WBRR - Which Pad

[Just Bill]

I have a REI AirRail that's 78 x 23 x 1.5". I'm wondering if the air rails will help with blocking the draft. With a R4.2 rating, I'm hoping it will add sufficient insulation down to 45*.

"Hybrid design combines an insulated-foam center panel with large air tubes outside to keep you from rolling off; outer tubes are insulated with PrimaLoft® microfiber fill"

You should be in pretty good shape on the rails.

It's the purely air filled cell designs that struggle in a hammock. With the Primaloft fill you'll see the same good results I see in the Exped pads (35* or so for mine)

The only concern is it looks like the foam inside is diamond cut vertically- as opposed to hollow core foams.
So you may not get as much pop out of the body as you would in other pads... but the backyard will be the only way to find out.

Sleeping pads are not designed for convection loss as that's not a factor when used on the ground.

A cheapie solution is to put a 1/8" Gossamer gear pad or similar solid CCF pad down first to help... but unfortunately simply looking at R value isn't enough. You have to consider the construction.
The Xtherm gets me to zero on the ground... 30* or so in the air.
An insulation filled chamber design generally sees little loss in performance...a down filled pad would perform as well or better than an Underquilt.

On something like that Exped I mentioned- you can literally feel the 20* or so difference from the synthetic filled chamber to the non-filled edges. So it's not a draft- it's that chamber itself with a roughly R1 value letting the cold by. It's like someone took a long skinny water bottle from the fridge and slipped it in your hammock at your thigh and shoulders in what is otherwise a warm system.

That's the biggest issue with hammocks (IMO) in the cold. If one small thing is broken... the whole thing is a bust.
On the ground you can usually roll over or shift to solve it. Even if I tried to side sleep on that pad and tuck the top quilt around me... the shape of the hammock compresses your top quilt and keeps you pressed against that uninsulated chamber in some fashion.

You won't have that with the air rail... but you may find the small gaps in the expanded foam on the main section of the pad bleed too much cold as the air moving below strips the heated air out of those chambers.

The other thing to keep in mind... it's rare the ground is much colder than freezing even when it's really cold out. So when it's zero... really your pad is only fighting about 20* or so. If there is snow... snow is an insulator so your pad has an even easier job. Wet ground is really the only tough thing (the dreaded 35 and raining). In the hammock though... your pad is not only dealing with the ambient air temp... but realistically the wind chill adjusted temp.

Besides comfort... I think one big reason pads get a bad rap for hanging is that it's very easy to overwhelm a standard three season pad in relatively mild temps.
That trusty NeoAir does the job for thousands of three season backpackers with no complaint... but put it in a hammock and it craps out as high as 55* and breezy.
Solid closed cell foam is not affected, but other those are not as popular and are by far the least comfortable pads in a hammock unless you trim/notch them or use a SPE.

[scrope]

Thanks for the detailed explanation @Just Bill. I wonder if using an under quilt protector to block the wind would eliminate that as a problem for pads and make them warmer in all seasons. An UQP isn't very expensive and can be extremely light for the amount of coverage it provides.

[dakotaross]

I used to have a RR that I also used primarily with a pad - that's the reason I bought one. I used the ultra warm Downmat 9, large size. My experience was that it sat a little high, putting my knees on the narrow ridge sides of the hammock when I was on my side. Lightening up on inflation only exaggerated the dip of my butt in the center of the hammock. And then, when used with light pads or with an UQ, I got some shoulder squeeze. So I just went back to GE hammocks.

If I were doing it again, which I'm curious about, I'd use a double layer of reflectix underneath a very light pad, something like a Klymit Inertia X with space to get some radiation reflected to you but away from condensation (which might be inevitable anyway). But that's a lot of bulk.

[dakotaross]

Thanks for the detailed explanation @Just Bill. I wonder if using an under quilt protector to block the wind would eliminate that as a problem for pads and make them warmer in all seasons. An UQP isn't very expensive and can be extremely light for the amount of coverage it provides.

"Eliminate" - no. Helps, yes, but IMO its not that much help. More so for quilts I think.

[BillyBob58]

Wow, a lot of data and maybe my mind is getting slower, but I am getting confused. I don't have a lot of pad/hammock experience, not counting the open cell foam(very compressible) pad of the HHSS. I have always used that HHSS, PeaPods and MWUQs, all quite successfully to at least their rated temps(except an JRB MW4 on a bridge, which I only managed to get to 10F, was toasty though, could have gone lower for sure).

