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Two CF straight tent poles compared

March 08, 2021 — BarryK

The last overnight hike, tested a cheap tipi-bivi style tent, designed to be held up with a trekking pole, or any approximately 125cm straight pole. I used a 5-section carbon fibre (CF) pole purchased from Aliexpress, weight 92g:

https://www.aliexpress.com/item/32918962406.html

It is just over 28cm folded, which is great, as fits horizontally in the Daylight waist pack. Anyway, here is the report on that hike:

https://bkhome.org/news/202102/waist-pack-hiking-test-2021.html

The pole is too long for that tent. Next, plan to test the other cheap tent purchased from Aliexpress, a tarp-tent. That might be more agreeable with the 125cm pole, however saw a shorter one online, 114cm, decided to buy that.

I bought the pole from backpackinglight.com.au, Six Moon Designs 5-section 45" (114cm), and it arrived today. I was quite surprised how fragile it looks. Only weighs 60g, and I can see why. Here are the two poles side-by-side:

img

...the new one is on the left.

I was unable to find any reports of the thinner pole breaking, but it does bend. In fact, it is intended to bend. I looked up the Six Moon Designs website:

https://www.sixmoondesigns.com/products/5-section-pole-45-carbon-fiber

Carbon Fiber poles do have built-in flexibility. When setting up your shelter, you want to tighten the canopy just to the point where the poles create a slight bend. Then back off until vertical. This is more than enough tension to keep your shelter erect, even with high wind loads.

On the other hand, the Aliexpress web page states that their poles are intended to remain rigid and straight.

Going back to the 80s, I have had prior experience with carbon fibre poles. Bought a very cheap tent with two carbon fibre poles, that formed hoops either end of the tent. So it was a tunnel design.
Problem was, the carbon fibre started to crack at the joins. The fibres run lengthwise, so once the cracks started, it rapidly split down the pole.

Apparently, modern CF is manufactured with criss-crossed layers, so much less likely to split. This page explains:

https://bushwalkingnsw.org.au/clubsites/FAQ/FAQ_Shelter.htm#Poles

Only using my measuring tape, so these measurements are approximate:


Diameter
Wall thickness
Aliexpress pole
10mm
1.5mm
Six Moon Designs pole
8.5mm
0.7mm

Perhaps the Six Moon Designs pole is made with the highest quality technique, so can withstand flexing. Even so, just looking at it does not fill me with confidence.

I intend to test both in the field.  

Tags: light

Single-wall hybrid tents

March 08, 2021 — BarryK

I mentioned single-wall and single-wall-hybrid tents a few days ago:

https://bkhome.org/news/202103/reconsidering-tent-in-waist-pack.html

Here is a video of a Zpacks hybrid tent. These things cost over five hundred US dollars:

https://www.youtube.com/watch?v=wZht9_iKyXk

What that video shows is the horizontal mesh strip along the base, between wall and bathtub floor. The idea being that water will fall through the mesh rather than run into the bathtub floor.

That tent also has one wall of mesh, with outer fly, so it is a hybrid design.

There is a small weight reduction, compared with dual-skin tents, however I do not think that it is worth the hassles it brings. There are some comments from experienced hikers here:

http://www.walkingforum.co.uk/index.php?topic=36678.0

Quoting 'marmottungsten' from above link:

You can be the most competent camper in the world, you will never be able to stop condensation in a single wall tent, especially ones made of DCM, like the Zpacks tents...It may be waterproof, but it isn't exactly breathable, so without leaving the door or doors open a bit, even in the rain, there is nowhere for moisture in your breath to go except onto the inner surface of the tent wall.
 The driest tents are two wall tents which have an inner tent that is mostly made of no see-um mesh. 
The mesh is highly breathable, allowing moisture to pass through and be carried away by the slight draught that the design sets up between the inner and outer walls, before it has time to condense on the inside of the rain fly.
 Most of the best new tent designs utilise mesh inner's as it is the most effective method to stop condensation.  Two wall tents are heavier though, so it comes down to whether you prefer to carry a lighter base weight or being able to enjoy a dry nights sleep.

Well, it doesn't have to be raining. Overnight, the temperature drops and humidity rises, and your breath and evaporated sweat condense on the outer tent inner-wall. Or, as 'marmottungsten' has said, the moisture might get carried away in the slight air current between the two walls. Even if it doesn't, it will condense on the outside inner-wall.

It is normal for the outer skin, the fly, to be damp in the morning, on the outside and sometimes a bit on the inside. Letting it dry out before packing it, is pretty normal practice.

