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A desert crossing
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alastair humphreys
(alastairhumphreys) - MLife

Locale: UK
A desert crossing on 09/17/2012 15:27:30 MDT Print View

I am about to walk 1000 miles across a hot desert with a friend and would like any thoughts on essential kit, clever tricks and so forth.

In particular I am interested in:

- designing my own tarp / tent shelter
- footwear: trainers or boots?
- homemade lightweight sand gaiters
- cart design. I am working on this design but am definitely open to improvements. It needs to hold about 300kg of water... (I KNOW that is not LIGHT travel! SORRY guys!) -
- the lightest possible rucksac (for emergency evacuations) that is large enough to hold a 25 litre jerry can
- chest-mounted camera packs

I have posted a couple of things on BPL before and have always been amazed at the knowledge and enthusiasm, so I thank you in advance!

Craig W.
(xnomanx) - F - M
A desert crossing...Carts on 09/17/2012 18:57:49 MDT Print View

I've always been interested in a desert cart for water hauling...Here's the best one I've seen. This is a rickshaw design with modular tires; one MTB set for average terrain, one set of balloon tires for mud and sand. It's even equipped with brakes for the downhill.

(from the Rick Ridgeway, Galen Rowell, Conrad Anker, and Jimmy Chin expedition in Tibet's Chang Tang Plateau).

I've been curious about how well one could be designed with only a single rear tire (think BOB trailer meets rickshaw, but still supported with a waistbelt and handlebars like in the video), though your load would have to maintain a very low center of gravity for it to be stable (if it's even doable with a single tire).

Ken T.
(kthompson) - MLife

Locale: Behind the Redwood Curtain
Re: A desert crossing...Carts on 09/17/2012 19:05:50 MDT Print View

for Craig

Craig W.
(xnomanx) - F - M
Re: Re: A desert crossing...Carts on 09/17/2012 19:13:40 MDT Print View

I knew I saw it somewhere, thanks Ken. I've envisioned something similar, but with a fatter rear tire to float better, a bit more of a basket on the frame for gear, and possibly some handlebars with a brake similar to the rickshaw design.
I could see it working well enough for much of the open desert I know.

Jim Colten
(jcolten) - M

Locale: MN
Re: A desert crossing...Carts on 09/17/2012 21:00:29 MDT Print View

I could see it working well enough for much of the open desert I know.

With a light load .... sure. With 300kg (661 lbs) of liquid, far from sure.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Re: A desert crossing...Carts on 09/17/2012 21:18:43 MDT Print View

Me thinks a cart would limit where you could go. My desert trips often look like this. Most deserts aren't flat and are full of mountain ranges, ridges, canyons and the like.

Fortification Hill view #1

Charles P
(mediauras) - F

Locale: Terra
Re: Re: Re: A desert crossing...Carts on 09/17/2012 21:41:06 MDT Print View

What about a camel instead?

Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
Re: A desert crossing on 09/17/2012 21:54:54 MDT Print View

Hi Alastair,

Depends on what kind of desert. Are you talking mostly sand, or mostly rock.

There have been a number of self propelled trips across the Australian deserts since the sixties when warren Bonython walked the Simpson, including a couple in the last decade.

Cart design will depend on terrain to a certain extent. I've wondered whether a Chinese wheelbarrow design might be feasible.

Regards, Rod

drowning in spam
(leaftye) - F

Locale: SoCal
Re: A desert crossing on 09/17/2012 21:55:53 MDT Print View

Handcarts have been pulled long distances over this country a very long time ago, so it can be done. Lighter carts using modern materials will help. I don't think wider wheels are necessary, although I'd want strong big diameter wheels.

alastair humphreys
(alastairhumphreys) - MLife

Locale: UK
a bit more info on 09/18/2012 03:01:58 MDT Print View

Hi all,
Thank you for your feedback.
The desert I am going to will mostly be flattish gravel pans and low plains. There are some huge dunes too (and I know that I will need to shuttle carry everything on that phase and that it will be very slow and very hard).
I am looking at a 4 wheel cart with MTB wheels for hauling the water and gear. We will both pull the one cart.

Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
Four wheels? on 09/18/2012 06:28:00 MDT Print View

Hi Alistair,

I'm wondering about the rational for four wheels. I would expect this to be much harder to steer, and to be more affected by the rough stuff you're likely to encounter. Soft sand is also likely to be a problem. Admittedly I haven't done a lot of pushing of four wheels, but I have done a couple of thousand km of desert cycling in Australia and Mexico, (of which maybe fifty km involved pushing)

Any cart I have seen for desert travel has always been a two wheeler, like a sulky or gig. The options on wheels are for MTB or motorbike wheels or smaller diameter balloon tyres

Shows the cart Warren and Charles used, pulling 250kg over about 500km of mostly sand. My experience on sand is that it's all about the flotation, and big tyre bags and low inlflation are crucial.

The advantage of the Chinese wheelbarrow is that only a single wheel track is required, and that it is designed to take that sort of weight. I'm assuming about fifty to sixty days. If you're thinking non-resupply, you're looking at closer to five hundred kg(1000 lb) with food and gear. If you know someone with a spare wheel for a DC-10 I reckon you might be in business!! Relatively light, balloon tyre with a flexible casing that will take the weight easily. The other advantage with this is that you have one of you in harness out the front, and one on the shafts at the back pushing and stabilizing. It lets you mix it up a bit and steer around and over obstructions more easily. The wheel takes 100% of the weight.

A modern example of this is the MRT stretcher wheel, that allows you to carry a 140kg patient with two people over extended rough terrain. Not sure about the 300 kg limit though, or the flotation over sand. You might consider taking one each, which would give you good maneuverability over difficult terrain, allow you to double up for the really rough stuff, and give you some good redundancy if required. Less of a team effort though.

As far as shelter goes, I strongly agree with Nick's post in the other thread to avoid zippers. Fifty days use in sand will kill them. A shaped tarp is probably a great way to go for minimal faffing around. Maybe an oversized trailstar, since it doesn't have a zip, but you can pitch it all the way to the ground if required. A solid inner can be very nice when the winds get up, but if you have a valance you may get away without. Something like an MSR Twin Sisters or even Twin Brothers might also work.

Keep in mind that if there is no shade, the desert floor will be VERY hot, even when you put your shelter up at midday. If there is anyway to design the cart that you can rig the shelter over it, and use it to as a sleep platform for a siesta, you will be much more comfortable. Even getting a foot or eighteen inches off the ground will help. Also check the expected temps at night, and pack accordingly. I remember riding in the predawn with socks on my hands, as it never occurred to me to take warm gloves. A couple of pairs of leather riggers gloves might be worth their weight for warmth, and working hot metal during the day.

For shoes, it sounds old school, but there's a reason they're called desert boots. The suede keeps the rubbish out better than mesh and stays wet with sweat for convective cooling. The sole is stitched on, so there's no glue to melt. And they're not too heavy.

A light coloured cotton or canvas shirt works well. I like to use something with a bit of body to it, as I think it holds the sweat better than a very lightweight one

I hope some of this might help, and I look forward to checking out the video when you're done. I expect to see a swim in there somewhere!


Edited by Rod_Lawlor on 09/18/2012 06:32:39 MDT.

alastair humphreys
(alastairhumphreys) - MLife

Locale: UK
thank you Rod on 09/18/2012 06:35:56 MDT Print View

Thank you Rod for such a thoughtful answer.

Certainly an expedition without a spot of wild swimming is a sad state of affairs. I will do my best...

Our thinking on the four wheel cart is to spread the weight yet still be able to move efficiently when it is not sand. The majority of the trip will be gravel plains though a % will indeed be sand and dunes which will be very hard work.

