Mt Washington 4 0°F Winter Hammock Underquilt
$359.95
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![Eric Hansen review photo]()
Mt Washington 4 0°F Winter Hammock Underquilt
$359.95
15.52 oz of 850FP down where 11.4 hits the 0°F rating — 36% optimized fill, standard. It doesn't add loft; it stops the down shifting and holds the rating for years. Dual differential cut, suspension included.
🔥 Only 1 left — ready to ship - same or next business day
The Mt Washington 4 is JRB's 0°F winter hammock underquilt — full length, and filled 36% over what its chambers need to hit 0°F, at no extra charge. Dual Differential Contoured Radial Baffles — the construction we invented — plus the JRB Suspension System and a storage bag, handmade in the USA.
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 — and compressed down does not insulate. A sleeping bag used underneath cannot solve that. 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, and that is the whole reason this quilt is built the way it is.
At 77 inches it covers you head to foot — no sit pad, no pack panel, nothing to arrange around your legs before you can sleep.
How It's Built: Dual Differential Cut — The Construction We Invented
The Mt Washington 4 is built with Dual Differential Contoured Radial Baffles — a construction we invented at Jacks R Better and have been sewing underquilts with since 2004. It is the thing that separates a purpose-built underquilt from a top quilt repurposed underneath. The inner shell is cut smaller than the outer shell, so the quilt conforms to the curved underside of a loaded hammock instead of the two shells pulling together at the edges and compressing the down between them. The baffles run radially to follow the contour of your body, which is what holds loft height constant from head to foot as the hammock changes shape under you.
Suspension is by adjustable shock-cord loops at each end, included — and you cannot hang it too tight. Because the outer shell is cut larger, it keeps its slack no matter how far you pull the suspension down, so tightening seals the edges against draughts instead of crushing the loft. Ease those same cords off instead and the quilt eases away from the hammock, letting air move across your back — we call it opening the windows, and it is handy on the nights you climb in hot. You also 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. Setup takes under a minute on all gathered-end and bridge hammocks — ENO, Hennessy, Warbonnet, Dutchware Chameleon, and most DIY builds.
Every Mt Washington 4 ships in a storage bag that does not compress the down.
Optimized Fill: 15.52 oz of Down Where 11.4 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 chambers require 11.4 oz of 850FP down to reach 0°F. Every Mt Washington 4 ships with 15.52 oz — 36% over. Not an upgrade, not a dropdown, not priced separately. That extra 4.1 oz is what takes the slack out and supplies the margin — which is why we'll still call this a 0°F quilt in its fifth winter. At 0°F that margin matters more than on any other quilt we build, because a quilt that has quietly drifted to a 10°F reality is a problem you discover at two in the morning.
Here's our arithmetic. Check it against anyone else's.
- 42″ × 77″, 11 chambers × 3″ baffle walls, lofting to 3.5″ = 9,702 cu in internal volume
- 9,702 ÷ 850 fill power = 11.4 oz base fill rate — the down this quilt needs to reach 0°F
- × 1.36 = 15.52 oz of down actually in the quilt (440.1 g, if you'd rather weigh it)
Those are the three numbers to ask any maker for. Matching this much fill elsewhere runs $41 to $62 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.
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 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. Finished quilts go to the people already in line, so waiting for one to reappear on the shelf usually means waiting longer.
Specs
| Weight | 24.59 oz (0.7 kg) |
|---|---|
| Length | 77.0 in (1.96 m) |
| Width | 42.0 in (1.07 m) |
| Temperature rating | 0°F (-18°C) |
| Down fill power | 850+ |
| Down weight | 15.52 oz |
| Loft | 3.5 in |
| Shell | 1.1 oz Taffeta w/ DWR |
| Construction | Dual Differential Contoured Radial Baffles |
| Features | Underquilt – Winter |
| Includes | Zippered storage bag, JRB Suspension System |
| Made in | Hulmeville, Pennsylvania, USA |
E
Bought this along with a 20deg top quilt. Shipped out to me quickly and are both very well made. Looking forward to many a backpacking trip with these!
