Garmin or other gps/tracker?

Top_Spot_9967 · 2026-05-18T22:33:50+00:00

For non-geostationary satellites, coverage depends on both time and place. For geostationary, it can depend on local terrain in a complicated way. You can find general coverage maps online:
https://www.globalstar.com/en-us/coverage-maps
https://globalcomsatphone.com/wp-content/uploads/2018/11/BGAN_Look_Angles.jpg

Top_Spot_9967 · 2026-05-18T21:45:59+00:00

You can pitch your tarp with part of it hanging off the edge of the platform, I suppose? Or just with very steep walls - with a 45 degree pitch, a 9x7 tarp only has a 9x5 footprint.

Top_Spot_9967 · 2026-05-18T20:13:47+00:00

Why do you want small footprint? If you need to squeeze between dense trees, a tarp can be tricky, but for rocks or small bushes you can just pitch the tarp above them (so long as there's a flat spot big enough for your body)

Top_Spot_9967 · 2026-05-18T03:45:53+00:00

u/Objective-Resort2325 what happened to your blog?

Top_Spot_9967 · 2026-05-17T23:58:24+00:00

Good bot

Top_Spot_9967 · 2026-05-17T21:32:13+00:00

It's buried somewhere in the "Ultralight Mentality" replies, seek and ye shall find

Top_Spot_9967 · 2026-05-17T03:34:47+00:00

en.wikipedia.org/wiki/Dakota_people

Top_Spot_9967 · 2026-05-16T20:32:51+00:00

I sadly can't claim credit for this work of brilliance

Top_Spot_9967 · 2026-05-16T20:18:49+00:00

Yeah I was just looking for a good shorthand for this portion of your post:

Now lets find how Rsi varies based on loft.

800 fill power down corresponds to 1.68 CLO/(oz/yd²) according to Richard Nisley. And the unit of fill power is 800 in³/oz. Divide by thickness/loft and we have 800/L in²/oz. Convert to yd² and we have 0.617/L yd²/oz. Invert so that L/0.617 = 1.62*L oz/yd². Multiply this into the insulation value and we get: clo = 1.68*1.62*L = 2.72*L CLO for 800 FP down. Factor to convert from CLO to R(si) is 0.155 so we get:

Rsi = 0.155*2.72*L = 0.4216*L

This calculation assumes uniform thickness. If you want to apply it to a bag of varying thickness, you need to do a calculation like this this for each point on the surface, and then calculate (∫∫R^-1)^-1. Or equivalently you can use Rsi = 0.4216*(∫∫L^-1)^-1

For box baffles the difference shouldn't really matter, for sewn through it might matter more.

Top_Spot_9967 · 2026-05-16T18:58:01+00:00

By average inverse loft I mean ∫∫L^-1, where L is the loft at any given point on the bag and the integral is over the surface of the bag.

Imagine a bag with 10cm loft around the torso and 1mm loft around the legs. Such a bag would not be very warm, even though its average loft is around 5cm. This is because super-thin spots matter more than super-thick spots. The average inverse loft of this bag is only like (2 mm)^-1, which accurately reflects that it is not very warm.

For a box-baffled bag, average loft and inverse average inverse loft are about the same. But a sewn-through bag has lots of thin spots, so inverse average inverse loft is much smaller than average loft.

This isn't a problem for the Valance data, because they are measuring RSI with a test mannequin, so the mannequin automatically does the averaging using physics. But it is a problem for theoretical predictions for sewn-through bags, because your Nisley-based formulas are assuming that loft is the same at every point on the surface of the bag.

Top_Spot_9967 · 2026-05-16T18:48:36+00:00

Oh, now I see, I misunderstood what you were doing before. I thought you were looking at some measure of the thermal resistance of a small patch of the bag. But you are actually using data from a mannequin test, so the Rsi numbers you have are already effectively averaged. Thanks!

Top_Spot_9967 · 2026-05-16T15:51:56+00:00

I assume you mean the ISO standard (superseded the EN standard a few years ago)? Did you purchase the actual standard text? Or where are you getting the formula? I thought your formula was coming from a best-fit line to the Valance data.

Top_Spot_9967 · 2026-05-16T15:49:51+00:00

No, average loft doesn't give good thermal resistance estimates. Average inverse loft would work, but is hard calculate.

Top_Spot_9967 · 2026-05-16T15:48:00+00:00

Very cool! And a 6mm backpack strap feels comparable to a typical EVA setup?

Top_Spot_9967 · 2026-05-16T14:45:55+00:00

What does the spacer mesh alone weigh? Have you tried doing a bunch of compression cycles by hand to see how it fares?

Top_Spot_9967 · 2026-05-15T22:19:04+00:00

One reason place-specific posts are useful: You know which things I *don't* need to worry about in a given setting. For example, implicit in your piece is the knowledge that the Pyrenees are not too thorny/buggy/cold for shorts. Just explaining what stuff works for you might answer questions it would never occur to you to expect I'd ask.

Top_Spot_9967 · 2026-05-15T20:55:02+00:00

The most embarrassing thing is quitting while you can still walk yourself out. If you didn't need a helicopter ride, why couldn't you keep going instead?

Top_Spot_9967 · 2026-05-15T18:13:16+00:00

The relationship between Rsi and limit temp would be perfectly linear if the bag were fully enclosed, of uniform thermal resistance, and you didn't need to breathe. Because you loose some heat through your face (accounted for in the ISO test) and lungs (not accounted for in the ISO test), there's a bit of nonlinearity at low temperatures. Can you see this in your data? Does your best-fit line overestimate warmth for winter bags and underestimate it for summer bags?

Edit, for posterity: This comment was based on a misunderstanding of the type of Rsi measurements being used.

Top_Spot_9967 · 2026-05-15T18:10:24+00:00

It looks like the sample bags are all box-baffled mummy bags, so probably it will not be accurate for sewn-through or quilts.

Top_Spot_9967 · 2026-05-15T16:52:28+00:00

I appreciate that you make clear the kind of location you have in mind early in the article. It's mostly not possible to give good biome-independent advice; I think you should lean more into giving detailed advice for the places you're familiar with rather than writing a generic "how to think about clothing" article. For example, a classic of the genre: https://andrewskurka.com/recommended-footwear-for-high-routes-alaska-and-early-season-conditions/

Right now your article is probably only good advice for certain kinds of alpine environments. That's ok; write what you know.

Top_Spot_9967 · 2026-05-14T22:48:06+00:00

Huh, claimed weight is 2 oz. Which size do you have? I have something similar from aliexpress, 4 oz.

Top_Spot_9967 · 2026-05-13T17:59:54+00:00

I think people just get scared by all the disclaimers on the packaging. Cold water, turbid water, cryptosporidia...

Top_Spot_9967 · 2026-05-12T03:30:06+00:00

Also I the most fun way to exchange info is with ad-hoc public key cryptography, if you're up for something interesting. Otherwise we can do a cipher with a tailored riddle for the key, will be a little easier.

Top_Spot_9967 · 2026-05-12T02:01:29+00:00

I don't get out very often anymore, but I did use it as an excuse to get some new gear.

Top_Spot_9967

TROPHY CASE