I like your shelter suggestions - thank you very much.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: A desert crossing on 09/18/2012 10:20:48 MDT Print View

In addition to the other thoughts above, I'm thinking you want to be able to tilt the load or shift the load when you are traversing a side slope. And rather than tilt or shim the axles, I like the approach of shifting some of the load to the uphill side. I don't know if you'd have a single, large container for the water, but I'd be nervous if you are one leak away from losing all the water. If you have multiple jerry cans, then having a rack that lets you shift the outer ones - empties on the downhill side, full ones on the uphill side, would let you traverse a side slope with much less effort because it would track straighter. This could be very simple - straps on the cart or on the cans to hang on a side rail. Or maybe just have enough room inside the box so you can move low-density packs and empty cans around relative to full cans.

For your emergency bug-out option, why not mount padding and straps to a jerry can? Let the can be the structure. You could then also use it for side trips, shadier campsites, or scouting away from your main trailer.

I would modify that cart on the FB page (in a lot of ways, but including) removable extensions to the front upper member of the box so as to have "handlebars" to push/lever it through the nastiest spots.

Editted to add: while pulling in a harness has some advantages, if you had handlebars to push, then it would be easy to rig umbrellas from the cart for shade.

Speaking of umbrellas - if you have four posts a few inches above your load, you can stretch a white or silvered fabric over your load with an air gap and greatly reduce the solar heating of you load. Conversely, you could get a lot of heating/cooking for free while you travel and save time in camp if your meals are already cooked in a solar heater. And/or intentionally let some jerry cans heat up during the day, insulate them at night, and use them as bed warmers in the early morning.

Edited by DavidinKenai on 09/18/2012 10:26:15 MDT.

R... ...
(RogerDodger) - F

Locale: (...)
it doesn't exist, but you should invent it on 09/18/2012 16:23:16 MDT Print View

I'm thinking about that movie Dune, water is scarce they wear body suits to harness and filter (reverse osmosis?) the body sweat and presumably the other body fluids, into drinkable water.

it doesn't exist in the current world market, regardless of -whats-his-name-p-drinker-

but if you are looking to haul that large volume of water, with access to desert heat and a carriage, there is potential for a rev osmosis filtration system.

Read into Les Stroud's Vegetation and Solar Stills. some useful amateur Youtubes.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: it doesn't exist, but you should invent it on 09/18/2012 17:36:45 MDT Print View

Or just a solar still using urine as an input.

I know I drink (water!) to excess in hot climates and am gratified to see lots of clear urine as a result. But I've never had to balance that against a month of consumption. Titrating things a little closer could save weight, for sure.

R/O works great, but is spendy to buy ($1000-ish for sailboat equipment) and a power hog. The pressure can be generated by manual labor or by electricity. I'd suggest doing some research at and comparing the extra cost/effort versus the weight savings. Here are a few datapoints from an older catalog:

1.2 gph manually-powered R/O unit, 7-pounds, $2000

A similar output (1.5 gph) in an electric model pulls 4 amps at 12 VDC and costs $3400. A 4.7 amp solar panel (80 watts) costs $800, weighs about 16 pounds, and measures 48" x 22".

Figuring 5 hours of sun per day (you could better if you cock the panel towards the sun), you'd get 7 gallons per day of water (58 pounds) in return for carrying 23 pounds of gear. That's a pretty big win! Your limiting factor would be urine especially since I don't know what the bypass ratio is (how much seawater is consumed to make a gallon of fresh water - at sea, seawater is pretty unlimited).

But with a highly efficient R/O or a solar still, at least you could drink to excess, knowing that urine could be recycled.

I suspect the best solution (low cost, low weight, highly efficient) would involve getting the urine hot (easy to do) and using cold water (potable water allowed to cool at night) to condense the water vapor.

Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
Shattered on 09/18/2012 18:38:34 MDT Print View

I'm sorry, but I find it hard to believe that I'm reading this stuff here on BPL. At what stage did we think it was right to start filtering or RO urine to save on water carried.

