REVIEW: MSR Tindheim 2 - the traditional tunnel tent gets a makeover

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 UKC/UKH Gear 02 Jun 2023

With the Tindheim, MSR have gone back to basics to create a simple but very effective tunnel tent. Sturdy, spacious, and stable in wild weather, this is an easy model to love, says Dan Bailey, but one that might make serious weight savers think twice.  

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 ScraggyGoat 02 Jun 2023
In reply to UKC/UKH Gear:

How did they make something that heavy and still only have a hydrostatic head of 1500 and 3000mm,  for fly and floor respectively?
That’s struck off my list.

3
In reply to ScraggyGoat:

Every time we review an MSR tent the low hydrostatic head thing comes up. I forgot to add it this time. I've used several over the last decade or so and they get a lot of rain and pitching-on-bog action by virtue of this being Scotland. Never once has leakage been an issue. Is HH all it's cracked up to be? Are extra-high figures for tents simply overkill? No idea, but I assure you it's not a concern in this case

 ScraggyGoat 02 Jun 2023
In reply to Dan Bailey - UKHillwalking.com:

Interesting, I’ve had similar HH ratings on Mountain Hardwear and Marmot tents and they have both pressure leaked kneeling or laying on. Whereas higher rated Terra Nova, North face and Robens haven’t. 
So I’ll reserve judgement till I see the MSR, though I’ve seen other MSR tents with the wishbone pole arrangements break in wind.

1
 TobyA 02 Jun 2023
In reply to ScraggyGoat:

I'm reviewing my third MSR tent in about the last 5 years, and haven't had problem with leaking from above or below in any of them except the zoic which didn't come with sealed seams https://www.ukclimbing.com/gear/camping/tents+bivvys/msr_zoic_2_tent-12333 . I'm trying the ultralight Freelight 2 currently, and that must be even lighter on the groundsheet as the whole tent is so light, and I've been lazy/testing it hard and not taking out my normal Tyvek ground sheet protector and still no issues with anything coming through from below.

 TomCooksey 03 Jun 2023
In reply to UKC/UKH Gear:

Looks quite similar to the Macpac Minaret?

 Andy Hardy 03 Jun 2023
In reply to TomCooksey:

But without the bomb proof groundsheet

 OwenM 04 Jun 2023
In reply to UKC/UKH Gear:

Over 3kg, not what I'd call a backpacking tent, even split between two. You could get a better, roomier basecamp tent for that price, so don't really see what use it would be. 

 TobyA 04 Jun 2023
In reply to OwenM:

> Over 3kg, not what I'd call a backpacking tent, even split between two.

But Dan said all in it's not over 3 kgs.

It's not so long ago that 3 kg was pretty normal for a 2 person mountain tent - Pulsars for example. For a spacious and sturdy tent, I'm sure there are plenty of 2 person teams who would be quite happy to carry 1.4ish kgs each. I find the longer the trip, the more willing I am to put up with some extra weight for more liveability night after night.

 DizzyT 04 Jun 2023
In reply to UKC/UKH Gear:

My much missed Vango Spirit 200+ did everything this tent did at 2.7Kg and £130. Well over 100 dry, comfortable nights (being pitched every time) before my over enthusiasm tore the fly sheet one evening in Affric. Never convinced about the longevity of MSR (I have a Hubba).

1
In reply to ScraggyGoat:

Why would a tent floor have a HH rating? It's not like it needs to breathe or anything. It could be a sheet of rubber for all it matters. 

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 TobyA 04 Jun 2023
In reply to purplemonkeyelephant:

Hydrostatic head has nothing to do with breathability. It's purely a measure of how much weight of water the fabric can support without leakage as I understand it. 

 Damo 04 Jun 2023
In reply to UKC/UKH Gear:

"...for the groundsheet-protecting footprint."

