Leaving collapsed tarps or tents in the rain

If it's a tarp and you're in a forested area, just tie it off to trees…

or just don't use your poles for a day :)

Michael,

For me personally…I would end up packing my kit back up rather than leaving a shelter collapsed. With a nice light load I would even be tempted to bring it with me. I don't often stay in the same spot two nights in a row though so the decision is an easier one for me.

Either way I think the potential for damage is higher if the shelter is collapsed and that would be one of my driving factors in deciding to pack up rather than leave it.

If I came across a collapsed tent/tarp in the wilderness, I might believe it's been abandoned and take it with me.

A collapsed silnylon shelter would likely not do well in the rain. I'd think that water would pool and overwhelm it's waterproofness.

I'd just hike without poles. Or pack up my shelter. Or tie to trees.

I don't like leaving a shelter unless it is ready for any anticipated weather. An unsupported shelter doesn't fare well in wind and precipitation and anything left inside is equally compromised.

With my load so light these days, I rarely if ever leave my stuff. I am amazed at how many times I find the "perfect" campsite throughout the day and like having it all with me. When peak bagging I may leave my pack below – I have done that in the past – but for the past few years I even take it all with me to the top. It leaves flexibility to move on based on a better vantage point and I really like sleeping in a different spot each night.

Since my camera gear comprises most of my pack weight and goes with me everywhere (duh), there's not much reason to leave a camp behind any more.

It IS however motivation to lighten my camera load, which is quite a bit more expensive to accomplish than lighting my camping stuff.

When camping with a group, I leave mine collapsed with stakes in place and rocks on top, or I find a substitute stick(s). Nothing bad has ever happened.

If solo, I would take it with me.

A collapsed silnylon shelter would likely not do well in the rain. I'd think that water would pool and overwhelm it's waterproofness.

No.
I have left a piece of silnylon on my clothesline all day with several gallons of water in it , not a drop at the end of the day.

(note : there are water drops above water level from evaporation, but no leakage whatsoever)
Franco

Hi Franco

Your example suffers badly from facts.

The water pressure there is probably only 100 mm at the worst. I have never seen silnylon leak at that pressure.

Any faint water which did leak through the fabric would probably evaporate off the outer surface, leaving it dry.

Cheers

The water level in the center is about 25cm deep (the saddle on my bike is 28cm long)
but whatever…
Franco

Would Franco's example suffice to recreate the worst case scenario of water pooling on a collapsed shelter? If the water pressure in his example is ~100mm, I can't imaging pools of water on a shelter being even half that. Could they?

> If the water pressure in his example is ~100mm, I can't imaging pools of water on a
> shelter being even half that. Could they?

If the water's 25cm deep, then the water pressure (at least in the center) is more like 250mm (which should be elementary).

I challenge you to find a way to get rainwater to POOL water on a tarp that deep, whether it's pitched or not :)

Well, I don't believe that leaving a tent out, made of sil-nylon, is a good idea. Franco's example of it holding water is a good example why it makes a good tent. But, this basically relys on the water tension. The water tension is supported by the weave of the fabric. So, yes, it will suport a bubble of water. Likely much deeper than what Franco had in his tarp. But, if you place anything against it to interupt the water film, it will leak.

Another alternative for the trekking poles is to use a stick for day hiking and leave the poles holding the shelter.

" But, if you place anything against it to interupt the water film, it will leak."

You mean inside the tent?

I've pooled water an inch deep on WPB fabric, with paper towel inside, and it was waterproof for a while, but then it leaks a little, and then it quickly leaks a lot

Silnylon didn't leak after hours

But with a tent, there are seams, and it's possible the tent fabric is damaged. Leaving it collapsed with water pooling on it is a lot more difficult test than leaving it erect.

"Silnylon didn't leak after hours"
So, you are saying that they make good dry bags???? I don't think so. Unless they have some sort of other treatment, they leak when in contact with things like cloths or bedding.