Clearly the answer is to drink the urine straight and avoid all the associated gadgetry! Even cycling hard through the desert for eight to ten hours the most water I used was eleven liters a day, so David's seven gallons is at the high end. I figure that urine concentration is lowest first thing in the morning, so a litre there should get you started. If you make coffee with it, your 9 am litre output should also be pretty clear. I'd change to a fresh litre for consumption at this stage. Use the litre output with lunch, mixed with drink powder. I reckon the afternoon output is likely to be too concentrated for consumption, but there should be another litre before bed that helps to rehydrate over night. True, it's not the full eleven litres, but there is still only a litre or two of waste!

Actually of the eleven litres in, I reckon I only peed six to eight out. The rest went on sweat and respiration so RO isn't quite as attractive as it first looks. On the other hand, maybe I'm just taking the pi ss.


Brian Camprini
(bcamprini) - MLife

Locale: Southern Appalachians
Re: Re: it doesn't exist, but you should invent it on 09/18/2012 19:29:18 MDT Print View

Really cool idea, David. But I'm not sure it'd work for tech and practical reasons. I'm not an engineer, but what little I know about R/O, it's pretty inefficient, which you alluded to. It takes in much more water than it puts out--I think you only get out about a quarter or less of what goes in. Not a problem in a marine environment, of course. I did some googling and it looks like NASA is using something called Forward Osmosis which is much more efficient. I doubt that stuff is commercially available, but I don't really know.

The biggest obstacle to me, though, is betting your life on tech stuff. I know several long distance sailors and even the ones with the latest R/O gear on board top off their water tanks before leaving port. If the system craps out, you have to go old school. And if the GPS dies, a map is rather nice to have.

Really an interesting approach, though, and a great idea. I'd like to think it'll be possible at some point.

Jim Colten
(jcolten) - M

Locale: MN
Re: A desert crossing on 09/18/2012 20:02:00 MDT Print View

Keep in mind that urine is not your only water output. Distilling or purifying urine will not reclaim water lost via respiration and perspiration.

Hk Newman
(hknewman) - MLife

Locale: Western US
Re: A desert crossing on 09/18/2012 20:19:49 MDT Print View

Since you are hauling your load on wheels, you might want to consider 2 tarps, with a little room between both, as one will still transmit heat to occupants underneath in the midday sun. Worked in the desert to cool off my tank crews while waiting for their rides to be repaired (never carried camping gear or tents as they slept in the vehicle). With UL tarps, a little bit more weight, a lot more comfort.

R... ...
(RogerDodger) - F

Locale: (...)
Re: Shattered (reply to Rod) on 09/24/2012 15:27:00 MDT Print View

every couple of years, the same news headline hits the TV on slow news days.
Los Angeles residents are drinking their own pee in tap water!

of course that headline is for sensationalism, but it is partially true.

Southern California is a desert. We import the water supply from other states. The rare rain water goes straight to the ocean to avoid flash flood damage.

The solution? No. Not whats-his-name on the fake adventure channel. The water company claims to filter and process the sewage flush and bath water into drinkable potable water. Every few years when the scandal re-appears, the mayor and the water company execs do a proof of concept and taste test, and drink up the clean clear water.
The joke was most water testers preferred "Eau de Robinet" over Evian and Perrier.

"Eau de Robinet" is french for water of the faucet, but it sounds expensive!

More on that repeating scandal, is that in the UK, the average male's sperm count has been decreasing radically, that the unproven conspiracy theory is that the female hormones from birth control pills that are being urinated, and being recycled into drinking water, and men are indirectly drinking women's birth control.
The water company stated that there is no way for them to filter out the hormones in the water.

Another conspiracy theory is that the hype is possibly generated by carbonated drink and bottled water companies, to regain some business lost to faucet water.

Anyway, my point is that this is not news. It's a far distance from the scandal of drinking pee. but there is recycling going on, and making it back into the water supply of some major cities.