You mean the floor. A groundsheet is a separate item, now often termed a 'footprint' (thanks America!). The bottom of the tent attached to the walls is the floor, as seen for years in the terminology 'bathtub floor' - never 'bathtub groundsheet'.

"...Macpac Minaret.... this robust and spacious tunnel..."

Robust yes, but spacious? I'm 199cm tall, granted, but can sit up in most tents without my head pushing up the ceiling (skysheet?) but not in my Minaret. It's low - part of why it's robust.

"...on my nepphews' Woodcraft camps."

Editing, ffs.

This looks like a cheap imitation of a Hilleberg, helped by giving it a Scandi-sounding name, which no other MSR tents have. As outdoor-goers get richer and Hillebergs have not increased as much as some other tents, they have become more popular and maybe MSR just want to offer up a match to that bit of the market.

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In reply to TobyA:

HH has everything to do with breathability. Qualities that contribute towards a high hydrostatic head will tend to make a fabric less breathable. Not linearly, but there is a correlation. 

A tent floor has no need to breathe, so engineering a tent floor fabric that has zero water permeability should be much simpler. 

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In reply to purplemonkeyelephant:

You can disagree with your dislikes but it doesn't change the simple physics that making something more resistant to water ingress makes it less able to pass water vapour. 

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 TobyA 05 Jun 2023
In reply to purplemonkeyelephant:

I haven't disliked any of your posts but I'm still pretty certain you are wrong. I do agree though that of course a groundsheet in a tent doesn't need to be breathable at all, and nor does the flysheet. So fabrics used are generally much cheaper than waterproof breathable fabric. That's why you can get decent enough tents that involve many square metres of fabric for a quarter of the price of a good goretex jacket that uses much less fabric.

 TobyA 05 Jun 2023
In reply to Damo:

Through my life going back to family camping holidays and Cubs 40 plus years ago I've always referred to the thing between you and the ground, whether sewn in or not, as a groundsheet of a tent. It's pretty normal in the UK. 

2
 crayefish 06 Jun 2023
In reply to Damo:

> This looks like a cheap imitation of a Hilleberg, helped by giving it a Scandi-sounding name, which no other MSR tents have. As outdoor-goers get richer and Hillebergs have not increased as much as some other tents, they have become more popular and maybe MSR just want to offer up a match to that bit of the mamarket.

On the money with that one.  This will never be a Hilleberg in terms of quality and sturdiness (there is a reason everyone takes Kerons to Antarctica) and the Scandi sounding name is a clear play to us Hille tunnel lovers.

That last part sounded dodgy... 

 mike123 06 Jun 2023
In reply to crayefish: wrt to a hildeburg I suppose it’s cheap but compared to many other very similar tents I think it’s expensive .  I ve got the alpkit version , at a casual glance I can’t see much difference . It was about £150 . I got it  for use with my kids and wanted something that I wasn’t too precious about  . It’s an excellent piece of kit which performs well above its what I thought was a very reasonable price . It was in a sale but these seem to occur regularly.

In reply to TobyA:

Why don't all waterproof membranes have high hydrostatic heads? If breathability has nothing to do with HH, surely all waterproof membranes would have high HH? It's not that difficult to make a fabric that's waterproof to high pressures if that's your only goal. 

2
 TobyA 06 Jun 2023
In reply to purplemonkeyelephant:

> Why don't all waterproof membranes have high hydrostatic heads? If breathability has nothing to do with HH, surely all waterproof membranes would have high HH?

Hang on - you are mixing ideas up here. Tent fabrics don't have membranes in the sense that Goretex or similar does. My understanding is that tent fabrics are single layers of nylon or polyester which once woven have a waterproof layer, polyurethane or similar, applied to it to make it waterproof - this is basically a layer of plastic 'painted' on to it. Uncoated nylon or similar synthetics isn't particular water resistant which is why you can make good windproof jackets out of them, but why, say a pertex top, is only a windproof not a waterproof.

