Sleeping mat help

[hobbitle]

Hi guys.

I'm considering a new mat system and would like your thoughts. I camp on snow in the winters and so want something that works for that with a Western Mountaineering -7 bag.

An Xtherm is definitely involved but I can't decide whether to use:

- Xtherm SHORT with rope or pack under feet/legs
- Xtherm SHORT with a half sized cc foam mat like the Gossamer Gear pads
- Xtherm regular
- Xtherm regular plus half size cc foam for redundancy

I dislike bulk and so am not the biggest fan of the cc foam idea but that said I'm also terrified of another mat deflating on me with no redundancy - I was lucky I wasn't on snow last weekend!!

What are your thoughts??

[Orion]

Slow leaks can be fiendishly difficult to locate. Try full water immersion with the pad pumped up and take your time looking on both sides. Keep in mind that it could be a seam or the valve. I had a pad once with a slow leak that I was never able locate despite numerous attempts. I finally gave up on it.

I don't think there's any magic about pads and punctures. The lighter they are and the more exposed to debris the more likely you'll get a leak sooner rather than later. Carry repair tape. If a total unrepairable failure could mean mayhem or death consider carrying a thin ensolite pad as a backup to use with your pack and any spare clothes.

Fortunately in the snow there tends to be less junk around to puncture a pad.

[hobbitle]

Thanks Orion. Yes I did do full water immersion and spent an hour looking for another leak - nothing. It is lasting much longer than before but definitely still deflating.

[GPSGuided]

Immersion + compression and observe.

[hobbitle]

Goodness me. Ok I edited original post to make it clear that I've already done that - twice and at length.

[Orion]

I don't know what else to suggest. I lived with my slowly leaking mat for a couple of years, blowing it up every 4 hours on trips. I tried soapy solution, immersion in hot water, over-inflation and immersion. I even built a container specifically for immersing the pad with heavy weights on top to try and force out the bubbles. Nothing, nada, zilch. I gave up. I don't know where it was leaking. It was maddening. Fortunately the retailer I purchased it from had a very generous return policy and I got full credit when I took it back after several years. But it really bugged me that I couldn't figure it out. It still bugs me.

Every pad I've owned has been punctured at some point and two of them developed leaks I couldn't fix.

[hobbitle]

Hey Orion, cheers, wow you really did go to great lengths to try and find your leaks! It really is maddening, I get all excited when I think it's fixed, it's GOT to be fixed because there's no bubbles or anything ANYWHERE - and it still deflates! Maddening for sure.

NB I've altered the original post to take the focus off the "how to find a leak" (which I am trying avenues for) and more on the "sleep system" question.

[GPSGuided]

Find it hard to believe that there's a significant leak but unable to find. Patience and meticulous technique required I guess., like many laboratory experiments. Frustration no doubt.

[South_Aussie_Hiker]

How are you inflating it Hobbite?

I thought my brand new All Seasons had a slow leak, would go down over three to four hours. I would wake in the night, and add more, then by the morning it was still a little saggy.

Started using the inflation sack instead. Also inflate it and let it sit as soon as I get into camp, rather than just before I go to bed. Then I top it off just before bed, and it has been perfect.

I assume my warm breath was making it feel correct, but then as the air inside cooled (happens slowly because it is so well insulated with the baffled chambers) it would feel like it slowly deflated.

It's just a random guess, but if you are inflating by mouth, try the inflation sack (filling it with cold rather than hot air), and allow it to sit (inflated) for a few hours before topping it up and then sleeping on it.

Completely solved my problem. Good luck either way!

[hobbitle]

Thanks SAH! Unfortunately I use an inflating sac thing It's always been fine until last weekend. Trying again in the bathtub today.

[FXST01]

Maybe it was an once off offence, maybe the cap was secured properly.

[South_Aussie_Hiker]

Okay, thought it was worth a try.

Good luck with the bath experiment.

Some people seem to find soapy water easier than trying submerge the whole pad in a bath.

http://outdoors.stackexchange.com/quest ... atable-pad

Once again... Good luck!