" "Silnylon didn't leak after hours"
So, you are saying that they make good dry bags???? I don't think so. Unless they have some sort of other treatment, they leak when in contact with things like cloths or bedding."

In general I agree with you, but it depends on the silnylon. I had probably coated mine with diluted silicone. Then, it is totally waterproof and would make a good drybag (until the silicone started wearing off).

What you're saying is inconsistent with the hydrostatic head argument

In the hydrostatic head experiment, it's a short amount of time (?) and two drops in the test area are allowed

If you leave the puddled water on silnylon for hours with a wicking material on the inside it's a different experiment

"If you leave the puddled water on silnylon for hours with a wicking material on the inside it's a different experiment"

So a more realistic test would be to collapse the tarp over a pile of gear simulating what one might have underneath (bag, pad, pack, etc) and then turn on the sprinklers. I probably wouldn't go as far as leaving unprotected gear like that even on a trip. At the very least, I would stick everything in a dry sack if I couldn't watch over it.

Mike

"What you're saying is inconsistent with the hydrostatic head argument"
Not at all. Water tension is many times stronger than bonding between general water molecules.
When supported by a fine woven material, such as ripstop nylon (though Roger is correct in saying that the rip stop threads interupt the film leading to leaks) it is very strong. Soo, it will hold a LOT of hydrostatic head. Even water in a glass with NO support can easily reach 1 or two mm with no support. Support that film with a good hydrophobic material, in this case sil-nylon, and it becomes a good water bag. 25cm or more is easily possible. You would think that it is water proof. Not true. Add a hydrophilic material to the outside, such as a piece of clothing, and it looses it…it will wick through. It is not water proof. The hydrostatic head does not measure this. It only measures exactly what you described regardless of the mechanism. MSR's video for the "Fast Stash" is a bit misleading, unless they are still using the PU coating as on the Thing"… Bad for condensation, good for water resistance.

The argument is that if the hydrostatic head is greater than some number, like 100mm, then the fabric won't leak.

What you're saying is inconsistent with this – if there's a wicking material on the inside, it will leak.

The wicking material against the fabric on the inside totally changes the experiment.

Yes, of course, it is a different experiment, obviously. One side is water and pressure. The interface is the material to be tested. A second layer invalidates the experiment, of course.

I've left the collapsed tent (still tied to the stakes) with rocks or small logs on top. I try to arrange the tent so there won't be any puddling. However, i've never had to test this setup in a hard rain, just mild drizzle.

Obviously, no food or smellables are left in the tent while I'm away from camp. Also, I wouldn't do this unless stealth-camped well away from the trail or popular camping areas.

The stick is a possibility–the one time I tried it, though, it took almost 2 hours to find one the right length! I do have a carbon fiber tent pole that I sometimes take along if I'm going to be base camping and doing mostly day hiking.

Hey Franco, don't let the staff beat you down. That is a practical way to show that pooling water isn't going to leak in unless the HH is bad. And if you touch it it still does not leak through!!! You show it resisting 300mm of HH or so. I HAVE seen Silnylon leak with as little as 100mm of HH and it's drips right on through – no way it's going to evaporate quickly enough. Bad silnylon is a big reason people are talking about HH. Much of the silnylon on the market probably can't hold a cup of water – it's no wonder there is a misting problem.

Hi James

> Add a hydrophilic material to the outside, such as a piece of clothing, and it looses it…it will wick through.
Sorry, but I am going to have to disagree with you here.

If the fabric has a membrane (like silnylon, then putting another bit of fabric on the underside will not, in my experience, cause any change in behaviour. The membrane does not rely on what is in contact with it: it is the membrane itself which is blocking the water. Silnylon (for instance) leaks when the water pressure on the wet side is high enough to open a pore between threads. This is what the hydrostatic test measures.

If the fabric does not have a membrane but is relying on surface tension to block the water, then under some conditions putting another fabric against it might, sometimes, allow water to breach that surface tension layer and for the primary fabric to leak. EPIC tents are very prone to this problem. It's very different from a membrane fabric.

Cheers