On the other hand Wikipedia says "A membrane is a selective barrier; it allows some things to pass through but stops others." the goretex PTFE membrane so exactly that, it has holes in it big enough to let water vapour molecules through, but too small to let liquid water molecules through. The PU coating on a tent groundsheet I imagine has no holes in at all, but presumably with enough pressure on it I would imagine the woven strands of nylon are pushed apart enough to break the PU barrier and allow water through? But you'd need to check with a material scientist who knows more about the actual mechanical process of water getting through PU coated nylon. You see the PU flake off old nylon all the time through wear and flex - the inside of the spindrift collar on almost every rucksack I've ever owned being cases in point! So I'm sure the PU just wears away on tent groundsheets with use, so will eventually leak. 

> It's not that difficult to make a fabric that's waterproof to high pressures if that's your only goal. 

But for tents it's not going to be the only factor I guess. Weight, cost, durability, and I'm sure many others will all need balancing. Bin bags are completely waterproof and cost very little - why not use them to make tent ground sheets? Presumably because they rip and puncture very easily.

In reply to TobyA:

Fair enough, I had always assumed tent fabrics had a degree of breathability (even a cheap PU membrane would breathe) but from what I see fabrics like silnylon are not breathable. I guess its just specialist tents like the Rab Latok that use membranes. 

Hydrostatic head tests are supposed to force water pressure until water is seen on the other side. Perhaps someone may know - is that due to fabric failure (ie tearing) or is the fabric allowing water through the pores? (surely not possible?)

 galpinos 06 Jun 2023
In reply to purplemonkeyelephant:

> Hydrostatic head tests are supposed to force water pressure until water is seen on the other side. Perhaps someone may know - is that due to fabric failure (ie tearing) or is the fabric allowing water through the pores? (surely not possible?)

What pores are you talking about?

In the case of the Tindheim, it's made using a 68D taffeta polyester. Taffeta is a single weft/warp with a twisted thread. The water passes through the gaps between the threads?

 TobyA 06 Jun 2023
In reply to galpinos:

> In the case of the Tindheim, it's made using a 68D taffeta polyester. Taffeta is a single weft/warp with a twisted thread. The water passes through the gaps between the threads?

Although on the fly and groundsheet presumably the polyester is coated with PU or similar to make it waterproof?

 Toerag 07 Jun 2023
In reply to purplemonkeyelephant:

> Hydrostatic head tests are supposed to force water pressure until water is seen on the other side. Perhaps someone may know - is that due to fabric failure (ie tearing) or is the fabric allowing water through the pores? (surely not possible?)

It's through pores. Plastic is simply a load of strongly-bonded long chain molecules entangled together with weaker bonds. That's why they're flexible and stretchy. Consequently, it's possible for things like liquids and gases with small molecules to percolate through them, and the higher the pressure on one side (hydrostatic head) the more molecules are pushed through in a given time. Obviously the resistance to percolation depends on the plastic itself, and the thickness. If you have two groundsheets with PU coating it's possible for them to have different HH due to differing thickness, or differing PU constitution.  An extreme example is hydrogen percolating through metals - the hydrogen molecules are simply so small they can pass through the lattice of metal atoms. 

HH testing is discussed here:- https://www.sgs.com/en-gb/news/2019/12/the-background-to-rain-resistance-in...

  The problem for groundsheets, flys and waterproofs is that you invariably put the 'waterproof' layer on the inside to protect it from abrasion, but this allows the outer woven fabric to get wet and thus delamination eventually occurs.  Some materials put the waterproofing on both sides or the outside (think of the old Force 10 groundsheets of the 70s, Ortlieb bags & commercial fisherman's waterproofs which are PVC coated) to make them more waterproof, but at the expense of weight, packability and possibly cost.  It would be interesting to compare the weight of a groundsheet+footprint with the weight of a PVC groundsheet - would users actually be better off with the heavier groundsheet that they don't need a footprint for?

