Thermarest Haven -6°C (20°F) Sleeping Bag?

[royAB]

Anyone have/used one of these? (http://tinyurl.com/d5gsu7c)

Would welcome comments if so.

Am tempted because;

The whole 'no zip', differential fill = lighter weight angle seems to make a lot of sense.
I like a hood and none of the more 'popular' quilts I've looked at have one.

I'm hesitant because;

For a bag that weighs just over 600gm with 700 down, the claims of -1deg comfort seem a little optimistic.

(For reference on my personal hot/cold sleep thing, I spent last night - clear sky, no wind - in a PD600/Hunka/Hyalite Peak Elite and temp went to 0deg at about 3am. Put on a light down jacket - to compliment merino top, leggings, socks & beanie - but was not really sleep-comfortable after that)

[Anthony]

If 600g of down at 0'c was cold, 300g ain't going to cut it, certainly not without a well insulated mat that will offset any weight savings and loose its versatility.

[royAB]

Indeed, but then we are talking 'top bags' here so the 300gm is predominantly on the top and definitive makers of 'similar' (using that term in it's loosest sense) bags publish figures that aren't much different eg Nunatak's Catabatic SL: 360gm fill -7deg.

(The weight penalty for the 'well insulated mat' is, for me anyway, a given - around 400gm for my Synmat UL - I like to be comfy

[johnnystorm]

I've got one that I use with a neoair xtherm. I can't tell you exactly what temp I've used it in but it's seen action during Jan, Feb & March used in a Bivi bag. I've generally had my base layers on. To be honest I think I'd rather have a hat on than use the hood. Fitting an xtherm in it makes it too tight. I've just got in on top of the mat and not bothered with the strapping. If you're after a long one all outdoor.co.uk might be a smidge cheaper.

Overall I'd recommend one.

[Anthony]

The problem with relying on the figures alone is that there is no mention on the r-value the mats that the bags tested in conjunction with. In fact, iirc, there is no recognised formal classification for top bags for this very reason.

I'm not knocking the bag, or top bags in general, just that given ur experience it might not be as warm as they claim.

:)

[royAB]

Indeed, in my experience they're never as warm as the labels claim and there's no reliable 'common' stat for bags of any sort (for good reason - http://tinyurl.com/d3swn39). Thankfully there are places like this where real users share real experience... always the best help IMHO

[Anthony]

The EN13537 classification is fairly well accepted, although largely recognized as being misleading, it does help to compare one bag against the next. Top bags and quilts are excluded from the ratings though, as they can't be compared like for like.

We're arguing the same point mind, that real world experience is far better than any 'rating'.

[royAB]

Yup.. same point, same conclusion

[Anthony]

Altho, maybe I've read it wrong somewhere, as the top bag you link does indeed have an EN rating :!:

I suspect your PD has better down, but if you were to remove the 300g of down that's hypothetically on the underside half of the PD and used it with an insulated mat instead, would that make it any warmer?

Just maybe, with more room to loft inside an air bed rather than being squished, the 300g of surplus down would actually be more effective and thus make the 'system' warmer.

But then at best your UL7 would have circa 170g of synthetic fill, and a mat with 300g of down fill is going to be pushing 6-700g if not more.

[royAB]

Cheers Johhnystorm.

Q; Did you use it inside a bivy bag/under tarp? (I know I get a deg+out of adding the bivi and another from a low tarp..)

[johnnystorm]

Jan was in a Tent, Feb in a Bivi Bag on a beach (no shelter), March in mid-snowmageddon was in a Bivi bag again amongst trees. I was also in a silk liner but its paper thin and only used to keep it clean rather than thermal.

[royAB]

Cheers Johnny, most useful