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
- 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.
- 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.
- 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 about 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 on the card that ships with your quilt and in our installation instructions.)
- 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.
- 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.
That's it. Once it's set, it stays set — you can climb in and out all night and it holds.
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.
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 lets the quilt slide along the hammock's length, so on a full-length quilt it drifts toward the center overnight and leaves your head and foot ends cold; the bolt-on end suspension is there to stop that slide. 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. (It's also why adding extra clips to a JRB quilt backfires: you'd be solving a problem ours doesn't have, and binding the quilt in the process.)
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.
Troubleshooting a cold underquilt
| What you felt | Likely cause | Fix |
|---|---|---|
| Cold at the feet | Feet riding over the foot edge, or foot cord too tight | Keep feet below the edge; loosen, then lightly snug the foot cord |
| Cold along one side | Quilt pulled away as you moved onto the diagonal | Snug that end cord until the side tucks back in |
| Cold shoulders | A shoulder over the top edge, or top not pulled up | Stay below the edge; raise the head end around your shoulders |
| Cold all over — but it looks perfect when you climb out | A body part is riding over the edge, opening a gap only when you're in it | Get fully inside the quilt's footprint |
| Cold only when it's breezy | Wind moving under the hammock | Pitch the tarp lower and closer |
| Cold everywhere, always | Suspension too loose (gap) or a secondary clip binding it | Reset to lift the empty hammock; remove any extra clips |
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. It only adds insulation beneath you, so 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 our underquilt installation instructions; 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.