My only real pad/hammock experience was stacking a Thermarest inflatable( 2.6R) UL 1" thick torso length on top of a 2.6R full length TR CCF RidgeRest classic. Held together with a Speer SPE with strips of Walmart blue pad in the wings. I was very toasty in a Speer hammock at 18F. (but I don't think wind was an issue) Other than that I have only added a torso length WM blue pad to my JRB bridge if I found myself getting chilly(using no under insulation for most of the night) a bit before dawn during late summer nights in the south, when cooler than normal. But that also worked great. So I don't have a ton of hammock/pad experience, but I am thinking more about it since I have started experimenting with a 90* Hammocktent.

I notice that MogollonMonster was recently plenty warm using a Downmat 9 in the pad pocket of a 90* Hammocktent at minus 3F. Does that sound right per folk's experience? But a long/wide weighs 44 oz, so a fair bit heavier than a zero rated full length UQ. And from what I am reading here, that pad would be warm to way below zero on the ground or snow, so it is still losing some warmth when being used in a hammock? IOW, it is rated to minus 36(R8), but no way in a hammock?

This business about the outer side tubes not being insulated sounds like a deal breaker, and I was not aware of it. But I am confused regarding exactly which pads are insulated in all tubes. Are the Downmats? The Synmats? would it be quicker to list the ones that are not fully insulated, or the ones that are? Or, maybe is this correct: it is only the hyperlight Downmat series that lack the insulation in some tubes?

Re: pads not being built to handle convection. I've already commented about the Downmat 9 apparently being fine to at least zero, assuming wind is adequately blocked. But are CCF pads any better when dealing with convection? Again, I was toasty at 18F(could have obviously gone a good bit lower) in a hammock by stacking pads not weighing much more than a zero F full length UQ, but I don't think there was much wind reaching me, if any. Would convection/wind chill have made a major difference with that CCF pad on the bottom?

But, the more I think of this, it seems to me wind chill would be an even bigger problem with UQs. No doubt, unblocked wind can make a zero rated UQ inadequate at 30F. I can't help but think it would be an even bigger dif with an UQ than a CCF pad. What with the UQ being way more breathable. A good breeze can blow the warmed air right out of a down filled chamber, and replace it with cold air. High enough wind can even compress that chamber. It would seem not so much with CCF. And again, are the inflatable pads more vulnerable to wind chill than the CCF? Any dif? Thoughts?

[BillyBob58]

I forgot to ask this: in the experience of you folks, how much does deflating an air pad- to make it more comfortable in a hammock- decrease the insulation of that pad? Is it directly proportional to the decease in thickness? I am using a Neo Air All Season 4.9R. I think it is 2.5" thick. If I only inflate it to about 1/2 normal thickness, should I expect the R value to drop to about 2.5?

[Just Bill]

Thanks for the detailed explanation @Just Bill. I wonder if using an under quilt protector to block the wind would eliminate that as a problem for pads and make them warmer in all seasons. An UQP isn't very expensive and can be extremely light for the amount of coverage it provides.

I'm and ultralight ground guy mainly in experience... so some hammock things don't always compute for me.

My understanding of an UQP is more for splash and underbrush protection... with some wind resistance being incidental really. Those are not really important when using a pad.


My UL mind tells me that I'd rather go with a few extra inches on each side of my tarp to cut wind or reduce splash... rather than carry another piece of gear and it's attendant weight.
Or simply go with my winter tarp that basically converts into a sock and can boost temps as well as sleeping in a tent.

My UL mind also suggests I'd be better supplementing with a GG thinlight pad (or section of it) to cut convection loss if needed. https://www.gossamergear.com/product...light-foam-pad

My UL mind also generally tells me that if I really want to push... the 16 ounce Neo Air Xtherm gets me around 20-30* depending on wind. In the midwest here we'd typically have some snow (or fallen leaves at minimum) which can be comfy enough that I can just take it to the ground if I get uncomfortable.

Keep in mind... we are talking bridges. Bridges are not the warmest things out there. A boon in the summer, but a problem in the winter. At some point for me it's not worth it to push too far.
The advantage to a bridge/pad combo is that you are ready to drop down on that one or two off night when things get brutal in an otherwise normal trip. Overall I find that a versatile combo on the AT or for a week long trip where I may want to use a shelter or sleep on a bald and stargaze.

If I'm going to a local group hang for two nights or less and expecting zero... I'll just bring a gathered end and wrap myself up in a double thick cocoon of down.

My bridges are very flat and wide... more like ground sleeping really. Even with a zero degree UQ I'm fairly exposed. Again- great in summer- but they sleep about 10* cooler overall easily if you don't button up your tarp into a sock.
I believe with the RR (and definitely with the JRB) you're much more 'in' the bridge and the UQ wraps you more so you get less heat loss up through the bridge itself.

[Just Bill]

Wow, a lot of data and maybe my mind is getting slower, but I am getting confused. I don't have a lot of pad/hammock experience, not counting the open cell foam(very compressible) pad of the HHSS. I have always used that HHSS, PeaPods and MWUQs, all quite successfully to at least their rated temps(except an JRB MW4 on a bridge, which I only managed to get to 10F, was toasty though, could have gone lower for sure).

