The Nest 20°F Hennessy Hammock Underquilt

The Nest is JRB's 20°F underquilt built exclusively for bottom-entry Hennessy Hammocks — and it ships with 25% more down than its box baffles need to hit 20°F, at no extra charge. Box-baffle construction shaped for the Hennessy bottom entry, full suspension and storage bag included, handmade in the USA.

Built for Bottom-Entry Hennessy Hammock Users Who Are Done Waking Up Cold

Sleeping pads don't work in a Hennessy. The pad shifts, the air gap opens, and by 2 a.m. the cold air underneath is winning. The Nest solves this by hanging freely below the hammock shell, keeping the down fully lofted and the insulation where it needs to be — between you and the cold air — all night.

The split entrance with non-snagging mixed hook-and-loop closure attaches directly to the Hennessy's existing entrance hook and loop, retaining full bottom-entry access without modification or hardware. Setup takes under a minute. The Nest is designed for bottom-entry Hennessy Hammocks only — if you have a side-entry or zip-entry Hennessy, the Mt Washington 3 is the right underquilt.

How It's Built: Box Baffles Shaped for the Hennessy Entry

The Nest uses box baffle construction — sealed chambers that hold the down evenly distributed and fully lofted across the full length of the underquilt. The improved foot-end drawcord pulls the underquilt close at the feet to eliminate the dead air pocket that Hennessy users commonly experience under the legs.

Suspension is the JRB Suspension System, included. No sewing, no special hardware, no modification to the hammock. And you cannot be too warm underneath — the same reason you sleep on the same mattress in July as in January. 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. Carrying more rating than the night calls for costs you nothing — here is how to pick between 40°, 20° and 0°F.

Every Nest ships in a storage bag that does not compress the down.

Optimized Fill: 11.01 oz of Down Where 8.8 Would Do

Everyone else calls it overstuff and sells it by the ounce. We call it optimized fill, because a quilt filled only to its base rate fails two ways. The down has slack to move in, so it drifts to one side of a chamber and leaves the other side thin — and a thin chamber is a cold spot. And down loses loft as dirt, body oils and dust work into the plumules, so a quilt with no fill to spare drops below its rating within a season or two.

This quilt's baffles require 8.8 oz of 850FP down to reach 20°F. Every Nest ships with 11.01 oz — 25% over. Not an upgrade, not a dropdown, not priced separately. That extra 2.2 oz is what takes the slack out and supplies the margin — which is why we'll still call this a 20°F quilt in its fifth season.

Why 25% here and 36% on our differential-baffle quilts? Because they are not the same quilt underneath. A box baffle is fully and correctly filled at 25%; the curved, differential-cut chambers in the Mt Washington and Greylock series behave differently under load and need 36% to do the same job. The smaller number is not a smaller effort or a cheaper build — it is the figure this construction calls for. We would rather publish two percentages and tell you why than print one across the catalogue and hope nobody asks.

Here's our arithmetic. Check it against anyone else's.

• 48″ wide, cut to the full length of a bottom-entry Hennessy, box baffles lofting to 2.5″
• That volume at 850 fill power = 8.8 oz base fill rate — the down this quilt needs to reach 20°F
• × 1.25 = 11.01 oz of down actually in the quilt (312.1 g, if you'd rather weigh it)

Those are the numbers to ask any maker for. Matching this much fill elsewhere runs $22 to $33 on top of the listed price, and it is built to order. Ours is in the price and on the shelf. How the base fill rate is worked out, and how to run this comparison on anyone else's quilt.

How the Nest Got Its Name

In May 2004, Jacks R Better introduced the first commercially available underquilt for the Hennessy Hammock. There was no product like it. Hennessy campers had been wrestling with pads and improvised solutions, waking up cold, and making do. The underquilt changed that — hung below the hammock, fully lofted, sealed at the ends, it turned a hammock into a warm, enclosed sleeping system. The name came naturally: you were no longer just hanging in a hammock. You were nested.

The Nest is the product that started Jacks R Better. Everything since — the Mt Washington series, the Greylocks, the camping quilts — grew out of that first Hennessy underquilt. Twenty-two years later we are still the people who make it, and we still put more down in it than the rating asks for.

Handmade in the USA by Jacks R Better, sewn in Pennsylvania — making quilts since 2004. In-stock quilts ship the same or next business day. If it's sold out, order anyway — that puts you in the build queue, and we'll sew yours and ship it in about 2–4 weeks.

For side-entry or zip-entry Hennessy Hammocks, see the Mt Washington 3. For the 0°F version, see the Winter Nest.