Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Bushwalking gear and paraphernalia. Electronic gadget topics (inc. GPS, PLB, chargers) belong in the 'Techno Babble' sub-forum.
Forum rules
TIP: The online Bushwalk Inventory System can help bushwalkers with a variety of bushwalk planning tasks, including: Manage which items they take bushwalking so that they do not forget anything they might need, plan meals for their walks, and automatically compile food/fuel shopping lists (lists of consumables) required to make and cook the meals for each walk. It is particularly useful for planning for groups who share food or other items, but is also useful for individual walkers.

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Lamont » Sat 17 Feb, 2018 2:37 pm

Might I respectfully say CCF on top of mat, not below for best effect.
Who knows what evil lurks in the hearts of men?
User avatar
Lamont
Phyllocladus aspleniifolius
Phyllocladus aspleniifolius
 
Posts: 767
Joined: Sun 21 Feb, 2016 1:27 pm
ASSOCIATED ORGANISATIONS: Societe' de Lamont Cranston
Region: Victoria

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Moondog55 » Sat 17 Feb, 2018 2:58 pm

Lamont wrote:Might I respectfully say CCF on top of mat, not below for best effect.


I have to say I have experimented with both approaches, CCF on top is warmer initially but underneath it is as warm in the end so I have always used the CCF underneath to protect the expensive blow-up. In very cold weather I might use a 3mm + RFL above as well as underneath. Things changed for mew when it got to -25C when I used both a cheap 8mm CCF and a RidgeRest but that was under my older 3/4 T'Rest

To the OP
Hikingnewbie Keep your eyes open for people renovating and laying engineered flooring, there are usually off-cuts of the underlay being chucked out. This stuff is very usefull for boosting the rating of a mat, but this thin stuff does work better on top, usually 2mm or 3mm foam of some description plus that reflective foil layer. You only need a section across the roll as wide as your mat but if you find a larger piece it is Also very handy under the floor of your tent in place of a factory footprint and as part of a sitamapon
Ve are too soon old und too late schmart
Moondog55
Lagarostrobos franklinii
Lagarostrobos franklinii
 
Posts: 8975
Joined: Thu 03 Dec, 2009 4:15 pm
Location: Norlane Geelong Victoria Australia
Region: Victoria
Gender: Male

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Warin » Sat 17 Feb, 2018 3:44 pm

Lamont wrote:Might I respectfully say CCF on top of mat, not below for best effect.


Why?

Some of my foam mats have a reflective layer, I place the foam mat on the ground with the reflective layer upper most, then the tent floor then the inflatable mat. This provides protection to the inflatable mat. It would be better if there were an air gap around the reflective layer, but failing that I think placing it between the insulation is better than on the outer side, my thinking is this keeps it cleaner and reduces any damage to it.

I don't see how which insulating mat on top significantly changes the overall insulation. The maths of R values looks to confirm that conclusion. Am I missing something?
User avatar
Warin
Phyllocladus aspleniifolius
Phyllocladus aspleniifolius
 
Posts: 723
Joined: Sat 11 Nov, 2017 8:02 am
Region: New South Wales

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Lophophaps » Sat 17 Feb, 2018 4:59 pm

Lamont wrote:Might I respectfully say CCF on top of mat, not below for best effect.

That would smooth out the bumps in the air mat, but I can't see the insulation improving. Someone with better physics knowledge than me will have to work this out. The sequence when setting up camp may be useful to consider.

Tent up, take out a few things from the pack, and then unroll the CCF mat. Sit on this while unpacking, and then blow up the air mat, which goes on top of the CCF mat.

