Extending the range of your sleeping bag

[Richard Barish]

I was wondering what your experience was with extending the range of your sleeping bag by wearing a down sweater at night. How much colder can you go with a down sweater like a MontBell Alpine Light, which has 4 ounces of 800 fp down? Manufacturers seem to add about 10 ounces of down in going from a 30 degree bag to a 15 or even 10 degree bag, but that is distributed throughout the entire bag and not concentrated on your trunk. The reason I’m asking is that I am thinking about purchasing a MontBell UL Spiral Down Hugger 3 30 degree bag. The bag is irresistibly light at 19 ounces, but while some reviewers and posters find the 30 degree rating to be accurate, others have found 35 or even 40 degrees is the limit for them with that bag sleeping in base layers. My guess would be that a down sweater would add something in the range of 5 to 8 degrees, but that is purely a guess. What’s your experience?

[Jack H.]

For me, after a few weeks of use (the bag will be less warm, the older it is), adding that down jacket would probably make your bag a true 30 degree.

[Jerry Adams]

I have a MYOG bag good to 40 or 50 F.

When I wear long sleeve shirt, down vest with 5 ounces down, jacket I can go down to maybe 20 F.

[Mike M]

Richard- it really varies w/ the user, some sleep at the very warm end of the scale, others the opposite- hence the discrepancy over what temp the bag is comfortable at

clearly the addition of clothing will stretch the limits of your bag (and especially a warm down sweater)- how much is going to be very dependent on where you fall on that scale, I sleep pretty warm and a light down jacket ( w/ a balaclava, mid weigh fleece pants and socks) can gain me another ~ 10 degrees

also what pad you have under you has a pretty profound influence on sleeping comfort- that needs to be taken into account as well

[Richard Barish]

Mike, Jerry, Jack – Thanks for your responses. That gives me some more information about what I might expect.

[Joe L]

+1 to using a winter or double summer pads for lower temps.

Extra clothing is much heavier than carrying a little more down in a warmer sleeping bag. I dress for the daytime/camp temps, expecting to wear all those clothes except for the rain shell in the bag at night. Choose a bag that will accept your bulky winter clothing.

Test your new system outdoors before you try it on the trail.

There is a saying about luck happening to a well prepared mind. That excludes me but it is a good idea to test sleep gear outdoors before walking eight hours away from a trailhead.

[Eric Blumensaadt]

"A man's gotta know his limitations." sez Clint Eastwood. That means, as mentioned above, prior testing of gear before a trip.

My 30 F. WM Megalite bag has, by design, a larger girth than say, the WM Summerlite. As a result I could wear my Thermolite jacket and trousers in it and was comfortable down into the low teens. But I tested it at home the year before.

[Richard Barish]

@ Mike and Hey You: I will definitely get a pad with an R value appropriate to my planned uses. I slept many a good sleep on my old Thermarest years ago, but I’m looking for something lighter now. I like the looks of the Kookabay with synthetic fill (R 5), but don’t know if I want to spend that much on a pad, considering that I’m investing in all new gear and clothes this year. I haven’t really thought that one through yet.

@ Hey You and Eric: My thought was that I would take extra clothes on some weekend trips starting this spring until I got a better feel for how my system performed. An extra pound or two would not be a problem on that kind of trip. I do not want to get caught cold, but I have backpacked a lot years ago and never had that problem; with care, I think I will be able to avoid it again. However, maybe you’re right that at least one night in the backyard is in order. According to Will in his review, the MontBell has “plenty of room inside to wear extra clothing to extend the bag’s warmth,” and I am a small and very skinny guy (125 lbs), so I should be okay on that score if that is, in fact, the bag I end up buying.

Thanks again for the feedback.

[Logan Spader]

Richard, I just purchased the same bag as you. I bought it for a May SHT thru hike where the extreme lows could reach 20 degrees but the average temperatures will usually dip no lower than 40 degrees. I wanted to test my bag to see if I could make it through a night in 20 degree weather.

My gear: non insulated air pad, 7/8 inch 1/2 length ccf pad, Montbell UL SS DH #3, light weight synthetic baselayer

My results: (27 degrees) I froze my butt off. This bag does not have baffles, just a small flap covering the zipper. The 20mph winds shot up through my tent and right into the zipper. Any part of my body touching the zipper was frozen. I could have survived the night but I went inside and snuggled with my lady instead.

I'm keeping an eye on the forecast and the next 20 degree night I have I will be testing it with a puffy jacket and let you know the results.

[Jerry Adams]

It's supposed to be 18 F the next couple nights here

Maybe I'll test something overnight outside on the patio

[V k]

Bag comfort range varies with the user. I've slept comfortably in a summerlight down to 27F with just a mid-weight base-layer top. A down jacket will add to the rating, but it will not be much. I would not expect to lower the bags rating by more than 5F with just a jacket. You will need something for your feet and head as well. A bivy adds just as much if not more and it will stop the wind.

[Richard Barish]

Logan – That is really helpful information. I was concerned about that zipper after reading Will’s description of it in his review, and the conditions you experienced were exactly what I was concerned about. Please do report back on your trial with the puffy jacket. I will be very interested to hear if that works or not for weather in the 20s. I haven’t bought the bag yet, and any additional information you can provide would be very helpful to me in making a decision on it.

Vladamir – Thanks for that feedback. I would expect to be wearing fleece bottoms, socks and a fleece beanie in addition to a down sweater, but if I have to be purchase and carry more substantial bottoms to be comfortable in the 20s with this bag, I might be better off just buying a bag that is a bit warmer.