Thinking back, I don't recall ever having dampness on the inside of the fly, only the outside, so just leaving the tent erected for awhile after sun-up was sufficient to dry it.

Or, you could probably hurry the process by taking it off and giving it a shake, then drape it over the tent or a branch for awhile.

A single-skin tent, however, there is going to be moisture inside the tent, which can be difficult to dry out.

However, there are super-ultralight hikers who use these hybrid tents, and cope with the condensation. But I think that you would need to do a lot of research before deciding to go that way. 

Tags: light

Why do we have magnesium deficiency?

March 06, 2021 — BarryK

I posted about cramps in the feet and legs while contorting around inside a small tent on the last hike:

https://bkhome.org/news/202102/waist-pack-hiking-test-2021.html

I take a magnesium tablet about every third day, which is effective at preventing leg cramps. if I don't take the tablets, I will wake up in bed with painful cramping. Also, the feet will cramp during the day, especially if they get a little bit cold.

I know of two close relatives who also have to take magnesium supplements, due to cramping. Haven't asked other relatives, but I assume it is a widespread problem.

Sometime ago I investigated iodine deficiency, which is a worldwide problem, or rather, used to be. I don't have the links, but there is an Australian academic who spent most of his life studying iodine deficiency, and he also took part in programs in China and other countries to study and eliminate deficiency.

The fundamental problem is that iodine has leached out of soils and ended up in the ocean. Especially in Australia, which is a very ancient continent. Sea food is rich in iodine. Animals and plants inland are deficient.

Here in Australia, the practice was to wash milk bottles and other food preparation containers, with iodine, which meant that most Australians were getting sufficient iodine, without realising it. The medical fraternity didn't realise it either, until they began discovering iodine deficiency in infants -- then they discovered it coincided with an Australia-wide switch from iodine to chlorine to wash bottles and other food preparation containers.

One of the outcomes was introduction of iodine into salt. Unfortunately, there are those in Australia who only use non-iodized salt, nor do they eat bread and other processed foods that contain added iodine. I know one of those people -- and she mentioned awhile back that her doctor had diagnosed goitre, a symptom of iodine deficiency.

In China, having a totalitarian regime, the government simply ordered that all salt was to be iodized, no exceptions.

Anyway, back onto magnesium. I found a fascinating academic paper:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786912/

A few quotes from it:

Because serum magnesium does not reflect intracellular magnesium, the latter making up more than 99% of total body magnesium, most cases of magnesium deficiency are undiagnosed. Furthermore, because of chronic diseases, medications, decreases in food crop magnesium contents, and the availability of refined and processed foods, the vast majority of people in modern societies are at risk for magnesium deficiency.

....

‘The homeostatic mechanisms to regulate magnesium balance were developed millions of years ago. Investigations of the macro- and micro-nutrient supply in Paleolithic nutrition of the former hunter/gatherer societies showed a magnesium uptake with the usual diet of about 600 mg magnesium/day, much higher than today’. Our homeostatic mechanisms and genome are still the same as with our ancestors in the Stone Age. This means our metabolism is best adapted to a high magnesium intake.

In developed countries, the average intake of magnesium is slightly over 4 mg/kg/day. More than a quarter of obese and non-obese youth have inadequate intakes of magnesium (27% and 29%, respectively). The authors of a study concluded: ‘Even though children may consume an excess of energy, they may not be meeting all of their micronutrient needs’. In other words, children are overfed and undernourished. One expert has argued that a typical Western diet may provide enough magnesium to avoid frank magnesium deficiency, but it is unlikely to maintain high-normal magnesium levels and provide optimal risk reduction from coronary artery disease and osteoporosis. That is, ‘Various studies have shown that at least 300 mg magnesium must be supplemented to establish significantly increased serum magnesium concentrations…’ In other words, most people need an additional 300 mg of magnesium per day in order to lower their risk of developing numerous chronic diseases. So while the recommended daily allowance (RDA) for magnesium (between 300 and 420 mg/day for most people) may prevent frank magnesium deficiency, it is unlikely to provide optimal health and longevity, which should be the ultimate goal.

.......

