Golite Ultra 20 and Nunatak Skaha Combo?

[Brad Rogers]

I recently purchased a Golite Ultra 20 quilt and am looking into replacing my Mont-Bell Alpine Down Jacket (which is a size too large anyways) with a hooded jacket for sleeping with while using the quilt. I have the opportunity to get a Skaha Plus (w/2oz overfill) for a good price (for a Nunatak) but just want to make sure it won’t be too warm.

I am hoping to be able to use the quilt down to the mid to lower teens with the Skaha and my Mont-Bell UL Down Pants. I am cold natured and a cold sleeper, but want to make sure the Skaha won’t bee too much. How would the Skaha Plus perform warmth wise to my current Mont-Bell Alpine?

[John Haley]

The fill weight is only a difference of 1 ounce. I would expect a difference of a bit less than 10F. I had considered a Skaha, but decided to go with a warmer PHD for really cold conditions. For lesser conditions I use a Montbell inner down parka.

[Richard Nisley]

Bradford

Assuming a good fit for both the MB Alpine and the Nunatak Skaha Plus (w/2 oz over fill) and a comparable insulation balaclava (Nunatak or Down Works) worn with the Alpine, the Nunatak would be ~4% warmer. Assuming you wore a light hat with the MB, the Nunatak would be ~12% warmer.

The Golite Ultra 20 is accurately ~28F Comfort rated. I used the accurate rating rather than the “Marketing Dept.” rating to determine the increase from the incremental insulation. Your Nunatak & MB pants, in combination with this quilt would be Comfort rated ~5F (assumes an R5 pad).

[Dan @ Durston Gear]

"The Golite Ultra 20 is accurately ~28F Comfort rated. I used the accurate rating rather than the “Marketing Dept.” rating to determine the increase from the incremental insulation. Your Nunatak & MB pants, in combination with this quilt would be Comfort rated ~5F (assumes an R5 pad)."

You're a genius. Care to calculate what the comfort rating would be for my warmest setup? I've got an Ultra 20, Montbell UL Down Inner Parka, Patagonia Capilene 2 polyester tee and some thin fleece pants (5oz) all sleeping on a NeoAir (R 2.6).

[Brad Rogers]

Thank you Richard! That lets me know what I need to know. I am just curious, as I haven't gotten a chance to really test the Golite Ultra 20 out yet, where the 28* comfort rating come from? Did you calculate the warmth, or did you find EN test results from the quilt?

[Jeff Patrick]

I second Dan's motion. Very similar set up here

[Richard Nisley]

Bradford,

I calculated it using thermal physics calculations. Inputs included an assumed base layer of .6 clo, assumed EN13537 standard pad, assumed sleeping posture, assumed metabolism of the average 30 year old male, published type of down in the quilt, published amount of down in the quilt, assumed body surface area covered, and an environment out of the wind.

[Brad Rogers]

Thanks Richard. I have learned a lot from your posts on this forum over the past few years. You are the insulation technical guru around here and you are certainly an asset to the lightweight backpacking community.

[Richard Nisley]

John,

Which PHD jacket do you own? Since you are an UL backpacker, I assume it is the Minimus. If so, please post your feed back relative to what type of temp range your jacket feels comfortable doing camp chores such as cooking a meal.

I hadn’t looked at the PHD product line until I read your post. I am impressed with the accuracy of their temperature rating and the breath of their product line.

[Diplomatic Mike]

Are you saying the PHD Minimus is warmer than the Skaha Plus, Richard? A friend has the PHD Mininus Pullover, and i have the hooded Skaha with one ounce extra fill. They aren't even in the same ballpark regarding warmth. My Skaha has about twice the loft of the Minimus pullover, and the extra warmth of the Skaha is noticeable instantly. The PHD Yukon looks pretty similar to the Skaha though.
Forgive me if i'm not reading your figures properly.

Where did you get figures for the amount of down used in the Minimus, Richard? I can't find it on their website. PHD don't usually say how much down they use in their lightweight stuff, despite emails requesting that info.

[jim jessop]

I've owned a PHD Minimus and agree with Mike. With less down and loft and with stitch-through construction it is not a good comparison with a Skaha and though a good piece of kit, it wouldn't be nearly as warm.

For lightest weight the Ultra Pullover

http://www.phdesigns.co.uk/product_info.php?products_id=240

and I'd get the optional hood, would be a PHD option but not as warm as a Skaha.

For comparable warmth the Yukon would be the closest, and it shares the baffle construction.

http://www.phdesigns.co.uk/product_info.php?products_id=240

Like Mike, I have previously requested the figures on down fill weight from PHD without success.

[Lynn Tramper]

Richard, are you saying that the baffled versus sewn through construction makes no difference to the warmth of the garment?

For the record, my partner has a PHD minimus and I have a Skaha hoody. I agree with the others that they are not even in the same league in warmth. The Skaha is seriously warmer.

"Like Mike, I have previously requested the figures on down fill weight from PHD without success."
Ditto. But Richard was comparing the MB to the Skaha, not the PHD. So we can assume that no one outside of PHD knows how much down really goes into their gear.

[Diplomatic Mike]

If you look at Richards table Lynn, he has the PHD Minimus down as having 5.5 ounces of down, and a higher clo value than the Skaha.

[John Haley]

Richard…
I have the Yukon Pullover (box quilted with 900 rated down), which obviously is in a much lower temperature range bracket (5F) than the others being considered. Being new, I haven't had the opportunity to use it in the situations I bought it for yet… mid winter around camp and for hammocking/ground dwelling with a Nunatak quilt when conditions get really wicked.