J
100% top quality
K
My JRB quilts have kept me warm on three camping trips now. I was cozy through several nights of sub-freezing temps and lots of wind. They are more than just functional; they’re downright luxurious. Love them and look forward to many more nights with them.
R
Simply put, this is one terrific underquilt. I'm a cross-country bicyclist that's been traveling the country for The last 5 years. And have been constantly been updating and modifying my sleep system.
The first night out it kept me nice and toasty warm I warmed up evenly and quickly, and the ease of installation was really nice. I didn't have to fiddle around making a bunch of adjustments, and more importantly it kept me warm.
As a cross-country bicyclist slash nomadic bicyclist I am always looking to lighten my load and make my packing of my home and unpacking of my home easier. This new quilt completely removed a synthetic 20 degree quilt in ways absolutely nothing and stores away easily.
Thanks Jack's r better
Raven
s
This quilt has full more than full coverage for a 6' human, is incredibly warm and is very well built! Thanks JRB!
L
Used my Mt. Washington 4 twice this past week. On the first outing it snowed and temps dipped to 3.9F. On that night I did not stack under quilts, and the Mt. Washington was very warm in a Chameleon. On New Years Eve, i stacked the Mt. Washington with another UQ (ENO Blaze) in order to break the wind and provide some protection to the Mt. Washington. Temperatures lowered to -16F with a breeze blowing at a steady 10-15 mph. The combination of two UQ completely blocked the cold on my underside.
I have used the Mt. Washington on 10 or 11 outings since I got it, and I have been very, very pleased with its performance. I would highly recommend this UQ to anyone with low temperature needs.
&
just finished 3 ridges wildernss temps were in the 20's at night .. the mt washington 4 and hennessy expidetion drew alot of attention at the shelters and i could feel some of the envy. quilt was extreamly warm and im 100% sure i had the best night sleep out of everyone out there. only problem i had with it was i didnt want to get out of it.. i orderd and picked up in store it was really cool to see all the gear in person outatanding products and service ... at 5'5 i can use it as a blanket and i plan to on family tent trips. .
J
This review is long overdue. I heard about JRB from a friend and after agreeing to go winter camping, I decided to start looking into one. After speaking with Jack Tier a few times, I decided to go with the MW4 with 2oz overstuff and the active dry. I ran this UQ with a HH Deep Jungle XL on a winter advisory weekend in the Seneca Rocks National Recreational Area. It quickly dropped into the single digits after our arrival, and probably below zero with wind chill. Living most of my life in the south, I was not used to this kind of cold. Every liquid not on the fire ring froze in minutes. BUT I slept VERY warm and even had to vent out some heat at times. The UQ was very warm and its design fit my hammock perfectly with very easy setup even with gloves on. I cannot give enough praise of the MW4 and I look forward to trying other JRB products in the furure!
B
This review is quite late, as I got the MW4 UQ several years ago. I had given it an extensive review over at one of the hammock forums, but I did not remember to also review it here. So I will do so now.
This was my first UQ, one of their very first models with untreated down.
A summary of cold weather use:
1:Placed on the War Bonnet Black Bird hammock. This proved to be far more involved than using it on the JRB bridge hammock. Still, following the directions, and making a few tweaks here and there, it was accomplished, or at least appeared to be so. Now this night was no real test for the quilts temperature rating, it only got down to 18°F. However, it was very windy, and since I was in the backyard I could not really seek out a sheltered location. And those high winds did seem to shift around quite a bit during the night, coming from different directions. So sometimes my large tarp did a good job of blocking the wind. other times, I think maybe it did not. Sometimes my hammock was swaying in the wind, either from the wind hitting the hammock or the stand, don’t know. But either way, my back, butt and legs were toasty warm all night. So I'll have to call that one a total success, below 20F/high winds.