Since 1940 there has been a tremendous decline in the micronutrient density of foods. In the UK for example, there has been loss of magnesium in beef (−4 to −8%), bacon (−18%), chicken (−4%), cheddar cheese (−38%), parmesan cheese (−70%), whole milk (−21%) and vegetables (−24%). The loss of magnesium during food refining/processing is significant: white flour (−82%), polished rice (−83%), starch (−97%) and white sugar (−99%). Since 1968 the magnesium content in wheat has dropped almost 20%, which may be due to acidic soil, yield dilution and unbalanced crop fertilisation (high levels of nitrogen, phosphorus and potassium, the latter of which antagonises the absorption of magnesium in plants). One review paper concluded: ‘Magnesium deficiency in plants is becoming an increasingly severe problem with the development of industry and agriculture and the increase in human population’. Processed foods, fat, refined flour and sugars are all devoid of magnesium, and thus our Western diet predisposes us to magnesium deficiency. Good dietary sources of magnesium include nuts, dark chocolate and unrefined whole grains.

The magnitude of this problem has been going on "under the radar" by most of us, and even, I read, medical practitioners are not sufficiently aware.

I know an elderly person who was prescribed three tablets per day by her doctor. When she told me that, I thought, wow, isn't that over the top, might she be getting too much? However, from the quote above, our bodies are designed to handle huge intake of magnesium.

The paper also mentions that magnesium intake requirement is higher in the elderly. I found a table showing how recommended intake increases with age:

https://www.healthline.com/nutrition/magnesium-deficiency-symptoms

AgeMaleFemalePregnancyLactation
Birth to 6 months30 mg*30 mg*

7–12 months75 mg* 75 mg*

1–3 years80 mg80 mg

4–8 years130 mg130 mg

9–13 years240 mg240 mg

14–18 years410 mg360 mg400 mg360 mg
19–30 years400 mg310 mg350 mg310 mg
31–50 years420 mg320 mg360 mg320 mg
51+ years420 mg320 mg

I take Blackmores MagMin, the active ingredient per tablet is "Magnesium aspartate dihydrate 500mg (Magnesium 37.4mg)". So what does that mean, am I only getting 37.4mg in each tablet?

A word of warning: despite the above academic paper stating that we can tolerate a large intake of magnesium, I did come across warnings, while browsing online, of possible side-effects if too much is taken.

EDIT 2021-03-07:
Very interesting, I have received emails from Stephen, David and Rodney, advising me that a contributing factor to muscle cramps is lack of salt, that is, sodium chloride. Quoting Rodney:

In 1973 I worked in tropical Indonesia for 10 months. with a company crew of tv transmitter installation engineers.
We were warned while there, to liberally sprinkle extra salt on our meals to supplement the body salt lost through sweating in high temperatures.
Westerners will easily keel over otherwise.
As you say, leg cramp is another side issue of magnesium deficiency.

Quoting from here:

https://www.mayoclinic.org/diseases-conditions/muscle-cramp/symptoms-causes/syc-20350820

Too little potassium, calcium or magnesium in your diet can contribute to leg cramps.

It is recognised that most of us eat too much salt, however, I will experiment with this on the next hike, maybe take along a packet of potato chips (in the UK, they are called "potato crisps", a fact I learnt when I went into a village general store in England back in the 70s, and asked "do you have any potato chips?" and just got a blank stare).

EDIT 2021-03-07:
The above link mentions lack of potassium as a cause of muscle cramps. See this:

https://www.healthline.com/nutrition/potassium-deficiency-symptoms

...that link advises not to take potassium supplements, as there is danger if take too much. Potatoes have potassium, so that packet of potato chips is looking good! Yum!  

Tags: ethos

Reconsidering tent in waist pack

March 03, 2021 — BarryK

I recently went on an overnight hike with a Daylight lumbar pack, also known as a waist pack, or fanny pack. Blog report:

https://bkhome.org/news/202102/waist-pack-packing-list-for-2021-hike.html

The weight of the waist pack and contents was about 4.5kg, which is too high. I am now going through the exercise of exploring how to reduce the weight. Firstly, I considered the base load, without shelter or sleeping:

https://bkhome.org/news/202102/reconsidering-the-waist-pack-base-load-sans-shelter-and-sleeping.html

...which is 1.31kg.

In this post, I am considering options for the tent. Here is a breakdown of the weight of the Aricxi tipi-bivi-style tent used in the last hike:

Long pole (CF)
92
Short pole
42
Groundsheet
93
Inner tent
310
Outer tent (fly)
290
Stakes & cord
162
TOTAL:
989

So, this post is aiming to bring that figure of 989g down somewhat.

Apart from weight consideration, the tent has issues. There were things that I didn't like, such as constriction when sitting up, difficulty in erecting the fly, and requirement of at least 12 stakes.

Then, being elderly with all kinds of aches and pains, the difficulty of crawling into and out of, and contorting around inside.

I would like to revisit the Big Sky Soul 1P tent, that I used in 2016. Since then, it has been in the closet, however, I do think it is worth another look. The main reason is the ease of access: just step in and step out, no crawling around.