Post edited at 11:24
In reply to Toerag:

My understanding was that liquid water molecules were too big to fit through PTFE?

 TobyA 07 Jun 2023
In reply to purplemonkeyelephant:

> My understanding was that liquid water molecules were too big to fit through PTFE?


I think Toerag is talking about PU coatings which I believe is totally different way of waterproofing nylon compared to laminating a PTFE membrane to it.

In reply to TobyA:

But GTX also has a HH

 TobyA 08 Jun 2023
In reply to purplemonkeyelephant:

Sure - it's just a measure of water resistance, but again as I understand the mechanics (physics?) or how they keep water out and eventually let water in is quite different.

 jimtitt 08 Jun 2023
In reply to purplemonkeyelephant:

It does, around 28,000mm above which the pores in the membrane get stretched open enough to let water through. While it sounds ridiculously high when bombarded with raindrops at 100mph things look different!

 Ridge 08 Jun 2023
In reply to jimtitt:

> It does, around 28,000mm above which the pores in the membrane get stretched open enough to let water through. While it sounds ridiculously high when bombarded with raindrops at 100mph things look different!

28,000mm of water is about 275kPa of pressure.

I reckon (happy to be corrected) that equates to the dynamic pressure exerted by a raindrop travelling at around 24m/s (54mph)*

*Obviously a rain drop will splatter and rapidly decelerate when it hits fabric, reducing the pressure, but it's easy to see how heavy rain and driving wind will start to penetrate given time.

 Frank R. 09 Jun 2023
In reply to TobyA:

> the goretex PTFE membrane so exactly that, it has holes in it big enough to let water vapour molecules through, but too small to let liquid water molecules through.

That's not how their membranes work and a common misconception. The pores there are million times larger than a water molecule. There is no "liquid water molecule" or "water vapour molecule", that's utter nonsense.

The goretex membrane is hydrophobic, meaning any liquid water forms "droplets" on it, not passing through easily unless forced (that's the membrane's HH, which is just a convenient way of saying pressure).

Think molasses or honey on a fine tea sieve. It might not leak by itself, as it likes to stick together more than it likes to flow through the tiny sieve openings, but you can still force it through if you apply force (or heat it so it flows more easily – that's akin to water vapour passing through, but liquid water not as easily).

Of course, then it gets even more complicated, because most goretex membranes also have a thin solid polyurethane layer, but that's just for starters.

Post edited at 14:54
 TobyA 09 Jun 2023
In reply to Frank R.:

> The pores there are million times larger than a water molecule.

The Wikipedia gore tex article says "This membrane had about 9 billion pores per square inch (around 1.4 billion pores per square centimeter). Each pore is approximately 1⁄20,000 the size of a water droplet, making it impenetrable to liquid water while still allowing the more volatile water vapor molecules to pass through." I guess "volatile" here means they have more energy in them (warmth inside your jacket). But are you saying the size of water vapour molecules is still much bigger than the pores? So is a chemical process that moves them through the membrane rather than a physical one where they are just small enough to fit? 

> There is no "liquid water molecule" or "water vapour molecule", that's utter nonsense.

Fair enough, I think what I meant to say was a liquid water droplet. Actually when I wrote that I remember thinking - I'm not using the words right here am I because I guess one water molecule is one water molecule no matter whether it's solid in an ice fall, liquid in water or bouncing around more as a vapour.

I should add I've not studied any sciences since GCSE level many decades ago but I am genuinely interested in trying to get a clear idea of how the technology in our outdoor gear works!

 Siward 09 Jun 2023
In reply to Toerag:

> Some materials put the waterproofing on both sides or the outside (think of the old Force 10 groundsheets of the 70s, Ortlieb bags & commercial fisherman's waterproofs which are PVC coated) to make them more waterproof, but at the expense of weight, packability and possibly cost.  It would be interesting to compare the weight of a groundsheet+footprint with the weight of a PVC groundsheet - would users actually be better off with the heavier groundsheet that they don't need a footprint for?

