sleeping bag sizes

Andy said:

does anyone no how much having the wrong size sleeping bag effects the temperature rating, as I
own a large size vango bag which has a temperature rating of -20c which is to large for me and
whenever the temperature gets down to around 5c I have to wear thermals when using it. do you
think it could be because of the size?.

It will have *some* effect, as dead space will allow convection currents to set up rather than still
air (which is what does the insulating, the hollow fibre or down just keeps the air still). But not
*that* much effect (25C!), as dead space in an overlarge bag tends to just lie flat.

More likely you either sleep cold and/or the bag is a synthetic past its prime (synthetic bags
degrade very sharply after a few years) or a down bag well overdue for a wash.

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email hidden]
dundee.ac.uk~pjclinchOpen ↗

Peter Clinch said:

Andy said:

does anyone no how much having the wrong size sleeping bag effects the temperature rating, as I
own a large size vango bag which has a temperature rating of -20c which is to large for me and
whenever the temperature gets down to around 5c I have to wear thermals when using it. do you
think it could be because of the size?.

It will have *some* effect, as dead space will allow convection currents to set up rather than
still air (which is what does the insulating, the hollow fibre or down just keeps the air still).
But not *that* much effect (25C!), as dead space in an overlarge bag tends to just lie flat.

More likely you either sleep cold and/or the bag is a synthetic past its prime (synthetic bags
degrade very sharply after a few years) or a down bag well overdue for a wash.

You are doing up the collar and hood to stop the heat falling out? It can be a bit claustrophobic
feeling all tied in but it makes a hell of a difference.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

Peter Clinch said:

Andy said:

does anyone no how much having the wrong size sleeping bag effects the temperature rating, as I
own a large size vango bag which has a temperature rating of -20c which is to large for me and
whenever the temperature gets down to around 5c I have to wear thermals when using it. do you
think it could be because of the size?.

It will have *some* effect, as dead space will allow convection currents to set up rather than
still air (which is what does the insulating, the hollow fibre or down just keeps the air still).
But not *that* much effect (25C!), as dead space in an overlarge bag tends to just lie flat.

And f course the dead space is itself insulated from the air by the bag itself. So unledd the dead
volume is enormous it'll just warm up relatively quickly and absorb no more heat after that.

Quoted message said:

More likely you either sleep cold and/or the bag is a synthetic past its prime (synthetic bags
degrade very sharply after a few years) or a down bag well overdue for a wash.

Or it was misleadingly described in the advertisers' puff.

--
Boo

...and what are you sleeping on? Make sure you have a good thick Karrimat and/or Thermarest under
you (all the way to the feet!) to make sure you keep warm. It's probably the age of the synthetic
bag and the fact that they are never as warm as an 'equally' rated down bag. Try getting yourself a
fleece liner (cheaper to get a fleece blanket from the High Street and sew it up yourself...)
that'll help alot.

Jim www.seasonallyunadjusted.com

The message <[email hidden]>
from Phil Cook <[email hidden]> contains these words:

Quoted message said:

You are doing up the collar and hood to stop the heat falling out? It can be a bit claustrophobic
feeling all tied in but it makes a hell of a difference.

It also makes a hell of a difference having decent insulation under you, particularly with
a down bag.

--
Roger Looking North over the Aire Valley (and Marley Gasworks) to Rombolds Moor Top Posters
killfiled on sight

On Tue, 14 Oct 2003 20:20:27 +0100, Boo <boo@spam_me_no_spam.net>

Quoted message said:

Or it was misleadingly described in the advertisers' puff.

Is Vango a good make of bag? They are going cheap near me.

--
Paul My Lake District walking site (updated 29th September 2003): paulrooney.netfirms.compaulrooney.netfirms.comOpen ↗ 114
Wainwrights

Please sponsor me for the London Marathon at: justgiving.comlondon2004Open ↗

I no when using it, it seems like it is because of there being to much space
to heat, anywhere were there is space becomes very noticeably colder than
the rest of the bag. I thought at first that it might have been advertised
badly but the bag weighs 2.5kg's which is often more than other -20 bags and
the Dupont filling is meant to be good. I have been thinking about maybe
buying a new bag that is lighter and has a temp rating of around -5 but I'm
not shore weather the same thing will happen again. can anyone suggest a
good sleeping bag, that they no goes down to around -5 and is around £100.
cheers
"Boo" <boo@spam_me_no_spam.net> wrote in message
news:[email protected]...

Quoted message said:

Peter Clinch said:

Andy said:

does anyone no how much having the wrong size sleeping bag effects the temperature rating, as I
own a large size vango bag which has a temperature rating of -20c which is to large for me and
whenever the temperature

gets

Quoted message said:

Quoted message said:

Quoted message said:

down to around 5c I have to wear thermals when using it. do you think

it

Quoted message said:

Quoted message said:

Quoted message said:

could be because of the size?.

It will have *some* effect, as dead space will allow convection currents to set up rather
than still air (which is what does the insulating, the hollow fibre or down just keeps the
air still). But not *that* much effect (25C!), as dead space in an overlarge bag tends to
just lie flat.

And f course the dead space is itself insulated from the air by the bag itself. So unledd the dead
volume is enormous it'll just warm up relatively quickly and absorb no more heat after that.

Quoted message said:

More likely you either sleep cold and/or the bag is a synthetic past its prime (synthetic bags
degrade very sharply after a few years) or a down bag well overdue for a wash.

Or it was misleadingly described in the advertisers' puff.

--
Boo

Paul Rooney said:

Is Vango a good make of bag? They are going cheap near me.

Pretty much across Vango's ranges for everything they strike me as competent, fairly priced and good
but not great.

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email hidden]
dundee.ac.uk~pjclinchOpen ↗

Andy said:

badly but the bag weighs 2.5kg's which is often more than other -20 bags and the Dupont filling is
meant to be good.

Dupont make pretty much all the good synthetic insulations, but they all go rather cool after a few
years, so the age of the bag will have a big affect on its warmth if it's synthetic.

Quoted message said:

buying a new bag that is lighter and has a temp rating of around -5

It will only have that sort of rating for about 3 years or so if it's synthetic, and that assumes
you don't sleep cold (no standard for sleeping bag ratings, as people work different ways: I've been
too hot in a knackered old 3 season synthetic used as a quilt in the same room on the same night as
someone was quite happy fully zipped into a -25C expedition down bag. Manufacturers give an educated
guess, but some are more optimistic than others and even with the best will in the world it won't be
right for everyone).

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email hidden]
dundee.ac.uk~pjclinchOpen ↗

On Wed, 15 Oct 2003 04:16:25 +0100, Paul Rooney <[email hidden]>

Quoted message said:

Boo boo@spam_me_no_spam.net said:

Or it was misleadingly described in the advertisers' puff.

Is Vango a good make of bag? They are going cheap near me.

Sounds like they didn't remove all the chickens from the feathers...

On Thu, 16 Oct 2003 00:47:57 +0100, Stuart Baldwin <[email hidden]>

Quoted message said:

Paul Rooney said:

Boo boo@spam_me_no_spam.net said:

Or it was misleadingly described in the advertisers' puff.

Is Vango a good make of bag? They are going cheap near me.

Sounds like they didn't remove all the chickens from the feathers...

Groan!

--
Paul My Lake District walking site (updated 29th September 2003): paulrooney.netfirms.compaulrooney.netfirms.comOpen ↗ 114
Wainwrights

Please sponsor me for the London Marathon at: justgiving.comlondon2004Open ↗