BTW, for anyone seeing the listed prices on the PHD gear, that includes VAT for the UK. The items actually end up less expensive than that price, even after shipping to the US. Additionally, they have a 10% off subsequent purchases. As with most custom gear company there is a delay since they have to make some of the items. Right now it's two weeks to a month before it reaches a customer in the US.

[Lynn Tramper]

Right Mike, that's what happens when you surf the web with your images disabled! So I wonder where he got that figure? Also, the Minimus pullover is listed at PHD as 300g.

[Richard Nisley]

Dan and Jeff,

The International Standards (IS) method for calculating a temperature rating for a bag or quilt is to standardize all of the variables other than the bag or quilt's insulation. The resultant thermal resistance measurement of the bag or quilt's insulation is then converted to the various temperature ratings such as LLimit (Comfort) and Extreme. The Comfort temperature rating means that the amount of heat generated is the same as the amount of heat lost. The Extreme temperature rating accounts for the heat capacity of the body. If the insulation of a bag or quilt is less than is needed, the body core slowly cools until shivering begins and sleep is no longer possible. The Extreme rating defines at what temperature this will happen after 6 hours. The heat generation source is a male human shaped instrument that generates the same heat output, in the same body zones, as the average 30 year old male. The test environment uses an R 4.84 sleeping pad and the dummy wears a set of long underwear, knee high socks, and a balaclava (.354 clo). The test environment is out of the wind and the humidity is kept near the mid point of saturation. My calculations assume the same IS standardization of variables.

The Ultra Quilt would test ~ 28F EN 13537 LLimit (Comfort). The following table will tell us what the revised comfort rating would be for modified insulation values you specified.

-Your Patagonia Cap 2 T and fleece pants = ~.6 clo and so this will add .6 – .354 = .246 clo.

-Your MB Down UL parka has an Iclo of 1.78. This insulation only covers ~50% of your BSA and there won't be a surface air layer in this application. This results in 1.78*.5 = .89 being added to the insulation value of the quilt.

[Dan @ Durston Gear]

Thanks a lot Richard. That is really interesting and useful info.

The sleeping pad sure makes a big difference, with the comfort rating jumping from 28F to 44F with the NeoAir instead of an R5 pad.

These type of calculations are really neat to think through. This will definately help my planning for some upcoming colder weather trips that I have planned.

Supplementing a closed cell sleeping pad under the NeoAir seems like a good way to start increasing the comfort rating of my sleep system.

[Jeff Patrick]

For those who use the Ridgerest like I do and have an otherwise similar set up, the graph still works as the ridgerest also has an r value of 2.6.

[Richard Nisley]

Mike, Jim, & Lynn,

With the standard 4.5 oz fill in the Skaha, the warmth comparison to the current Minimus version should be about the same when tested in a lab. Overfill in the Skaha is a completely different analysis. Hoods are options for both garments.

The standard Skaha will LOOK warmer because of its box construction but will test about the same on a thermal tester (no wind, lab environment). I base this statement on the large number of jackets I thermal tested last year. This range of products included both stitch-through and baffled construction. For the same fill amount, the difference in the insulation measurement was in the normal 5% error tolerance for being equal. At least in the range up to 6 ounces of fill, box versus stitch-thru construction averaged only about a 2.8% difference in the Iclo values. This is primarily attributable to the 2.8% surface area of the stitch through channels. In the range of the typical fill rates for down jackets, as you increase the down density (stitch-through), the conduction losses go up and the radiation losses go down to create a wash.

All of the red values in my table were calculated by me. I am well aware that they don't publish the fill amounts and this is an irritant to some. Neither Patagonia nor the North Face publishes their fill weights also. I reverse engineered the PHD Minimus specifications by analyzing their published fabric and garment weights to ascertain the down weight. I also reverse engineered their published Comfort temperature and activity description to ascertain the down weight. Both reverse-engineering-techniques yielded the same approximate value of 4.6 oz.

If either of you want to discuss PHD products further, lets start another thread because this thread now seams to be drifting off topic.

[Richard Nisley]

There was an error in my model used to calculate the the different temperatue ratings. I used the EN13537 Limit sleep position rather than the LLimit sleep position to compute the LLimit values. The prior post has been updated to reflect this correction.

[CW]

My experiences agree with Richard's chart almost dead on. I slept a bit chilled at 28-30 in an ultra 20 wearing my base layers plus a UL down inner jacket paird with a Cocoon Pro 90 balaclava on a neoair and I tend to sleep pretty warm.

[Richard Nisley]

Chris,

Thank you for the vote of credibility based on your personal testing!

[David Lutz]

Chris–just to confirm, that means you did not have a ccf pad? I have this exact set-up, including a 1/2" ccf pad and I am anxious to see how low it will go.

On a side note, how much overall effect would down booties have?

[CW]

Correct, I had no ccf pad under the neoair on the aforementioned trip.

[Richard Nisley]

David,

Your foot temperature would obviously increase significantly and reduce condensation in the foot of the quilt. The LLimit (Comfort) rating is based on the core temperature. I did the core calculations using down booties filled with 1 1/2 inches of 800 fill yielding an Iclo value of 3.83. As a result of adding the booties to the previously specified clothing ensemble, Rct increased by .27 resulting in a 2F difference in the LLimit (Comfort)F.

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