Overland Track Nov 2010 - Bivvy enough?

[enduro]

Hi all,

I'm planning on taking a small group through the Overland Track in Late Nov 2010 and having a reasonable idea of the conditions and requirement to "take a tent" I'm wondering if my Outdoor Research Alpine Bivvy (http://www.outdoorresearch.com/site/alpine_bivy.html) and Marmot Hydrogen Down Bag (http://marmot.com/products/hydrogen_reg?p=117,173,74) will be enough. I really don't want to carry a tent.

I understand the temps can be an uncomfortable high in the huts but rather chilly outside!

EDIT By Mod... Don't know what they did to their site, yesterday the sleeping bag link worked and today it's "Page not found"
Here is the new link to the bag - http://marmot.com/products/hydrogen?p=173

[tasadam]

I'm no expert at bivvy's, only time I've seen one being used was when my wife and I wandered down to the helipad at Pine Vally one night and found someone sleeping on it, in a bivvy. The bivvy was white - covered in frost.

But that sleeping bag, not that I know it but it sounds a bit light on to me.

[tasadam]

I should not be looking at gear sites.
An idea,
http://marmot.com/products/helium_membrain?p=117,173,74
Or maybe
http://marmot.com/products/helium?p=117,173,74

[Taurë-rana]

It wouldn't be anywhere near enough for me - the sleeping bag wouldn't be enough even if conditions are not too bad. I've had friends who were caught in some unseasonable but common snow on the OT and they were very scared that they were not going to make it. They weren't inexperienced. November weather is still very changeable, and often miserably cold as well, and that's just in Devonport.
But that's just my opinion, there are others who know the OT better than me.

[ollster]

Going the biv is a nice alternative to tenting. I've carried mine on quite a few trips (Precipitous Bluff, OLT, Mt Thetis Circuit, Western Arthurs, Snowy Ranges and others) but usually only when decent conditions are "expected" (ie: I wouldn't trust the forecast more than 3-4 days out) and not outside the daylight savings "season".

It's a smart idea to carry a tarp, but on the OLT you'll usually be ok to biv on the verandah of the hut. Bear in mind that the possums and other critters will make your nights a bit of a nightmare near the huts. I find my biv nice and warm, so I expect if your sleeping bag is up to it you'll be quite comfortable.

PS: that's a sweet looking bivvy, mine is more of the "body bag" variety.

[Azza]

As Ollster said.. being on many of the same walks as him - I usually only bivvy if the weather is looking good.
Saying that the Overland Track you can always sleep on the verandah, the biggest issue is getting your sleeping bag wet.
I know from experience of bivvying on the Eastern Arthurs and 4 days of rain - nothing was able to stop my sleeping bag from
getting saturation. Probably one of the worst nights I've ever had at Bechervaise Plateau, shivvering in a wet sleeping bag and bivvy
with the rain coming down around me. Wet sleeping bag = clumped down = doesn't work.
Probably didn't help the first night I went to sleep with a crystal clear sky and woke up swimming in my bivvy because I'd slept
with it open.

But as far as the overland goes if it gets too bad you can alway retreat into the hut or at least have some shelter on the
verandah.

Something weird - going on with those sleeping bag links. When I first looked it had a 550gsm sleeping bag rating to -8.
That would be perfect. The 300gsm sleeping is a bit too light for tassie conditions at only -1.1, you'd probably get cold.

[enduro]

There seems to be some consensus that the Marmot Hydrogen (see link in OP) will not be enough.

What do you reckon if I add these to the bag:

Cocoon Silk Liner (+9F): http://www.rei.com/product/735819
Cocoon Thermal Liner: (+12F - not much more than the silk!)http://www.rei.com/product/735819

That would bring the bag down to a potential -12'C. Of course I would be putting thermals on and sleeping in one of my bivy bags or tent - perhaps both.

[alliecat]

Adding two liners will not do much more than adding one. Also, the 9F or 12F benefit claimed for liners like those is just marketing hype. Seriously, if just adding a layer of silk made a 9F difference to the rating of a sleeping bag, the bag manufacturers would sew a silk lining in to every bag. Uninsulated liners keep your bag clean and add a little warmth, maybe a degree or two, but that's all.

The only way to really increase the comfort range of a bag is with more insulation; down or synthetic doesn't matter much, you get more warmth per weight for down, but it's more expensive too. Both Mont and One Planet (to mention two Aussie brands) make sleeping bag "extenders" or "boosters" - the are separate light bags in themselves that will genuinely extend the comfort range of your sleeping bag. The Sea-to-Summit "themolite reactor" liners at REI will work too, but nowhere near as effectively as they claim - you'll notice that they are really just cheap, synthetic sleeping bags so they work the same as a down extender bag. They are heavy for the warmth benefit that you get, but they are cheap at least.

If you already have a puffy jacket, you can stuff that in the bivy inside or outside the bag. If you have insulated trousers, do the same with them. Make sure you have warm, loose socks on, and if the hood of the bag is not really snug, add a hat.

Good luck,
Alliecat

[sthughes]

I reckon in a bivy the Hydrogen bag would be enough, just so long as you have thermals and some dry warm clothes as well just in case you do get a very cold night or two. I have the Marmot Arroyo which is rated the same, just cheaper and heavier. In a bivy (or in my case the slightly more spacious Microlight) I would not think twice about using it on the OT in late spring, unless particularly cold weather was forecast. Of course I always have dry socks, thermals, polarfleece trousers and a down jacket that I can wear to bed if necessary.
Personally I hate the idea of sleeping in a bivy due to the wet weather issues mentioned above, but small windproof bivys and tents do help tremendously with warmth so long as you can keep dry.

[enduro]

Thanks to all for your information and opinions. This type of thread it a good resource for others too.

Thanks for the down sleeping bag extender information AC, it will likely be the direction I head.

Fortunately we will get a very cold spring here in WA and I will get a chance to try the Bivy in the large reserve near my house. In the lower land I'd say it gets close to 0'C on the cold nights.

[Penguin]

I have used a Vaude hooped bivvy, Mont synthetic bag and a thermarest Neo on a couple of hikes now, including a very wet and windy night on Shelf Camp near Mt Anne. I choose a synthetic bag so it did not matter if it got wet from condesation.

Once you are in the bivvy you do not care how bad the weather is outside, you are warm, out of the wind and comfortable. The other two I was with at Shlef camp kept being hit in the face with their tents during the night due to the wind, I slept like a log. I took a tarp but could not get it pegged out because the wind was just too bad. I had previously slept in the bivvy and tarp on my front lawn in wet conditions as a trial and that worked really well. Tarps act like sials in the wind. I was using my walking pole as a centre pole for the tarp.

I now have a S2S hiking umbrella that I am goign to try with the bivvy for cooking and getting in and out of the bivvy in poor weather.

I am not sure I would want the bivvy in really warm weather if there were alot of sand flies/mosquitoes around, you would either boil or be eaten alive.

I would happily use a bivvy when there are huts around as you can cook and socialize in the huts.

The Black Diamond bivvy looks good but is over priced. it was $US150 on a few sites six months ago.

Penguin