[Hikin’ Jim]

I'm a cold sleeper. In about 27F weather, I've slept very comfortably in my 32F rated Summerlite when wearing a down hoodie sweater. My legs were slightly cold in just a set of cap 3's, but my head/trunk were stylin'. The down filled hood on my down sweater is really wonderful when combined with the hood of my Summerlite. Totally cozy.

I've now bought a pair of WM Flash down pants. Looking forward to trying those in my Summerlite and seeing how low I can go.

HJ

[Tim Zen]

Jim — let us know how the flash pants work. I have the same bag and similar upper body insulation. At 30F the Ice Breaker bottom was not cutting it.

[Richard Barish]

Jim – That was a helpful comment. I tend to discount legs as a source of cold and discomfort, but that probably is not wise. These comments are making me think that I may should take a hard look at my bag options before I make a final decision.

[Ultralite Hiker]

I have the UL SS DH #3. This past weekend temps got to 28, I froze with REI midweight long underwear, cap 3 top, and an Alpine light, balaclava, and gloves. The next night it was 40 and I was toasty in the same setup. So I would think down jacket would make this around a 33ish degree bag.

[Richard Barish]

Rob – Yikes! 33 WITH a down sweater. That's not so great. But good to know that it is possible that I will respond the same.

[Hikin’ Jim]

Yeah, I've spent some rough nights with cold feet and legs. Fortunately that night that I was referring to wasn't super cold (mid to upper 20's F) — and I had my Patagonia hooded down sweater. With just a base layer I think I would have really sucked it up.

I'll try to get out this weekend to test the new WM Flash pants, if the wx cooperates and the highway guys clear the roads. The Flash pants look like they'll work really well just based on wearing them around the house.

HJ

[Jerry Adams]

I sometimes get cold legs.

If I put on calf high booties it helps a lot.

[Ultralite Hiker]

"Rob – Yikes! 33 WITH a down sweater. That's not so great. But good to know that it is possible that I will respond the same."

I would not say I am an exceptionally warm or cold sleeper. Probably about average. The other guy I was with has the same bag and he froze as well. He had about the same setup except a windshirt instead of the down. He also froze (even moreso than me), although he was in a hammock and I was in the DR.

I love the bag, and it is great to 40 degrees, but I need something warmer for next winter. I am looking at possibly an Alpinlite.

[Logan Spader]

My test was very flawed so don't use it to judge the bag's abilities.

For starters, I set my tent up on our balcony which is three stories in the air. This means that my floorless tent was useless against the 40mph winds because they came up through the balcony floor. Another flaw is that I was using this bag with a noninsulated pad (aside from the CCF under my core). Usually anyone who is planning on camping in below freezing temperatures will have a pad with a higher R value than 1.7. And yet with all of these conditions working against the bag, when I was sleeping on my side my upper shoulder was toasty but my lower shoulder was cold. As soon as the weather warms back up to 20 degrees I will be out testing it again.

[Andrew F]

I would say my experience is about the same as Rob's. (In fact, it's nice to hear some people talking about their "30 degree" bags being closer to 40F, as that's been my experience and most people talk about how they can sleep down in the 20's in their MB/WM 32F bags.)

I have a WM Summerlite, and my general experience has been that I am fine in a fleece layer (capilene 4 long underwear and R1 hoody) down to about 40F. Adding my Montbell UL Down Parka, I have comfortably gone down to 35F. Below 35F, my core and underside are warm, but my legs start to get cold. This is using a full-length NeoAir. I would say my R1+UL Down Parka are probably roughly equivalent in clo value to your MB Alpine Light with a good hat, so you could expect to be comfortable down to about 35F as well.

This is how I planned it, and this system saves me ~10 oz versus carrying a 20F bag. I always bring along an altimeter with built in thermometer, and I'd say historically on 95% of my trips the nighttime low hasn't gone below 35. For the shoulder seasons and higher elevations in the Sierras, I use a 20F bag with 4 more ounces of down fill, but most of the time I enjoy the weight savings of the 32F bag.

Andrew

[Ultralite Hiker]

"I would say my R1+UL Down Parka are probably roughly equivalent in clo value to your MB Alpine Light with a good hat, so you could expect to be comfortable down to about 35F as well."

That is about right. I was pretty warm at 40, freezing at 28. It is a safe assumption that 35 would be comfortable in my setup. As an average sleeper, I categorize this as a 33-35 degree bag with the right sleep setup.

[Hikin’ Jim]

I've found that the way I configure my overall sleep system makes a big difference. In a bivy sack with a 3/4 length pad with only mid weight socks on, I spent a very cold night one September with lows in the upper 30's; my cold feet kept me from getting a good night's sleep. I spent another night in a hammock in the 50's and FROOZE MY PATUKUS OFF. I only had a thin 3/4 length CCF pad (Ridgerest). The night I spent in the upper 20's where I was pretty comfy I had a full length pad and thick socks and my hoodie down sweater.

All in the same Summerlite sleeping bag.

Trial and error seems to have led me to thicker socks at a minimum and a full length pad if it gets down somewhere around 40 or lower. Something like that.

HJ

[Mark Ries]

In my old zoid 1 with a exped synmat 7 last year aug 28 – sept 5 in the wind river range temps upper 20s to low teens my MB spiral down hugger 3 kept me warm with just a synthetic base layer warm socks and hat on the upper 20 nights and I had to add a fleece jacket when the temp dropped in to the lower teens and I was comfortable but I had a warm mat and a tent that blocks wind well there are some benifits from being light weight vs ultra light.And I know I sleep warmer than most. Im trying a light heart solo now and a pro lite xsmall over a 36" closed cell blue ridge pad and my vapor trail under my legs I expect to lose 10deg. more so from the larger (but lighter) tent that wont cut wind quite as well. As you can see Im still a work in progress.

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