[GPSGuided]

It really is like running a lab experiment. Someone need to write a testing protocol. Good luck with the re-test, hope you'll find it this time. Also worth inflating and leave it overnight with a comparable weight and see. The valve issue could be interesting. With the cold and a bit of grit, they'll be stiffer and may not have been plugged properly.

[Supertramp]

Possibly put a black sheet under the mat when your checking for leaks in the bath, this should help make any tiny bubbles be easier to see.

[GPSGuided]

For a tiny leak, the sign may just be a bubble stuck on the surface of the mat than a stream of bubbles trough water.

[hobbitle]

For a tiny leak, the sign may just be a bubble stuck on the surface of the mat than a stream of bubbles trough water.

This is what happened!
I found it yesterday. The first couple of times it wasn't even making a tiny bubble because there was a bigger hole near it, and i think all the air was just streaming through the bigger one. I sealed up the bigger one but it was still deflating... another hour searching in a bath and the tiny hole was evident just by a tiny little bubble slowly forming on the surface and popping away, near the other one. Got the sucker!
Thanks for your help guys

[neilmny]

Is it a UL7?

[GPSGuided]

Congrats! Knew you can do it. Saved yourself $150 on a replacement.

[hobbitle]

Is it a UL7?

Yeah

[neilmny]

Is it a UL7?

Yeah

It's best to not fully inflate one of these mats. It helps to resist punctures a bit like lowering the pressure in a vehicle tyre when driving rough tracks. Just inflate it enough to hold your hip off the ground when laying on your side.
That's what i do with mine anyway and so far so good.

[hobbitle]

Is it a UL7?

Yeah

It's best to not fully inflate one of these mats.

Thank you for the tip - I will try this

[Orion]

Find it hard to believe that there's a significant leak but unable to find. Patience and meticulous technique required I guess., like many laboratory experiments. Frustration no doubt.

I would have loved to have had some better way to check for the leak. One problem is that you can't easily observe all the surfaces at once and press down on it with a weight. There are also bubbles that cling to the surface, depending on the material (my pad was a Thermarest Prolite Plus). I immersed it multiple times and looked carefully at different sections of the pad. There was nothing. I estimated that it was losing something on the order of 1 liter of air in 4 hours. That would translate into a stream of about 10 bubbles of 2mm diameter each second. How could I miss that? It seemed impossible and yet no bubbles were apparent even though it would lose this air if I left it sitting out overnight (or slept on it for about 4 hours).

I wondered if maybe it was leaking in some more diffuse manner. Could the whole pad have become permeable? Another thought was that immersion in water somehow plugged the hole. I never left it immersed for a full 4 hours to test that.

I had a similar small leak in a Neoair. Same thing, about 4 hours and it would "prompt" me to add air. I couldn't find the leak in the field but it was dead easy to find in the bathtub at home. It's a different material though.


Anyway, glad you found your leak hobbitle! :-)

[skibug]

Hey everyone!

I have had similar problems with slow leaks - they seem to take 4-6 hours to drop to half their volume, by which time you wake up with a sore hip and need to re-inflate. Sometimes you can find them with immersion, sometimes not. I have found with Big Agnes mats that they often leak around the valve - not a puncture, but a weakness where the fabric is glued to the valve unit, and delaminates creating a small channel. I use my mat a fair amount - 60 nights per year, they seem to start leaking around two years, or after 100 or so nights.

I would suggest that the amount of initial inflation is not a factor contributing to leaks - the high internal pressure will be caused mainly by you laying 50 to 100kg of weight on top, and will be much greater than any pressure created by oral inflation. Any one with some basic physics could probably expand on this further. Having said that, I agree that is not to good to over-inflate initially, because it makes the mat too hard to be comfortable - it needs to be slightly soft to have some "give".

Can anyone comment on Thermarest vs Big Agnes (and other brands) for durability/resistance to leakage? I've wondered if it's worth trying thermarest for its lighter weight and higher r value.

Thanks,

Skibug

[madmacca]

I would suggest that the amount of initial inflation is not a factor contributing to leaks - the high internal pressure will be caused mainly by you laying 50 to 100kg of weight on top, and will be much greater than any pressure created by oral inflation. Any one with some basic physics could probably expand on this further. Having said that, I agree that is not to good to over-inflate initially, because it makes the mat too hard to be comfortable - it needs to be slightly soft to have some "give".