I introduced the Soul tent here:

https://bkhome.org/light/shelter.html

img1

Here is a field test in 2016:

https://bkhome.org/light/field-tests/ft2-backpack.htm

Here is a weight breakdown of the Soul tent:

Poles (aluminium)
317
Groundsheet (tyvek)
83
Inner tent
334
Outer tent
283
Stakes, 4xshort, 2xlong
69
Cord
29
TOTAL:
1115

1115g is a bit on the heavy side. However, there are Duralite carbon fibre poles available from Big Sky, that weigh just 210g, which will bring the total down to 1008g.

The main objective is to get weight off the waist pack, so what if the poles could be carried somewhere else on the body, maybe even strapped across the shoulders? The weight of the tent carried in the waist pack would then reduce to 798g. Very interesting! Just a lateral thought, have to put that one on hold for now.

EDIT 2021-03-04:
Received an email from Bob, owner of Big Sky, informing me that the Duralite carbon fibre poles are currently not available. He didn't say when they will be available.
A possibility, maybe, is to have them custom made -- there are people who do that. Don't have the link, but there is someone in Australia who makes custom carbon fibre poles.
However, curved carbon fibre poles are tricky. They tend to split at the joins, as the fibres run lengthwise. I know about the splitting from personal experience. The feature of the Duralite poles is the fibres are criss-crossed so resist splitting at the joins.

The next overnight test is planned to be with the Aricxi tarp tent, with inner mesh bivi, another cheap tent that I purchased from Aliexpress:

https://bkhome.org/news/202102/planning-equipment-for-next-ultralight-hiking-adventure.html


img2

I used a 125cm folding carbon fibre pole with the tent on the previous hike, but found it to be too long. I have also estimated that it will be too long for the tarp tent, so have ordered this one:

https://www.backpackinglight.com.au/six-moon-designs-5-section-45-carbon-fibre-pole.html

...only 60g and 114cm long. Folds to 28cm.

This tarp is extremely interesting, as there are various possibilities how it can be erected. Here is a table showing two choices:

Groundsheet (tyvek)
80
80
Inner tent
215
215
Outer tent (tarp)
301
301
Stakes & cord
95
95
Extra cord

20
Pole (CF)
60

TOTAL:
751
711

These two choices are with or without the carbon fibre pole. Without, there would have to be two conveniently-spaced branches, to which cords can be attached. The tarp ridge-line can be held up by cord at each end. I have estimated an extra 20g cord, but that remains to be seen in the field.

Two possible weights, 751g or 711g. I plan to take the pole on the next hike, but extremely interested in exploring pole-less erection.

The potential is that weight of shelter will be reduced from 989g to 711g, which is a reduction of 278g.

Adding 711g to the previous tally of 1314g, the grand total is now 2025g, 2.025kg. This is potential, need to get out there in the field and test.

EDIT 2021-03-4:
I received an email from Jon, with a link to a light weight tent sold by Paddy Pallin here in Australia. The thing is, though, it achieves the light weight by being single-skin.

If you are interested in shopping around for a tent, it is important to be aware of the difference. This was my reply to Jon:

Thanks for the info. The problem is, it is a single skin tent.

There are a lot out there that will bring the weight down, but are
only single skin.

I know the value of a double skin tent. Have often camped when there
is heavy condensation overnight, and the condensation forms on the
inside of the outer tent, not on the inner tent.

With the single skin tents, the condensation forms on the inside and
runs down onto the tent floor. Plus, if the sleeping back touches the
side, it gets wet.

There are some single skin designs from specialist tent manufacturers
in the USA, super-ultralight, with a band of horizontal mesh around
the bottom to separate the floor from the walls, so moisture running
down will fall through the mesh and not run onto the floor. They are
very expensive, and still a compromise as the inside walls will get
wet.

Another consideration is ventilation in our hot Aussie weather. Many summer nights, you want all the cooling breezes that you can get, plus you want to keep the bugs out. Hence, the mesh inner tent is essential!

Having said that, if weight reduction is your highest priority, you might be prepared to put up with condensation on the inside walls and extremely limited ventilation. That is a choice made by some super-ultralight hikers.

Just remembered another type of tent, known as a "hybrid tent". This is single-skin but has one mesh wall with outside fly flap. In some cases there is mesh with fly flap on two sides. This is very much a compromise.     

Tags: light

Protect hands from mosquitoes at campsite

March 02, 2021 — BarryK

On the last overnighter, arrived at the shelter in the early evening, and observed that whenever stopped moving, it would not be long before there were mosquitoes buzzing around. They mostly go for the ears and back of the hands.