I like the CCF underneath as it give a layer of protection against prickles. That said, my Thermarest lasted for about 20 years until it developed a giant bubble; prickles were not a problem. Apart from snow camping I did not use a CCF mat with the Thermarest.
User avatar
Lophophaps
Auctorita modica
Auctorita modica
 
Posts: 2666
Joined: Wed 09 Nov, 2011 9:45 am
Region: Victoria
Gender: Male

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Lamont » Sat 17 Feb, 2018 6:24 pm

My thoughts are the "thin (you referred to) CCF pad", (3-4 mm I supposed a la GG for example) will more effectively block the cold air in your mat from getting nearer to you and cooling you and restricts the warm air from escaping.
Putting it under may stop the ground temp from affecting the mat directly as much but, it will not stop the air temp in your tent which may be about or even below zero, from cooling the air in the mat and allowing it to transfer to you if the R value (insulation) is too low. I believe it raises the insulation nearest to your body thus allows you to hold the warmth (or repel the cold) better.
Essentially you get two layers of insulation against all the cold (ground/snow-plus air in tent) that could affect your body.
Who knows what evil lurks in the hearts of men?
User avatar
Lamont
Phyllocladus aspleniifolius
Phyllocladus aspleniifolius
 
Posts: 767
Joined: Sun 21 Feb, 2016 1:27 pm
ASSOCIATED ORGANISATIONS: Societe' de Lamont Cranston
Region: Victoria

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Warin » Sat 17 Feb, 2018 6:46 pm

Lamont wrote:My thoughts are the "thin (you referred to) CCF pad", (3-4 mm I supposed a la GG for example) will more effectively block the cold air in your mat from getting nearer to you and cooling you and restricts the warm air from escaping.


That assumes that air circulates inside the inflatable mat. If that were so the inflatable mat would have a very low R value.

Lamont wrote:Putting it under may stop the ground temp from affecting the mat directly as much but, it will not stop the air temp in your tent which may be about or even below zero, from cooling the air in the mat and allowing it to transfer to you if the R value (insulation) is too low. I believe it raises the insulation nearest to your body thus allows you to hold the warmth (or repel the cold) better.


If the air in the inflatable mat circulates then it will also circulate when in the lower position thus it will not be very effective there either. In fact the contact with the ground would lead to more loss as the ground contact will transfer energy at a greater rate than air contact. And the contact area with air inside the tent (when used in the upper position) is much smaller than the contact area with the ground (when used in the lower position). Think you will find it best even with a inflatable mat that has lots of air circulation (e.g. the old lie low) on top of the foam mat.

[edit] - Still thinking on it [/edit]
Last edited by Warin on Sat 17 Feb, 2018 7:08 pm, edited 1 time in total.
User avatar
Warin
Phyllocladus aspleniifolius
Phyllocladus aspleniifolius
 
Posts: 723
Joined: Sat 11 Nov, 2017 8:02 am
Region: New South Wales

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Zapruda » Sat 17 Feb, 2018 7:02 pm

There is plenty of anecdotal evidence around claiming that a mat on top is more effective. I have tried both in the snow and haven’t noticed any difference. I certainly prefer the mat on top for comfort.

Roger C may have some thoughts on the matter.
User avatar
Zapruda
Phyllocladus aspleniifolius
Phyllocladus aspleniifolius
 
Posts: 876
Joined: Thu 07 Apr, 2016 10:46 am
Region: Australian Capital Territory
Gender: Male

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby slparker » Sun 18 Feb, 2018 8:19 am

This was discussed at some length on the American forum 'backpacking light'.
The consensus, anecdotally, was that ccf mat on top was warmer but I find the physics very unconvincing.
Except a good point was made that point compression (I.e. elbow, hip) lowers R value ( resistance to conductivity) considerably and adding a stiffer layer on top reduces this.
https://backpackinglight.com/forums/topic/56634/

They did testing, and field testing, of several mats In their technical mat test ( behind a paywall) and they describe a 'foam overlay' as being an effective booster but do not describe why an overlay is better than an underlay; or, so far as I can discern, did not test the combo or explain the physics.
The test was co-authored by Roger Caffin, a regular contributor to this forum, so he might weigh in.
slparker
Athrotaxis selaginoides
Athrotaxis selaginoides
 
Posts: 1149
Joined: Fri 25 Apr, 2008 10:59 pm

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Moondog55 » Sun 18 Feb, 2018 10:04 am

