I have read here, and it makes sense, that sleeping on a thick mattress on your bed at home will keep your back side comfortable regardless if you room temperature is 70* or 50*. Your "underneath" side will not overheat. If that being the case, all things being equal, and outside temperature stays constant all night, would not a 0* underquilt keep you just as comfortable as 40* UQ in a (lets say) 40* outside temperature? In other words, you cant over insulate... right?
Last edited by Crawldaddy; 09-26-2023 at 15:00.
I don’t know! You can test it yourself by comparing 40* and 20* under quilts on successive nights with similar temperature ranges.
Will it be too hot? I doubt it.
Someone last fall could have used a 20* under quilt but instead used a zero degree under quilt. I think temperatures got to mid thirties, and they said it wasn’t too hot.
For a low of 50, I use a 20* under quilt, leaving 40* under quilt at home.
I usually give a ten degree buffer for all quilts.
If a quilt is rated at 40* and forecast low is fifty, then I pack my 20* quilts.
EARLY in evening, if too warm, I push under quilt out from under hammock and let it hang alongside of hammock, while still attached. Then if getting cold during night, the under quilt can be pulled back under and around hammock without getting up out of hammock.
If I got paid to tell lies…it wouldn’t be as much fun
Ah GarnaUtees it!
Heat rises?
It's less true of hammocks than mattresses, because the hammock UQ wraps around you some. (That's true of bridge hammocks, too, but maybe not as much as GE.) The amount that an UQ breathes is a factor, too. That works in your favor, making a hammock with UQ comfortable over a wider range of temperatures than an air mattress. I like a warm UQ and achieve enough temperature regulation by adjusting my top quilt. Short answer: somewhat. By the way, what is this fictional place where the temperature stays constant all night?
I only have a 20* underquilt. I live in AL and rarely get that low, so I regulate with my top quilt choice or venting. If it gets too hot, I just move it over or loosen it a little. It's cheaper than getting a new quilt, though one day, I will.
I find I don't overheat from using too warm an underquilt even when the difference between the rating and actual temp is pretty drastic. For example, I won't overheat using a JRB Greylock 4 (0° 3/4 length) when the night temps are in the 60s. It seems to be a self regulating effect. The TQ on the other hand, if the temp is in the 60s and I have a 40° TQ I will wake up sweaty at times and have to vent it, kick a leg out, etc. Above freezing, I'm just sleeping in shorts and a T, most likely. I will get very hot quickly in too warm a TQ but I don't notice that effect at all with the UQ. If backpacking, bikepacking, or the like, the main downside to bringing too warm an underquilt is the added bulk.
Too many variables are involved. A thin reedy individual who weighs 93-lbs will need a vastly different insulation solution than a 320-lb individual who is not lean. Adding to that is wind, humidity, rain and metabolisms.
An individual with a BMI index of 19 and a low metabolism sleeping in 40-degrees F with 10% humidity will react differently when in 40-degrees F with 95% humidity and 25-mph winds.
Insulation only retains heat, and as mentioned, heat rises so, a highly windproof 0-degree F bottom layer that is evenly distributed (covers you downside with a good extra foot of coverage around your body, no matter how you lay will provide a good repeatable baseline.
The top insulation might be adjusted according to conditions at a 40-degree F level.
It all depends.
Last edited by joe_guilbeau; 09-27-2023 at 07:13.
Technically, no. Heat seeks cold. Warm air rises. And there definitely is a difference. (And, also, warm water usually rises. Leaving inversions out of the simple discussion of either medium.)Originally Posted by FLTurtle
cmc4free - I'm with you. For me, the UQ has an extremely wide range - as long as it is sufficient for the coldest temperature. The TQ, not so much. So a 20° UQ can be comfortable well into the 60° but a 20° TQ will overheat much sooner.
In order to see what few have seen, you must go where few have gone. And DO what few have done.
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