So, put on the head net, and tucked the pants into the socks. Problem fixed ...except for the hands.

If don't want to use insect repellent, what protection is available for the hands? Bug netting to cover the hands? Special gloves?

I have gloves, but they are for warmth. Gloves are needed that are suitable for wearing in hot weather. First look online, found this:

https://mosquitonetsusa.com/products/bug-mittens

img1

I looked on eBay and Aliexpress, and there are complete mesh outfits, for the entire body, for example:

https://www.aliexpress.com/item/1005001279785122.html

img2

eBay also has the mesh mittens available individually.

Another possibility are "sun gloves", designed for UV protection, for example:

https://www.coolibar.com/unisex-uv-gloves-upf-50.html

https://www.simmsfishing.com/bugstopper-sunglove-7

Other possibilities are driving gloves and fishing gloves.

Lots to be found on eBay. For example, these half-finger cotton gloves:

https://www.ebay.com.au/itm/Male-Accessories-Men-Sun-Gloves-Sun-Block-Outdoor-Simple-Anti-UV-Protective-CH/133654807690

img3

But perhaps cheap cotton gardening gloves would be adequate, and not too hot. The mesh mittens would have the advantage of very light weight and compactness for hiking. On the other hand, half-finger gloves would be good for using items such as the mobile phone.

EDIT:
I discovered that there is another type of glove known as a "glove liner". These are gloves that are designed to go inside gloves. An example is to go inside boxing gloves. As these are fairly thin and close-fitting, they are also advertised for use in delicate work, such as handling jewellery.

I found many of these on eBay, and individually they are so cheap that I decided to take a punt and order a couple.

These cost just AU$2.60 including postage:

https://www.ebay.com.au/itm/White-Cotton-GLOVES-BOXING-Inners-Sweat-liners-hygiene-wrist-cuff-washable-new/254704866976

These cost AU$3.10 including postage:

https://www.ebay.com.au/itm/COTTON-WORK-GLOVES-KITTED-CUFF-LINER-HAND-PROTECTOR-JEWELRY-HANDLING-1-PAIR/154330600283

img4

There are others that don't have that wrist band, but it looks like that will be handy to tuck the shirt sleeves into.

It remains to be seen whether these will be OK in hot weather, but I reckon worth a punt given the prices. I would be wearing them at campsites evening and overnight, so it will be cooler. They may also be suitable to replace the gloves that I have currently included in the pack for cold snaps.

Note, there are also glove liners at specialist camping stores, at AU$40+ each.   

Tags: light

Only the USA, Liberia and Myanmar still use imperial weights and measures

February 25, 2021 — BarryK

Here in Australia, we get those TV shows from the USA, house restoration, building off the grid, etc., and I find it amusing when they talk in imperial units.

For example, they will measure a length of timber as 5 foot, 3 and 3/8 inches. The thing is, math calculation is messy when doing it in fractions. It is also messy to have non-metric conversions, for example 12 inches equals 1 foot.

Then there is ounces, which could mean a weight or a volume. Messy again.

And of course there is degrees Celsius -- so much neater to have zero degrees the freezing point of water, and 100 degrees the boiling point.

Australia converted to the metric system of measurements in the 60s, and today I wondered what countries in the world are still using imperial measurements -- got reminded of this today when publishing weights in grams in the previous blog post.

According to this link, only the USA, Liberia and Myanmar:

https://www.statista.com/chart/18300/countries-using-the-metric-or-the-imperial-system/

However, most countries that were previously part of the British Empire are still using imperial measurements here and there. There are some measurements where it was just more convenient to stay with imperial. TV screen size for example.

The UK, where the imperial measurements originated, is still using miles-per-gallon, and gallons when filling up the petrol tank.

There were apparently moves in the USA to become metric, and I wonder why it didn't happen. I was in high school here when it happened, and I recall the government mandating that things like measuring tapes had to become metric -- in other words, the Federal Government forced it to happen. In the USA, the homeland of the "rugged individual" and "free will", perhaps the government did not have sufficient authority (or cohesiveness, or motivation) to force it? or were the State governments insufficiently aligned to force it to happen? Just speculating.

EDIT 2021-02-26:
David, in the UK, commented:

We buy petrol in litres but range is mpg. We buy beer in the pub in pints but litres in cans.