Over inflation can cause problems when base camping (ie. where you are leaving your mat inflated during the day). A tent in full sun can get pretty hot, and if you inflated your mat hard in the cool of the evening, the internal pressure can get even higher with very warm temps during the day. I often suspect this when I see mats where the internal baffles and channels have gone. If you are leaving your tent set up during the day, it is a good idea to let a little air out in the morning - should take just a couple of pumps to get it back to original pressure in the evening.

[neilmny]

That's good advice madmacca.

[Orion]

I would suggest that the amount of initial inflation is not a factor contributing to leaks - the high internal pressure will be caused mainly by you laying 50 to 100kg of weight on top, and will be much greater than any pressure created by oral inflation. Any one with some basic physics could probably expand on this further.

In order to support your weight the internal pressure has to be at least equal to that produced by that weight. For a 100kg person and a pad with a 1 square meter bottom surface area that implies a pressure of about 1kPa.

If you try really hard you may be able to blow with a pressure of 15-20kPa. That's approximately the pressure that Cascade Designs warns you not to exceed in their pads (e.g. with a pump). When fully inflating a pad it's more likely that you'd achieve something more modest, maybe 5-10kPa.

Since the pad doesn't have significant rigidity and also can't expand very much once it's full, the total pressure is the sum of the initial inflation pressure and the pressure added by your weight. So if you only partially inflate the pad the total pressure may be close to what your weight produces. But if you blow it up firmly the inflation pressure will dominate.

Having said that, I agree that is not to good to over-inflate initially, because it makes the mat too hard to be comfortable - it needs to be slightly soft to have some "give".

I know that's the standard advice but I prefer my pad, including the NeoAir, to be inflated as firmly as possible.

[Orion]

Over inflation can cause problems when base camping (ie. where you are leaving your mat inflated during the day). A tent in full sun can get pretty hot, and if you inflated your mat hard in the cool of the evening, the internal pressure can get even higher with very warm temps during the day. I often suspect this when I see mats where the internal baffles and channels have gone. If you are leaving your tent set up during the day, it is a good idea to let a little air out in the morning - should take just a couple of pumps to get it back to original pressure in the evening.

I've always taken care to release some air from my pad when I'm leaving it set up for the day.

But I'm not sure it's really a problem. A temperature change of 40°C would only increase the pressure by 15%.

[madmacca]

Over inflation can cause problems when base camping (ie. where you are leaving your mat inflated during the day). A tent in full sun can get pretty hot, and if you inflated your mat hard in the cool of the evening, the internal pressure can get even higher with very warm temps during the day. I often suspect this when I see mats where the internal baffles and channels have gone. If you are leaving your tent set up during the day, it is a good idea to let a little air out in the morning - should take just a couple of pumps to get it back to original pressure in the evening.

I've always taken care to release some air from my pad when I'm leaving it set up for the day.

But I'm not sure it's really a problem. A temperature change of 40°C would only increase the pressure by 15%.

Yeah, the external seams are sealed pretty strong, and you're not going to burst it just from the temperature/pressure differential. But typically the internal channel seams and baffles aren't nearly as strong.

[Orion]

Yeah, the external seams are sealed pretty strong, and you're not going to burst it just from the temperature/pressure differential. But typically the internal channel seams and baffles aren't nearly as strong.

Cascade Designs says not to exceed a pressure of 3psi (about 20kPa). That's equivalent to a 2 meter column of water. They aren't just talking about burst pressure; it's a general warning. But it's very, very unlikely that you would be able to blow your pad up to within 15% of that pressure.

Maybe it's an issue as the pads age. It certainly doesn't hurt to play it safe and let out a little air.

[Moondog55]

I had the very devil of a time finding the tiny leak in my old Thermarest and the leaks in the MD basecamp pad are due to a porous coating and I got tired of taking the pads back for replacement so I just think I'll paint the whole thing with silicon
But the CCF pad is sort of mandatory IMO but even for UL it won't be a weight thing but as you say they are very bulky