DIY Nansen choofer clone

Any thoughts anyone?

I’d consider trying a pot with a heat exchanger. I think it is better to reduce the waste heat by using as efficient primary pot as possible, rather than trying to capture the waste heat by other means. The heat transfer is much more efficient when there is a large temperature gradient.

I’m using a HE pot with a solid base, high windscreen (to the rim of the pot) and insulated lid, and it feels like there’s not much usable heat leaving the system. If I stacked another pot on top of that, I guess it can easily loose more heat to the environment than it can extract. The next improvement would be using more reflective base/windscreen. I can hardly imagine anything more complex is worth the effort/money/weight for everything but really long expeditions.

I’ve never seen a pot with heat exchanger big enough to melt snow to hydrate 4 people, perhaps if there is and it saved weight I will consider it. This is for a 30 to 40 day trek so the fuel saved by scavenging every last erg is important. I consider 30 to 40 days a reasonable length of time, we would like to equal Mawsons frugality and equal a gallon of stove fuel every 12 days or approximately 400ml a day but I don’t think any of us are as tough or as fit as Douglas Mawson so we have plans for 500ml a day plus extra

If an annular pot can’t be found or made we may just go with a simple fully enclosed choofer box with shelves

plans for 500ml a day plus extra (for 4 people?)
Mind boggling.
For TWO of us in summer time I allow 30 g / day of canister gas.
For winter time in the snow I allow double that: 60 g/day.
I might push that up to 80 g/day for two if there was no water anywhere. Sue does like a warm breakfast in the snow.

Just how one gets from that to 250 g / day puzzles me. Could be something to do with the serious INefficiency of kero stove use in the field maybe?

Cheers

No Roger it is to do with it being -40C in the Brooks Range in winter

Here I would use 50 to 100mls a day unless melting snow for lots of drinking water/coffee

-20C is easy enough but that next 15-20 degrees makes a lot of difference

If we can’t make the logistics work we’ll do something easier or take a snowmobile tour

Hi Ed

-40 C ALL the time? I was under the impression that -40 C would be the serious lower limit to what might be expected – but I might be wrong. Could you be over-catering? (I don’t know.)

Here I would use 50 to 100mls a day
That is many times what I use. Are you talking about Shellite/white gas? We know from experience that white gas stoves are in practice in the field far more inefficient.

I am going to disagree with you about the difference between -20 C and -40 C in water temperature. The specific heat of ice is about double that of water, which is significant but not earth-shattering. So heating ice to 0 C will take a bit more energy, but melting it will take as much energy as heating water from 0 C to 100 C. That is, the actual melting is what takes the most energy (unless you really want boiling water).

Cheers

Cheers

I may be misunderstanding what people have been telling me but the Nansen design is all about shielding from the wind and extracting as much energy from the fuel as possible by making the hot air path as long as possible. Yes naturally we want boiling water as the freeze dried meals taste bad enough with out having to eat them cold but even if cooking in the tents vestibule the cold air is going to be cold air

-40C is a nominal planning temperature, it could well get a lot colder, it may well be a little warmer but if the locals tell me to plan for -40C then I’m planning for -40C Yep Shellite and 3 brews and 2 hot meals a day here in winter when touring.

A mate who has attempted what we plan to do said we were not be overly cautious although he and his partner used doubled XGK-EXs to cope with the extreme cold and used even more fuel than we are planning on

doubled XGK-EXs to cope with the extreme cold and used even more fuel than we are planning on
The XGKs are not known for great economy. Well, if you are using pulks it may not matter.

Cheers

I would love to find out more about this type of pot!  Even better a lighter version of it! It may be just as good as using a caldera cone type of wind breaker but it  makes sense to keep the unit (Stove, gas, plate) as one unit when space is not an issue (sled use). It saves time and keeps digits warmer.

Hum … could a UL Nansen cooker be the next magic goal?
Gentlemen – start your engines.

Cheers

In his book “Winter Wise” Monty Alford has an illustration of a home made double walled pot. Skirted pots to conserve heat and make boiling faster and more efficient have been around for a very long time, I believe the first iteration was during the Crimea War invented and developed by Alexis Soyer and the Soyer stove was still being used by the Australian Army in the 1970s

Soyer Stove:
https://backpackinglight.com/forums/topic/soyers-magic-stove/

Cheers

Not the same The Soyer stove was a wood fired jacket boiler Roger, a very different beast to his Magic portable alcohol burner

https://calculating.wordpress.com/2012/09/21/forgotten-history-soyers-stoves/

Oh, I know that. He was a fellow stovey: more than one invention.

Cheers

Taking note of your posts on windshields Roger there would be an arguement in favour of a full depth skirt on such a pot if not using a direct clone of the Nansen stove I’m wondering how you would go about adding a skirt to a large pot.

I am thinking of Titanium foil, a series of spacers made from LW tubing and waterproof rivets but I could just use an empty paint tin with exhaust holes added at the top of the skirt

Hi Ed

I think I need a bit of sketch here before commenting.

If I have understood, which is debatable, then such an arrangement sounds a bit clumsy and unpackable. Of course, I keep thinking in terms of a pack rather than a pulk.

Help?
Cheers

Best I can do is an expired eBay link Roger.

Good pictures of the full vented skirt tho

https://www.ebay.com.au/itm/Vintage-Olicamp-Hurricane-Cooker-Stainless-Pot-Camping-Backpacking-Made-In-USA-/232703223045?rmvSB=true&nma=true&si=lJ45btcAfD7AgygtQZ3epsv7u1g%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

Or this link to Amazon courtesy of Zelph

Didn’t know you were here on BPL Moondog :-)

Yep Here too.

Picking all the brains I can before my big trip

Any idea what that skirted pot weighs? That information wasn’t in the add.

7 litres is about right tho for a snow melting pot for 4 persons and most of the other cooking gear should pack inside it

Hi Ed

Ah so. I note in passing that ‘ultra-light’ is the latest marketing buzz-word. It even gets applied to copper-bottomed stainless steel pots. Fancy that!

Well, if I understand the diagrams correctly, then the vented skirt could be useful. However, I doubt that there would be all that much difference in performance between the Olicamp unit and a stock Ti pot with a good windshield around it.

Perhaps the biggest difference would be in weight. A light Ti foil or Al foil windshield is going to be a lot lighter than a rigid outer ‘tube’.

A caution to remember: if you choke the stove by having the windshield too close at the sides, you may seriously increase the CO levels. I tend to err slightly on the ‘lots of ventilation’ side as we always cook inside the vestibule.

Hum – I have thought about this but never done it. If you could find a very light pot which would sit on top of your cooking pot in the same way a lid might (ie clipped in), and you had a very high windshield coming up to near the top of the upper pot, that might make a very effective and light snow melting system.

Cheers

EDIT: ah yes, the 7 L Stove Tec unit. I would not want to carry it for the two of us, but for 4 people with pulks … a thought.

The pieces I’m putting together for you would have the skirted pot as your cooking pot.

I’ll see if I can find the weight for you.

You’re in good hands here with Roger being a fellow Aussie 

Good video of the pot:

I’ve seen such a “skirted” pot made from a double-walled pot sold for heating milk (the space between the walls is filled with water to prevent burning the milk). These pots used to be available in plain aluminium, reasonably light and easy to hack. It used to be a popular DIY item among the winter campers.

Here’s a translation of an old article describing it: http://translate.google.com/translate?js=n&sl=auto&tl=en&u=https://www.svetoutdooru.cz/svet-outdooru/dvojity-hrnec-jak-lepe-varit-v-zimnim-outdooru!/

Now, they sell only stainless steel ones, and the largest I found was 3 liters.