My only real pad/hammock experience was stacking a Thermarest inflatable( 2.6R) UL 1" thick torso length on top of a 2.6R full length TR CCF RidgeRest classic. Held together with a Speer SPE with strips of Walmart blue pad in the wings. I was very toasty in a Speer hammock at 18F. (but I don't think wind was an issue) Other than that I have only added a torso length WM blue pad to my JRB bridge if I found myself getting chilly(using no under insulation for most of the night) a bit before dawn during late summer nights in the south, when cooler than normal. But that also worked great. So I don't have a ton of hammock/pad experience, but I am thinking more about it since I have started experimenting with a 90* Hammocktent.

I notice that MogollonMonster was recently plenty warm using a Downmat 9 in the pad pocket of a 90* Hammocktent at minus 3F. Does that sound right per folk's experience? But a long/wide weighs 44 oz, so a fair bit heavier than a zero rated full length UQ. And from what I am reading here, that pad would be warm to way below zero on the ground or snow, so it is still losing some warmth when being used in a hammock? IOW, it is rated to minus 36(R8), but no way in a hammock?

This business about the outer side tubes not being insulated sounds like a deal breaker, and I was not aware of it. But I am confused regarding exactly which pads are insulated in all tubes. Are the Downmats? The Synmats? would it be quicker to list the ones that are not fully insulated, or the ones that are? Or, maybe is this correct: it is only the hyperlight Downmat series that lack the insulation in some tubes?

Re: pads not being built to handle convection. I've already commented about the Downmat 9 apparently being fine to at least zero, assuming wind is adequately blocked. But are CCF pads any better when dealing with convection? Again, I was toasty at 18F(could have obviously gone a good bit lower) in a hammock by stacking pads not weighing much more than a zero F full length UQ, but I don't think there was much wind reaching me, if any. Would convection/wind chill have made a major difference with that CCF pad on the bottom?

But, the more I think of this, it seems to me wind chill would be an even bigger problem with UQs. No doubt, unblocked wind can make a zero rated UQ inadequate at 30F. I can't help but think it would be an even bigger dif with an UQ than a CCF pad. What with the UQ being way more breathable. A good breeze can blow the warmed air right out of a down filled chamber, and replace it with cold air. High enough wind can even compress that chamber. It would seem not so much with CCF. And again, are the inflatable pads more vulnerable to wind chill than the CCF? Any dif? Thoughts?

I'll try quick and dirty, lol. You and I tend to get tangled up.

Remember- all insulation is simply trapped air. The smaller the air pockets and the more air pockets... the better.

Down filled mat- basically an UQ really. That downmat 9 is 3.5" of down... suspended from compression inside the pad. In some ways it's BETTER than an UQ because you can't install it wrong, get a draft, or have any leaks.
3.5" of down is about -10* of down. Most zero degree UQ's sold by vendors here are 3" or more of down.

Synthetic filled mat- next best thing... however they are not filled to the brim like down mats are. In the case of the Hyperlight series by exped... the end chamber has zero insulation. But that isn't across the board.

Closed Cell foams- are basically the smallest air bubbles you can trap, millions of them, and they cannot move or shift.
Think of it like sealed glass windows... but with lots of panes. Other than the fact that it packs poorly and it requires a decent amount of it... it's probably ideal insulation to lay on (compress) because you can't compress it.

Open Cell foams- same idea... but the foam is air permeable. That's why it compresses better. Fine when suspended inside a pad that stops it from compressing... but not so good to just toss in and lay on as you will compress it.

A purely air pad- dead air is insulation. Much like the sealed pane window mentioned. In fact the difference between the neoair xlite and the xtherm is that one is a double pane (one air chamber) and the other is a triple pane (two pockets of air). That said; there is a reason that glass windows are not much more than 1/2" or so of dead air. The bigger the pocket of dead air the more micro currents form.

STILL AIR is a great insulator. MOVING AIR is convection and increases heat transfer. So a 3" thick sealed pane window would actually develop air movement within the chamber itself and reduce it's insulating value.
When the wind is blowing across the bottom of an Air pad, it increases the air movement within the pad itself and causes the pad to loose R value.

So that answers one of your questions... partially deflating an AIR pad... doesn't hurt and may even help.
However partially deflating a down mat much past 2/3 would reduce loft and potentially create a cold spot.

Because Closed Cell Foam is closed... it is not very vulnerable to convection loss and does make a decent barrier under an air pad. The issue is this gets a bit clunky... but it a very commonly used trick from the ground that also works in the air. On the ground you're fighting conduction. CCF does an effective job at 'breaking' that flow of heat loss in both scenarios.

