John Muir Trail Record Attempt 22-July

^^^^

"Spot reception is funny."

Yep. Hard to figure out how it can be off by so much.

Edit: This view is towards the southeast.

There is a strange part of GPS reception. It is called a GPS blunder. It tends to happen more with small scale receivers using a basic GPS antenna. It can happen anyplace, but it used to happen more when there were fewer GPS satellites visible. I used to see a blunder once per year or so.

When a GPS receiver makes a PVT calculation (maybe once per second or more often), there are typically two possible solutions. The receiver uses heuristics to determine which of the two is more likely, and that is what it furnishes as the result. Typically, the incorrect solution is extremely unlikely, like if you were moving very rapidly a hundred miles away at an unlikely altitude. The correct solution is typically somewhere within 100-300 miles from your last position. Nearly always, it gets it right. Once in a while, it gets it wrong. If you are monitoring the result very closely, you will see this false result. Then if you shut the receiver down and start it up again, it will purge the false result and come up with the correct result. With something like a Spot device, the user isn't monitoring the result, so a blunder can exist for a short period of time until the satellite constellation shifts around slightly, and then it disappears.

You will see this virtually never in a Mil-Spec GPS receiver.

My old GPS receiver once showed me about forty miles away, at high elevation, and traveling 500 mph or so. I saw it, shut the receiver down, and restarted it. Then it showed me backing my car out of the garage, which was correct.

–B.G.–

"There is a strange part of GPS reception. It is called a GPS blunder."

So in this case there were 4 consecutive "blunders" – 6:48, 6:54, 7:04 and 7:14 ?

(at 7:24 SPOT was back on the JMT)

Greg, isn't that sort of the same thing that happened near the Charlotte Lake trail junction on the first night? The original track showed it way off the trail. Then it seemed to mysteriously auto-correct.

I was somehow thinking that the earlier set of Spot tracking points were at ten minute intervals on the eighth minute. Then all of a sudden, they are on the fourth minute. That suggests that something like a restart happened within the Spot device. I don't know whether that was by user intervention, or by the device itself, or by magic.

–B.G.–

I have Garmin 60CSx. It occasionally "gets lost", for example:

I was going up the road. Suddenly got off by about 0.3 mile, paralleled the correct route, then "it figured out it was wrong" and gradually got back to correct route.

I also have the correct track on the way back so you can see what correct is.

"Spot tracking points were at ten minute intervals on the eighth minute. Then all of a sudden, they are on the fourth minute. "

Interesting. Same thing occurred here. 8th minute , then 4th on the north shore.

Minor Restart, and iterate to actual?

"Minor Restart, and iterate to actual?"

Different GPS receivers operate differently. Some have logic that tells them when the satellite signals are getting too unpredictable to use, so they shut down and start all over with a new almanac and new ephemeris table. Some will restart when the ephemeris table is too old so that it can acquire a new one after the restart.

I've spent a great deal of my life studying GPS records to look for trends in the hopes of determining what the hell is really going on. However, really good GPS receivers furnish a lot more information than what we are seeing here.

Just think about it. This thing is making calculations with Nanoseconds.

–B.G.–

Well, regardless of the clock rate, it has now been stalled for over 3 hours.

Low battery?

Does the user have to change out batteries periodically?

–B.G.–

Edit:

The last point at 11:30 PT showed a GOOD battery state.

at 11:30 she had ~ 12 miles to go, maybe 6 hours ?

SPOT should show up again, I would hope.

somebody posted on facebook an hour ago that she finished

https://www.facebook.com/pages/Jenn-Shelton/230834343628082

https://www.facebook.com/pages/Jenn-Shelton/230834343628082#!/ScottJurek?hc_location=stream

Scott Jurek said July 24 "Last minute trip to the Sierras for some surprise "trail magic" for Krissy Moehl and Jenn Shelton on their 223 mile John Muir Trail record attempt!

Dusk last night at Long Lake, Bishop Pass Trail 10,700'" picture of Long Lake

and yesterday "Found a spunky and solo Jenn Shelton outside of Reds Meadow, Krissy Moehl stopped near Edison Lake. Continuing on to Tuolomne with her now, she's getting it done this time!"

assuming he posted with cell phone – says cell phone is more reliable than SPOT : )

Erik Skaggs ‏@theskaggs

“@SheltonJenn finished the JMT at 4:36 this afternoon.”

By my unofficial, hasty, SPOT/Local/PCT time calculation –
(start: Whitney Portal – 7:11 am on 7/22 ….. finish: -“the sign”? 4:36 pm 7/26)

~ 4 days, 9 hours, 25 minutes

Way To Go!

record is 84:12

that would mean she did 105:25

is the record from Whitney Portal or Whitney?

anyway, didn't beat the record but still amazing

Hopefully they'll write-up some details about this. Would make a good story. I like the part about Scott joining up which I assume was unsollicited if he called it "trail magic".

Darcy Africa started an attempt at the women's unsupported record this morning after drawing a walk-in permit at the NFS office in Lone Pine. She has a SPOT, but I do not know if she intended for that to be public. For whatever reason the first SPOT point is at about Trail Camp, so I do not know her exact start time. She did tell me that she planned to announce the attempt publicly, but I don't see that she did. At this moment she is just about at the summit of Whitney. The FKT is currently held by Michelle Jung, who did 6d11h35m last year from Whitney Portal to Happy Isles.

GO DARCY!

This seems pretty close after her Hardrock win for Darcy to be going for such a grueling effort, but I guess she knows what she is doing.

Doesn't she go by Darcy Piceu now ?

Darcy made it to the Charlotte Lake jct last night – around 43.5 miles. Not bad considering a late morning start after dealing with the permit office. She got a pre-dawn start & is about at the Woods Creek bridge now – 53.5 in very roughly 24 hours.