John G., in the UK, clarified that petrol has been sold in litres since the 1980s:

In the UK petrol has been sold in litres, rather than gallons, ever since the 1980s! See https://ukma.org.uk/the-case-for-change/problems-arising-from-two-systems/fuel-consumption/

For fuel consumption, the UK still uses miles per gallon rather than miles per litre or even kilometres per litre. Bizarrely the EU uses an inverse measure, litres per 100 kilometres.

Yes, we also use litres per 100km here in Australia. The link sent by John G. is very interesting, it has information about Australia:

https://ukma.org.uk/what-is-metric/australian-experience/

...which shows conversion milestones in 1971 and 1974. My memory, though, is of conversions happening while I was still in high school, in the late 60s.

Now I'm curious, is my memory faulty? Found this:

https://en.wikipedia.org/wiki/Metrication_in_Australia

...ah, it started in 1966, with change from pounds, shillings and pence, to dollars and cents.

The Wikipedia also explains the situation in the USA, Canada and the UK:

https://en.wikipedia.org/wiki/Metrication_in_the_United_States

https://en.wikipedia.org/wiki/Metrication_in_Canada

https://en.wikipedia.org/wiki/Metrication_in_the_United_Kingdom  

EDIT 2021-02-28:
David W. in the USA commented that the US has embraced metrication somewhat:

I'm in the States, and do recall an attempt in the mid-1970s to sell
gasoline by the liter, but it failed -- I believe because of massive
pushback by the public.

Since then it's been a series of baby steps. Goods are often labeled
with both imperial and metric measurements, in that order.

Speedometers have been labeled with miles *and* kilometers for decades.

The only metric measurement I can recall Americans having more or less
fully embraced is vehicle engine size. You basically don't hear it
referred to in cubic inches anymore, just liters. And of course,
Americans have fully embraced motorcycle engine sizes in cubic
centimeters for at least 50 years.

Yes, engine sizes in litres ("liters" in the US) is something that I noticed on those TV shows from the US where they restore old cars, or greatly enhance a car. Just looking at Channel 96 here in Perth: "Garage Squad", "Overhaulin", "Diesel Brothers" -- shows from the US. There is one from the UK, "Wheeler Dealers" -- where I picked up the info about the UK is still using miles and mpg.

Michael A. in Australia commented that the car manufacturers probably pushed back metrication attempts in the US:

You have to take into consideration that back in the 60s/70s the BIg 3 car manufacturers here were GM, Ford and Chrysler (Leyland was a drop in the bucket, plus a couple of others like Lightburn - niche car really)  - I'm sure they would have pushed back _hard_ against metric, extra cost involved in converting speedometers, fuel gauges etc.

So I believe that metric wasn't mandated for cars until 1974, and that is about the time we saw 'speed limit 35' signs disappear replaced by 60 within the red circle. I was 9 years old then! 

I had assumed that NASA, a scientific organization, would be using metric units, but did a check today and found that is not so, they use a mix of imperial and metric:

https://en.wikipedia.org/wiki/Metrication_opposition

On 29 March 2010, NASA decided to avoid making its proposed Constellation rocket system metric-compliant, especially due to pressure from manufacturers; ultimately the program was discontinued. It had been predicted that it would cost US$368 million to convert to metric measurements for parts made by both NASA and external companies. Constellation would have borrowed technology from the 1970s-era Space Shuttle program, which used non-metric measurements in software and hardware.[16] NASA's non-compulsory position has contributed to at least one major mission-failure: in 1999, a contractor's use of pre-metric units caused the disintegration of NASA's $328 million Mars Climate Orbiter.[17] Despite NASA's non-compulsory policy, commercial space manufacturer SpaceX currently designs its systems (e.g. Dragon and Falcon 9) using metric units.

...that has really surprised me. Good that SpaceX is using metric units.  

EDIT 2021-03-01:
Feodor commented about the US auto industry:

GM in Detroit experimented with the metric system in the 1970th. Yes, it failed
when imperial screws, washers and nuts got mixed up with metric counter parts.
Same problem existed with the 1/2" tools for the metric system. A friend of my
parents named Karl Bohmer who lived in Windsor/Ontario worked all his life for
GM in Detroit. His job was to fix every thing that showed up broken at the end
of the assembly line. He was very happy when that metric mixing match ended. 

EDIT 2021-03-2:
Amitav commented from India:

Very interesting discussion on Metric and Imperial units! In India, everything is in metric, as we are a relatively young country. With one exception: The Aviation industry seems to still work in Imperial! I started as an engineer in the automotive industry, and my company started its first aerospace products in 2014. One big - and annoying - barrier was suddenly everything, including even nut and bolt sizes, had to be in Inches, and weird fractions :) . I would be interested to know if the Australian Aviation Industry use Metric measures?