On a pad like the Exped synthetic... the pad isn't filled like a downmat. The synthetic that's in there acts in a similar manner to a CCF layer. It breaks up the air movement within the mostly air filled chamber so you never develop a micro current of movement within the baffles. It keeps the air still by providing a thin layer of undisturbed or insulated air. It's a bit like closing a storm door over the regular door. The storm door has little if any R-value but it has enough to let the door itself do it's job. Again... that's why even half inflated these do well. So long as you don't bottom out to less than a half inch you have the same layers of still air working.

Besides simple convection losses from wind moving across the surface of your UQ... when it's really blowing it will magnify any minor leaks you may have.
As many here say... hammocks are pretty easy until it gets cold... then any little wisp of failure or weak point in your UQ fit is magnified.
Most of us have had that 'finger of frost' slip in some wrinkle of fabric or pucker of quilt.

Heat rises... so with an UQ you need to make sure you are trapping enough heat up top for it to warm the UQ itself too. In a gathered end you get a decent seal with the wrap up the sides and your UQ to complete the cocoon.
So long as your fit is good you're not leaking that small pillow of super warm air directly under the body fabric and before the UQ.
Cold air sinks... so when you do have a leak you have that pillow of air trying to rise out... and the cold outside air falling to take it's place if possible.

That's the issue with a bridge, especially mine. Since the profile is more like a floating cot... wherever your top quilt isn't overlapping the UQ you are providing an uninsulated spot for the warm air your UQ has trapped to escape.
In that sense.. a pad can do better in deeper cold as it covers the surface more fully. Even a small 1/4" air gap of hot air trapped between the underside of the bridge and the UQ has plenty of opportunity to work away from where the top quilt seals it to a portion of the bridge body that is uncovered and rise away. By the same token... any open area of bridge body provides an opening for cold air to sink into that pool of air.

I find that a bigger open quilt or even a down blanket occasionally serves me better in my bridges than a top quilt as it can insulate the full surface more fully. The problem with that is it's easier to 'spill' the blanket as I move around.
A fully sealed pod system would do the job... but greatly reduce the benefit of bridges... which is ease of motion and multiple sleep positions. It's not an impossible problem... but to me around 20* it gets to be a problem I'd rather not try to solve as there are lighter, easier, better options readily available IMO.

[dakotaross]

I forgot to ask this: in the experience of you folks, how much does deflating an air pad- to make it more comfortable in a hammock- decrease the insulation of that pad? Is it directly proportional to the decease in thickness? I am using a Neo Air All Season 4.9R. I think it is 2.5" thick. If I only inflate it to about 1/2 normal thickness, should I expect the R value to drop to about 2.5?

Using a deflated pad comes with variation in terms of how the pad deforms/compresses to accommodate your body weight, which is more a constant at full inflation. Lot of weight at the butt may compress more there and forces much of the air to the ends of the pad where it may be fully uncompressed. So, I think its nearly impossible to make a good correlation with some decrease in R value per % decrease in inflation. But then, R-ratings are dubious anyway.

I always heard about letting a little air out to make it more comfy in a hammock, but I think that's because most people were using regular length or longer pads where full inflation meant having a pad that would inevitably ride up the sides of the hammock. If you deflate a little to make it more flexible and you can situate it where you need to on your body instead of the unwieldy fully inflated pad dictating to you, end result being effective placement as directed by the user. I used a Big Agnes short pad that fit shoulders to calves. My head and feet would hang off the pad, exaggerating a flat lay, so I mostly went fully inflated as I just never had the same issues that others have with the longer pads.

[BillyBob58]

.........................

Keep in mind... we are talking bridges. Bridges are not the warmest things out there. A boon in the summer, but a problem in the winter. At some point for me it's not worth it to push too far.
The advantage to a bridge/pad combo is that you are ready to drop down on that one or two off night when things get brutal in an otherwise normal trip. Overall I find that a versatile combo on the AT or for a week long trip where I may want to use a shelter or sleep on a bald and stargaze.

If I'm going to a local group hang for two nights or less and expecting zero... I'll just bring a gathered end and wrap myself up in a double thick cocoon of down.

My bridges are very flat and wide... more like ground sleeping really. Even with a zero degree UQ I'm fairly exposed. Again- great in summer- but they sleep about 10* cooler overall easily if you don't button up your tarp into a sock.
I believe with the RR (and definitely with the JRB) you're much more 'in' the bridge and the UQ wraps you more so you get less heat loss up through the bridge itself.

That last sentence matches my experience, where I have found the JRB hammocks- used with the MWUQs, to be among my easiest hammocks to insulate. But I have never put the RR to the test, and if I do I don't yet have the UQ designed specifically for it, which might be advantageous to use.