Yeah, I'm going to have to remember to call her Piceu again! GO DARCY!

(ps. I won't be able to keep updating as I am departing on my own adventure this afternoon.)

I got to Tuolumne last year (120 was closed to Yosemite from the fire) in 6 days and 6 hours.

That was spending 19 hours at Reds Meadow and getting 6 1/2 hours sleep the next.
I had to slow down in order for my wife to pick me up at the pre-arranged time that was going to be Yosemite and was now Tuolumne.

I started with 17.5 pounds and just bought an apple and a candy bar at Reds.
Could have easily gone to Yosemite on what I had.

So I'm just saying that someone like Darcy should blow the female unsupported time away.

My day were slept at the following locations and she's already way ahead of that pace.

Night 1 – Just before Vidette Meadow
Night 2 – Half mile after the low point of the trail between Pinchot and Mather
Night 3 – Evolution Lake
Night 4 – Just after Edison Lake
Night 5 – Reds
Night 6 – Seven miles prior to Tuolumne.

Darcy is going to kill it.

Very impressive by Jenn! I hope she shares more details about her attempt and what some of the hurdles were.

I really appreciate them sharing the SPOT track! It made this into something of a spectator sport. I was hooked for a few days!

As an aside–from her SPOT track, it appears Jenn deviated from the JMT near Tuolumne meadows, staying south of 120, shaving something like 0.5 miles off the distance. I realize that I have no idea what her intentions were at that point, but I'm curious as to whether or not something like that would DQ a FKT attempt.

Lastly, I think this solidifies in my mind how amazing Ralph Burgess' recent FKT SoBo effort was! He is not a sponsored ultra-runner, and he is 50 years "young"! He only took a few hours longer than Jenn going SoBo. Ralph (or someone else) may have said this, but maybe 200+ miles is where the tortoise starts beating the hare?

No disrespect or disdain meant towards any of the athletes mentioned in this thread–they're all amazing! Kudos to all of them for getting out and doing hard things, and kudos to all of them for sharing!

Hey Adam,

Every attempt since (I think Brian Robinson) has gone bellow HWY 120.
The new maps even routes you this way. It's just the signs that have not changed.

As of now, we can say, the JMT goes 223 miles without crossing a road.
Or we can walk through 2 parking lots that the trail ends into and starts up the other side.

Its my understanding that for some years now the Park calls the routing south of HWY 120 the Official JMT route. This is because Tuolumne Meadows where the Classic Route runs thru north of 120 is a very fragile area and they are trying to keep traffic and environmental damage to a minimum.
So if Ralph Burgess did the classic route he hiked about a half mile more than every one else.

… and now I'm hearing from another thread that the entire Sierra from Bishop to Yose is filled with smoke.
hope this does not affect Darcy's speed effort.

These two came running past my camp towards the end of my JMT SOBO.

I have nothing else to add to this, just thought it was cool to run across them (no pun intended).

"maybe 200+ miles is where the tortoise starts beating the hare?"

It does seem that until Brett Maune's run, no elite athlete had really put up a "respectable" marker – in other words, a time that was in keeping with their raw cardiovascular/metabolic capacity. Even with Michael Popov's prior record, for example, I think we can now say for sure that if he had "got everything right" in the execution, there's no doubt that somebody of his immense ability could have gone much faster.

Now, I do think with the record where it now stands, comparing Jenn's time to mine doesn't really hold up – because if she'd been targeting MY time, she would have started much slower and no doubt totally demolished it. But Jenn was targeting a time that's a full day quicker than mine – going much faster than me in the first half – so if you slightly misjudge the effort and blow before the end, your average speed will collapse of course (and with the record beyond reach, there's little point totally burying yourself). So it makes me look good (!), but it's really not a valid comparison. More logically, Brett's time is representative of an elite athlete, and mine about a day slower seems reasonable to me, given how much quicker he is over shorter distances.

Having said that, it does seem that things frequently go badly wrong for elite athletes attempting this, with an unusually high failure rate – stories of hallucinations, major problems with food, hydration, electrolytes etc. On the hypothesis that it's sleep deprivation that's a big component, I do wonder if a much more structured approach might work better at >200 miles? My impression from having now read trip reports from some of the elite runs is that they were quite unstructured – in some cases seeming almost chaotic – grabbing a bit of sleep here and there almost at whim, also not eating steadily. My hike was done more as an extension of regular backpacking "hike during the day, sleep at night" – ok, my "day" was 18 or 19 hours, but I got one decent chunk of sleep in each 24 hour period. I also ate a lot, and ate very steadily, and had no major problems processing almost 6000 calories per day. As for rest – frequent short stops are probably better physiologically, but I was definitely getting at least a limited amount of REM sleep, and I didn't have any sleep deprivation symptoms beyond mild light headedness.

In anecdotal support of this… I notice that Brett (accidentally!) had a pretty long sleep after his first "period of consciousness". I wonder if that actually worked out in his favor?

So… I'm wondering if the right sleep strategy to beat Brett's record might be
first 24 hours: run ~60 miles at ~3mph, possibly eating more than usual for ultradistance, then sleep 4 hours
second 24 hours: run ~60 miles at ~3mph, sleep 4 hours
At this point, with a reasonable amount of REM sleep, it may be possible to just push on through to the end on the easier terrain without sleep deprivation taking you out.

(I say "Brett's" record only because for subjective aesthetic reasons I'm more interested in unsupported runs; but sleep considerations are presumably not much different for a supported attempt. There's only so much a crew or pacer can do to keep you pointed the right way on the trail if you're hallucinating!)