I imagine that it would be mixed, as Australia acquires a lot of aviation (and military) hardware from the USA. Did a quick search, Found this at a technical college:

https://www.swinburne.edu.au/study/courses/units/Aircraft-Design-and-Operations-AVA20006/local

Exposure and use is given to imperial and metric units as used in the aviation industry.

After successfully completing this unit, you should be able to:
1. to describe how factors such as weight, wing area, engine power, drag and high lift devices effect aircraft performance and to apply basic estimation techniques to determine an aircraft configuration to meet a specified mission,
2. to compose gust and manoeuvre diagrams,
3. to describe the principles behind jet transport performance in an airline environment and how they affect the cost of operation,
4. to be able to use imperial units in basic engineering calculations.

It looks like the same problem as in India. Young people coming into the college course would have mostly used metric units at school. 

Have received more feedback, but calling a stop to this blog post!     

Tags: ethos

Reconsidering the waist pack base load sans shelter and sleeping

February 25, 2021 — BarryK

On the last overnighter with the waist pack, carried about 4.5kg, which is too much. Possibly could use shoulder straps, but would like to explore reducing weight enough so that the tensioning straps on the waist pack will be effective to stop bounce.

Also the hip belt and tensions straps should be sufficient to stop the pack from sliding down, without having to tighten the hip belt to the point where it becomes uncomfortable.

This post is reconsidering the base load, leaving out everything that either isn't absolutely needed, or can potentially be replaced with something lighter. Shelter and sleeping items will be out.

So, the photo of the items becomes this:

img0

The weight of what remains is 1403g.

Before considering alternatives to the tent, sleeping bag, etc., can this 1403g be reduced? Let's see...

Bathroom kit

This was 73g, now 71g after brushing the teeth on the last-weekend hike. Here are the contents:

img1

Listing the contents:

  1. Toothpaste
  2. Fix-o-mull tape
  3. Toothbrush, with head enclosure
  4. Antiseptic wipes
  5. Bandage(s)

The heaviest item is the toothpaste, at 47g. I cut it down to 39g:

img2

...the tube is plastic, and attempted to melt the end on a stove hot plate, however, the inside looks like it is metalized and it didn't melt together.

Dentists sometimes have sample tubes of 25g or thereabouts, and perhaps they are available on eBay.

Antiseptic wipes in individual sachets are readily available from pharmacies. I have "Povidone Iodine swabs", not because they are particularly good but because they are the only type my local pharmacy stocks. Haven't tested them yet.

Fixomull (sometimes known with hyphens, fix-o-mull) tape goes by various names, but my pharmacist knew what I wanted when I asked for it by that name. It is a very small roll.

Head enclosure for a toothbrush is also readily available. You might find them in those knick-knack stores, like RedDot here in Australia, also on eBay. They are just little plastic containers that snap over the toothbrush head, and probably you would have to buy a set of them, even though you only want one.

The weight of the bathroom kit is now 63g.

Kitchen kit

Made the decision not to do any cooking on these short hikes, so the kitchen kit is minimal:

img3

Listing the items:

  1. Sea 2 Summit plastic spoon
  2. Pill holder
  3. Collapsible silicone cup
  4. Folding knife
  5. Disposable plastic knife

The total weight is 81g. The folding knife is 25g, but do I really need it? Decided no, so have taken it out, and the total weight is now 55g.

Electrical kit

I carry a phone in a pant pocket, and the electrical kit has support parts for it, as well as a tiny headlamp:

img5

Total weight is 102g. Item list:

  1. Headphone "earpods"
  2. USB-A male to USB-C male cable
  3. USB-A male to micro-USB male cable
  4. USB flash drive and OTG adapter
  5. Mains power charger
  6. Headlamp

My phone has a USB-C charging socket, the headlamp has a USB-A male charging plug, so can get rid of item 3.

The solar panel and mains charger both have a USB-A female socket, so either can be used as a charging source.

The headlamp is tiny and lightweight. It is rechargeable, with a USB-A male plug. I attached a ribbon as a headband, and total weight is 16g. Back in 2016, these tiny torches were available from various online vendors. I bought it from DealExtreme, but it is no longer there. Ah, eBay has something similar, search for "torch rechargeable keyring".

Just realised that if want to charge the headlamp from the solar panel, due to the USB-A female socket being flush with the panel, will need a short USB-A male to USB-A female cable. Adding 17g.

The collapsible silicone cup was available all over the place in 2016. I bought mine from Kmart.