2: Next( and all following) test was on a JRB BMBH(bridge hammock). I had left the hammock and quilts out all night, and the temperature dropped to 27F. I did not sleep out that night, but I woke up a bit before 5 AM and decided to go out and give it a try. I found my tarp, top quilt and under quilt all covered in a thick layer of frost. So I replaced top quilt with a dry one from in the house, but left the under quilt as it was, and crawled in. I stayed there for a few hours, and though it took me a bit longer than usual to warm up(not surprisingly considering the frost covered under quilt that was probably the same temperature as the air), before too long I was once again nice and warm.
3: Next test was on a February, very rainy (turning to about 5 inches of snow), backpack/ group hang in the Sipsey wilderness of North Alabama. I believe it dropped once again to about 27°F as the rain turned to snow. I think it might've been around 2 or 3 AM that I had to get up to pee and I realized that I was a little bit on the cool side. My long/wide down top quilt only weighed 21 oz, so it was not good for temperatures much below 30F, that's for sure. Although I did have on some warm clothing, a fleece cap covered with the hood of my thin(12 oz size extra large) synthetic jacket. But, I had with me a separate down hood. I put it on and crawled back in, and quickly warmed up and was toasty warm the rest of the night. Another total success as far is this under quilt went.
4: Finally, my only real test anywhere near the quilts temperature rating, though I still did not manage to get down to zero. By the time I crawled in about 11PM, the quilts and tarp were once again covered with frost! Not exactly a fair way to start a test. We made it down to about 11F. I wore my usual warm clothing. I had some top warmth issues through the night, and the TQ got soaked with condensation in the layer near my neck/chin. At some point I replaced the TQ with an old synthetic bag rated for 5F, used as a TQ when on my side, but I got in the bag when on my back so the hood would not be in my face, and had luxurious warmth after that, either way. My back was nice and warm the entire night.
So there you go, this UQ has always kept me warm near or above the rated temps. And it does not weigh much and compresses quite nicely. It would be hard to beat this quilts performance IMO.
T
To me customer service is every thing, that being said Jack was so supportive with all my questions, I have a Lawson blue ridge hammock and the quilt with Jacks help works great. If your looking a under quilt look no further, this quilt is high quality and very very warm.
S
Just got my Washington 4. Researched a lot of quilts and finally pulled the trigger on this quilt. Great customer service and the quilt is toasty warm and very light. Highly recommend. Thanks Jack.
T
I bought this underquilt for my App Trail thru hike in 2015. The 4th night I was out (March 3rd or 4th) it began raining ice and blowing snow. In a matter of an hour it went from a pleasant hike on the mountain to a dangerous ice blizzard. After what seemed like forever I got my hammock up (being the wind was blowing like mad and my fingers were numb it took a bit). Once the hammock was up I easily put the underquilt on and crawled into my hammock. I was cold and somewhat terrified as my hammock was swinging from side to side with the intense gusts of wind. This underquilt kept me from getting severe exposure. The wind did cause some cold spots which made me need to reposition myself every few minutes, but otherwise I was warm.
I used the quilt for another 2 months and every night I was warm and comfortable even in lousy weather. As the weather got warmer I sent the quilt home (its a bit bulky and I was going ultralight (12-15lb pack) at that point). I went thru 4 lightweight sleeping pads (to fight off cold butt syndrome), trying each one out and sending it home. I ended up settling for an exped synmat. None of them were as warm and comfortable as this underquilt. This year Im just gonna order a lighterweight quilt and ditch the pads. You just cant beat them.
R
Broke out the hammock gear last night. Temp was 30 deg. The mt Washington under quilt kept me warm all night. Thanks for a good nights sleep. Great product
A
New to hammock camping. I did extensive research and ended up choosing this product. I took my under quilt out of the packaging 10 minutes before setting up camp at midnight. I promptly installed the under quilt incorrectly. The gusty 20 degree mountain air gave me a bit of a cold back and butt. Night number two brought the same conditions, and this time I took time to install the under quilt correct.... best/warmest sleep I have ever had outdoors. Period. Excellent product. Great customer service. Fast shipping. Made in the USA. Can't wait to do some deep winter camping with this.
C
Backpack Gear Test of the Mt Washington Quilt
R
Backpack Gear Test of the Mt Washington Quilt
T
Backpack Gear Test of the Mt Washington Quilt