My understanding is that with the CCF layer on top you are not wasting any energy heating up the air in the blow-up mat and the colder it is the bigger that cold air sink is going to be. However I think it differs for each mat and each mat combination.
I do notice a small chill when using my old Thermarest mats and that takes a few minutes to dissipate, in other words it takes a few minutes for the air and foams temperature to come up to my own body temperature, this is much less noticeable with my S2S Comfort Plus
There being such big differences between mats and between mat combinations that each has to be taken as an individual case I think
I have some RFL coated Urethane mat here if somebody wants to come and collect to do their own experimentation with this while season
Ve are too soon old und too late schmart
Moondog55
Lagarostrobos franklinii
Lagarostrobos franklinii
 
Posts: 8975
Joined: Thu 03 Dec, 2009 4:15 pm
Location: Norlane Geelong Victoria Australia
Region: Victoria
Gender: Male

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby Lamont » Sun 18 Feb, 2018 10:31 am

Yes, I believe I may have read about it on BPL.
Until we find out more I propose all interested parties head out to the Ponds Institute- sleep 3 nights mat on top, 3 nights mat on bottom.
Identical internal/external conditions for all participants.
Independently randomised groups.
The hypothesis is: Sleeping with a CCF mat of 3mm on top of a Xlite will be warmer than with the CCF on the bottom.
Methodology: Each participant will be woken every 2 hours to record their comfort level as determined by the (choose name) Comfort Scale.
Fully catered with massages after each days walking and a couple of Daquiries/Whiskey before bed.
I would love to do this! Not sure if the Ponds Institute will allow it though.
Who knows what evil lurks in the hearts of men?
User avatar
Lamont
Phyllocladus aspleniifolius
Phyllocladus aspleniifolius
 
Posts: 767
Joined: Sun 21 Feb, 2016 1:27 pm
ASSOCIATED ORGANISATIONS: Societe' de Lamont Cranston
Region: Victoria

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby CBee » Sat 22 Dec, 2018 7:22 am

I own a standard thermolite reactor and an extreme one. I also use them as standalone mid season in QLD. Paired with my down bag and insulated mat, in NZ below zero, I never had a problem being cold at night. I haven't tried different brands but I'm quite happy with them. Not sure about the claimed temperature gain: one night I was sleeping in a hut and I was little cold. I decided to use the thermolite and made a significant difference. I think it is important to seal them properly to stop cold air going inside the bag.
I also noticed I posted this on the wrong thread. Sorry.
CBee
Atherosperma moschatum
Atherosperma moschatum
 
Posts: 62
Joined: Fri 21 Dec, 2018 7:18 am
Region: Queensland

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby wayno » Sat 22 Dec, 2018 3:58 pm

its overkill for the milford, all the huts are at low level... you'll sweat.... somewhere around ten degrees is plenty. take some extra clothes if the forecast is bad
from the land of the long white clouds...

NZ Tramping News https://www.facebook.com/groups/208124842637462/
User avatar
wayno
Lagarostrobos franklinii
Lagarostrobos franklinii
 
Posts: 8443
Joined: Sun 19 Jun, 2011 7:26 am
Location: NZ
ASSOCIATED ORGANISATIONS: Sportzhub.com contributor;
Region: New Zealand
Gender: Male

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby ribuck » Sat 22 Dec, 2018 7:05 pm

Warin wrote:I try to keep the grams to $ ratio at at least 1 gram to 1$ ... less than that and I think I'm better off spending it on the holiday.

Yay! On that basis I can justify a DCF tent! And to think I've been putting it off all these years.
User avatar
ribuck
Athrotaxis selaginoides
Athrotaxis selaginoides
 
Posts: 1138
Joined: Wed 15 May, 2013 3:47 am
Region: Other Country
Gender: Male

Re: Down Sleeping Bag - Is Comfort Rating of 0 deg C enough?

Postby gbagua » Wed 26 Dec, 2018 9:58 pm

Mont is a premium Australian manufacturer of sleeping bags. I can vouch for their products. A1.

https://www.mont.com.au/sleeping-bags

Sure you can find something there that suits your current needs.
User avatar
gbagua
Athrotaxis cupressoides
Athrotaxis cupressoides
 
Posts: 270
Joined: Sat 20 Oct, 2012 9:04 pm
Region: Queensland

Previous

Return to Equipment

Who is online

Users browsing this forum: Google Adsense [Bot] and 4 guests