The phone has a micro-SD card, so really do not need the Flash drive and OTG adapter. Remove items 3 and 4, added a cable, and the weight becomes 94g.

You might be thinking that these weight reductions are negligible, and you would be right. Anyway, keep going, see if can get the reductions to add up to a non-negligible amount...

Sawyer filter

I consider this to be essential, to filter water from the rainwater tanks at shelters, or from dams, ponds and streams. Especially since I intend to carry very little in bottles. Weight 114g. Here are the components:

img6

The straw is for drinking direct from pond etc (through the filter of course).

The collapsible bottle is filled with dirty water and then squeezed through the filter -- except that the instruction to "fill the bottle" printed on the outside, can be a challenge, as it wants to stay flat. This seems to be the weak point in the whole system.

The syringe is for back-flushing clean water through the filter, to wash out accumulated particles. That can be left at home. It doesn't weigh much, but occupies a lot of space.

That squeeze-system flat bottle remains the one annoying thing. Easy to fill from a rainwater tank, but not from pond or dam. Will have to live with it.

So, only taking out the syringe, the total weight is 82g.

Toilet kit

This consists of a small roll of toilet paper and titanium trowel. I bought the trowel several years ago, from the USA, a guy who made them in his garage. There are plenty of alternatives.

Warm layers

The photo at top of this post shows puffer jacket, windcheater and beany. Regarding the beany, there are lighter ones, designed for hikers and cyclists, about 50g, so intend to shop around for one of those.

Thinking about coping in a cold spell, gloves would be good to have. I have a pair that are very warm and lightweight, only 60g, so although this post is supposed to be about reducing weight, have added the gloves.

Estimated weight of beany and gloves will be 110g.

Base load total

Adding them up:

Daylight pack
408
Puffer jacket
192
Windcheater
95
Beany & gloves
110
Water bottle
57
Water filter kit
82
Toilet kit
38
Bathroom kit
63
Kitchen kit
55
Electrical kit
94
Compass
4
Solar panel
92
Head net
24
TOTAL:
1314

Total weight carried in the Daylight pack, including the pack itself, is 1.31 kilograms.

Note that insect repellent is not included in any of the kits. This is because I have always taken it, but never used it. I prefer just to put on the head net.

In the next blog post, I plan to consider alternative, and possibly radical, lightweight alternatives for shelter and sleeping.  

Tags: light

Lumbar support while sitting in a tent, take-2

February 24, 2021 — BarryK

Having a degenerated lower vertebrae, that can slide out of position if the posture is wrong, it is a challenge for me to camp in a small tent. Sitting cross-legged in the tent, the spine has to be kept erect, which becomes tiring after awhile.

A possible solution is some kind of mechanical bracing. There is a product called the "Ah Chair", that I considered, and also tested a leverage system with a rope tied to the pant belt:

https://bkhome.org/news/202102/lumbar-support-while-sitting-in-a-tent.html

Neither of those were comfortable for me. So, thought about how the body sits and balances while cross-legged, and came up with another solution...

I purchased this shoulder strap, and it arrived today:

https://www.ebay.com.au/itm/333732948252

img1

...in particular, notice the end fittings. I chose this belt because of those fittings. They will click onto cloth loops, which in turn will loop over the knees.

Fetched ancient jeans from the garden shed and cut two loops off a leg, and here it is, lumbar support solution take-2:

img2

It works! fairly comfortable, the body feels balanced, no stresses sitting like this. Only sat there for 10 minutes and the jury is still out as to whether it is good for longer periods.

The very fact of being cross-legged is a strain on the knees, and even if the back is successfully propped up, pain in the knees will still limit the duration of sitting.

The belt is adjusted to total length of 96cm, much less than the maximum that it can be adjusted to.

My first thought was to loop the ends of the belt, so that separate cloth loops are not needed, but the belt is not long enough. It might work with a child or very small adult.

The cloth loops are approximately 15cm diameter. Tonight I plan to sew the loops to slightly less diameter, so that the belt can be adjusted longer -- the main reason for doing this is the padding at rear is slightly offset from the centre of the back due to the length-adjustment buckle.

Belt and loops add 105g to the load that have to carry, so not sure if I will take it. The belt serves two purposes, also usable as a shoulder strap.

A shoulder strap did come with the Daylight pack, but I lost it. It is useful when travelling on buses, trains and airline carry-on. Paul and Drew on YouTube have reported that it is useful to have it attached while hiking, so as to be able to swing the pack around to the front -- hmmm, that might mean won't have to pack it into the Daylight pack.  

Tags: light