Certainly proper force ten groundsheets were far superior to anything sold these days. Bar specialist backpacking tents I can't imagine why they are out of vogue. Footprints indeed!

 Frank R. 09 Jun 2023
In reply to TobyA:

> Fair enough, I think what I meant to say was a liquid water droplet. Actually when I wrote that I remember thinking - I'm not using the words right here am I because I guess one water molecule is one water molecule no matter whether it's solid in an ice fall, liquid in water or bouncing around more as a vapour.

It's confusing because Gore's marketing materials tended to be, well, quite 'simplified' from the physics perspective. I think it was their own marketing newspeak that talked about 'molecules' in the first place, which got parroted over by all the non‑scientific outdoor media since.

Yes, a single water molecule is obviously much smaller than any pore in the membrane – whether solid, bunging with others to make ice crystals, liquid, sloshing with others to make a droplet, or vapour, more freely and randomly moving around.

But in the liquid phase, water molecules somewhat more tend to "stick" to each other by intermolecular forces, forming droplets. It's the least energy state, basically. Think surface tension and perfectly circular droplets in zero gravity. Even a liquid surface has surface tension at the liquid‑air interface, that's how some insects are able to walk on water.

The membrane pores, much bigger than individual molecules, are water‑repelling. Think teflon pan or well‑oiled pan. That changes the contact angle and makes it easier for a "droplet" to form. Like in the honey example, the intermolecular forces are stronger, so the honey doesn't flow through the sieve. Or a tea leaf floating on the water surface, even if it normally sinks.

That internal adhesion or surface tension still keeps the liquid water, even if it's a liquid film composed of myriads of individual molecules and not just a few individual droplets, from penetrating the much bigger pores, until enough external pressure (HH) overcomes that.

Water vapour molecules are obviously much more energetic, being vapour. Like steam. Meaning they mill around more easily, alone, not sticking so much together, able to penetrate the much bigger holes in the membrane more easily.

If the holes in the membrane weren't hydrophobic, the much smaller water molecules would just wet them and flow through freely, like water on a sieve. It's the surface tension that prevents that. That's why microporous WPB membranes that are dirty with sweat and not washed enough can leak, like eVent or even Goretex. Think teflon‑coated very fine sieve versus a regular metal sieve. The former would hold the water longer, the latter would leak a lot.

It gets even more complicated because most microporous membranes like Goretex add a thin, solid, hydrophilic (water‑loving) layer. That's to protect the "sieve" from contamination from sweat, ruining its hydrophobic properties. Some do not, and have to be washed a bit more frequently. Obviously, the solid polyurethane doesn't have pores like the ePTFE does, but it can still transport water and vapour through capillary action.

Some other membranes use only this PU layer, without any micropores. Others still have hydrophobic micropores, but made from different polymers than PTFE.

Anyways, any WPB membrane needs some environmental gradient to work. Be it temperature differential, relative humidity, pressure or whatever.

Some work better in some conditions than others and vice versa.

Remember, there is no such thing as 100% waterproof. It's all about balancing the different forces, water can enter even solid rock under enough pressure, after all.

Tent coatings tend to be usually much thicker, so they are not really usually counted as WPB, being just a solid coating on the fibres. But with enough pressure, you can still force water through. Perhaps more easily, since the fibres in a typical woven fabric are much, much further apart than the pores in a microporous membrane. You could force water even through a "waterproof" plastic bag, given enough pressure (it would most probably burst first, of course)

But it's still enough for tent use, and not many people need a fully WPB tent, since that's a lot of £££ for a little benefit (the temperature gradient would be smaller, so it wouldn't even work that well at preventing condensation on the tent walls).

Apologies to any physicists and material scientists out here, as I have definitely made quite a lot of oversimplifications and mistakes, all in the interest of keeping it accessible...

Post edited at 20:35

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