close.

Our Greylock 3/4-length quilts are the deliberate exception: they use a channel (perimeter) suspension. A torso-length quilt has to be positioned along the hammock to cover your core, and the channel lets you slide and set it exactly where you want it. That perimeter shock cord isn't free — it adds more weight than you'd expect — but on a torso quilt the ability to position it is worth the trade. A full-length quilt doesn't need that along-the-length adjustability, so we don't carry the extra cord. Right tool for each length. Jack walks through the quirks of channel suspensions, and how to work with them, in Greylock Hang Tips.

Troubleshooting a cold underquilt

Quick answers

Do I need a special underquilt for my hammock? For most gathered-end hammocks (ENO, Warbonnet, Dutchware and the like), a universal underquilt fits. Bottom-entry Hennessy Hammocks are the exception — see Underquilt Fit by Hammock.

Can I run an underquilt and a pad together? In genuinely extreme cold, some campers add a pad inside as a backup layer. For normal conditions the underquilt alone is warmer and far more comfortable.

Should I add clips to keep it from sliding? No — that's the most common mistake. Extra clips and secondary suspensions bind the quilt and cause the very sagging and cold spots you're trying to prevent. The dynamic suspension is designed to move with you; let it.

Cold-weather tips

• Pair it with a top quilt. The underquilt handles everything below you; a top quilt handles everything above. Together they seal you in a full cocoon of loft.
• Block the wind. Wind moving under the hammock is the fastest way to lose heat. Pitch your tarp lower and closer in cold or breezy conditions to create a still-air pocket.
• Give the down time to loft. Pull the underquilt out early and let it fluff fully before bed.

You can't overheat — so size up

One more reason not to stress about the perfect summer-weight underquilt: you can't overheat from one. An underquilt warms only your back; the rest of you stays open to the air, so there is no sealed pocket to trap heat the way a sleeping bag does. On a warm night you simply vent from your top quilt — there's no "too warm" penalty from the bottom. That's why we tell people to size up to the colder rating when they're on the fence. A 0°F underquilt on a mild night is just cozy; an under-rated quilt on a cold night is a problem you can't solve from inside the hammock. Our Hammock Underquilt Temperature Guide walks through picking the right rating.

Ready to hang one?

Every JRB underquilt is handmade in the USA and ships with the suspension you need to hang it in about a minute — and on our Mt Washington and Greylock underquilts, the dual differential cut means you don't even have to fuss to get it right. For a visual walkthrough, see the setup videos on our videos page; if you're still choosing, the Best Hammock Underquilts guide breaks down the lineup by temperature and hammock type. When you're ready, shop hammock underquilts → and set yours up right the first time.