Mt Washington 4 0° Winter Hammock Underquilt

The Mt Washington 4 is JRB's 0°F winter hammock underquilt — built for hammock campers who refuse to let temperature set a limit on the season. 850FP down, dual differential cut, JRB Suspension System included.

Built for Winter Hammock Campers Who Won't Let 0°F Call Off a Hang

Sleeping in a hammock compresses every bit of insulation beneath your body flat under your weight — compressed down does not insulate. A sleeping bag used underneath simply cannot solve this problem. An underquilt hangs freely below the hammock shell, never touching you, so the down stays fully lofted and delivers its rated insulation from below. At 0°F there is no margin for a system that underperforms. The Mt Washington 4 was built for those conditions.

How It's Built: Dual Differential Cut, 850 Fill Power Down, 1.1 oz Taffeta Shell

The Mt Washington 4 is built with Dual Differential Contoured Radial Baffles. The inner shell is cut smaller than the outer shell so the quilt conforms naturally to the curved underside of the hammock as it hangs, without the two shells pulling together at the edges and compressing the down. The baffles run radially to follow the contour of your body, keeping loft height constant from head to foot. This is why a differential-cut underquilt runs at its rated temperature when a flat quilt hung beneath a hammock would leave you cold — particularly in winter when there is no margin for cold spots.

The Mt Washington 4 is filled with 850 Fill Power RDS-certified down. Fill power measures how many cubic inches of loft one ounce of down produces when fully expanded — at 850FP, the Mt Washington 4 achieves its 0°F rating with less fill by weight than underquilts built with lower-grade down. Every Mt Washington 4 ships with a 33% overstuff by weight, so it holds its rating even as the down accumulates oils and dirt between cleanings and loses loft.

Suspension is via adjustable shock-cord loops at each end. Cinch the ends tight for a sealed hang on the coldest nights; loosen slightly to vent when the temperature rises. Setup takes under a minute and works on all gathered-end and bridge hammocks — ENO, Hennessy, Warbonnet, Dutchware Chameleon, and most other brands and DIY builds. The suspension system is included.

The shell is 1.1 oz taffeta with a DWR coating on both inner and outer layers. Every Mt Washington 4 ships in a storage bag that does not compress the down — keep the quilt in it between trips for long-term loft preservation.

Named for the Trail

Mount Washington, at 6,288 feet, is the highest peak in the northeastern United States. The summit weather observatory recorded a wind gust of 231 miles per hour in April 1934 — a world record that stood for 62 years. Temperatures drop below freezing every month of the year. The mountain's motto is not a figure of speech: Home of the World's Worst Weather. The Appalachian Trail crosses the Presidential Range just below the summit, exposed above treeline for miles with no shelter from whatever the mountain has in store.

The Mt Washington 4 carries that name because it was built for the same principle: some conditions don't negotiate, and preparation is the only variable you control. This underquilt was built for the nights when you need it to work.

Handmade in Pennsylvania by Jacks R Better — making quilts since 2004. In-stock quilts ship the same or next business day.

Specs: Mt Washington 4 0°F Winter Hammock Underquilt