Wanted: Practice on 20-30+m freehanging pitch

alastairgott

Well-known member
Bit of a random question, but I would like to practice on surveying a medium sized pitch (20-30+m) which I cannot touch the walls while I'm prussiking. The only complication is I want to use "modern methods" rather than the plumb bob method, so relies on the use of disto and PDA/android.


Had a few failures today, which was frustrating. So I want to iron them out before we go back.


That's why I want suggestions for pitches where you can't easily touch the wall from everyone, not just surveyors.


Don't mind where it is in the UK, I just want suggestions of a place that I can go which is good for the job of practicing.
 

Duncan Price

Active member
alastairgott said:
Bit of a random question, but I would like to practice on surveying a medium sized pitch (20-30+m) which I cannot touch the walls while I'm prussiking. The only complication is I want to use "modern methods" rather than the plumb bob method, so relies on the use of disto and PDA/android.


Had a few failures today, which was frustrating. So I want to iron them out before we go back.


That's why I want suggestions for pitches where you can't easily touch the wall from everyone, not just surveyors.


Don't mind where it is in the UK, I just want suggestions of a place that I can go which is good for the job of practicing.

The 25 m pitch in Home Close Hole.  I surveyed it several years ago.  I lowered a tape measure attached to a plastic coated diving weight.  It's a Y-hang and tight at the top but then bells out.  You are close but not touching one wall.  On the way out I stopped every 5 m and did splays as well as a shot down to the base station to define the shape of shaft*.  There's digging there in the upper series most Sunday afternoon and the team will be pleased to see you.  The pitch is currently rigged as we are working beyond S10 in Wigmore Swallet.  40 m of rope is more than enough to rig it.

* https://www.dropbox.com/s/871hz4seq936ruw/wighall2pitch.mp4?dl=0
 

JoW

Member
I'm not sure on the exact pitch lengths, and I'm sure there's more, but off the top of my head:
Yordas top entrance and the descent at the end of chapterhouse
Lancaster hole
Pool sink (3rd ish pitch)
Flood entrance main pitch
 

Alex

Well-known member
The Pikedaw Calamine Caverns Caverns has an ent pitch of 25m straight down the middle of the shaft. No wall touching there.
 

nearlywhite

Active member
mikem said:
Interesting that the only pitches offered so far are on Mendip...

As they have their amchairs at the ready...

Last pitch of North route Eldon?
To the rebelay in entrance shaft of rowter
2 of the pitches in maskhill
There's one most of the way up block hall.

Otherwise use a big arse pitch and just do 20-30m? Like the top end of leviathan before it bears the wall/ledge
 
Been pondering this myself, pitch surveys are never fully satisfactory with a disto and then Loch models look a bit rubbish.

I like Duncans idea and if I remember correctly from the Titan survey it looks like something similar was done there. Maybe RE could enlighten us as to how they did that.

The first entrance pitch in New Goyden has most of the problems you need, I have been meaning to go back and re-do that for a while, not 30m but very easy to get to. Come over and let's have a go.

Nick 
 

Andyj23UK

New member
to save you " running up and down teh country :

eldon hole ? - final pitch SW route or final pitch North route [ using the rebelay as a start point
 

Leclused

Active member
I presume accuracy of the compass is not that import. You only want to try-out work methods. So metal structures are perhaps an option too. So why don't you use an (abandoned) elevator shaft or an other tall (industrial) structure.
 

alastairgott

Well-known member
I guess, it's to try and work out a process.
At present, i'm woeful at best at surveying a pitch which is anything above 10m, (despite technical hitches which I wont go off topic to describe!)

Now I've prussiked up the pitch and therefore seen it for a second time (it's not a new pitch, so don't get excited!). I can see that I will struggle but will persevere.

I think what I may end up doing is surveying down the pitch, as there is a slope off the bottom which I think may make it easier than missing the top of the pitch and hitting the roof.
Also this will ensure I can get a tidy picture of the pitchhead.

What I'm thinking is two separate series' of shots:
1) a straight "plumb bob" type shot straight down the pitch to give the model a fair idea of the size
2) a series of shots connecting the start and end of the plumb bob using forward shots, back shots and continue here usage to get the splays of the pitch. This may work "ok" on the pitch I have in mind (3-5m from the wall), but would almost certainly not work for other larger pitches.

Process of thought for series of shots (2)

a) So I guess what I'm thinking is stand at the top of the pitch and pick my next point on the wall further down.
b) shoot a leg to that point on the wall
c) abseil level with that point, take a back shot so that i'm a survey station on the rope
d) immediately take the next shot to a point on the wall.
e) return the software to my point on the rope and continue to take measurements of the walls around me (splays).
f) abseil down level or below the point on the wall.




Having said that I really do like Duncan's technique.


I might have to try out both and see which I like/which is less faffy when your sopping wet. (most probably Duncan's now I think of it).
 

alastairgott

Well-known member
Thanks for all the suggestions, I've got plenty to practice on, I was also sent Sell Gill final pitch by an anonymous forum lurker  :beer:
 

damian

Active member
alastairgott said:
Thanks for all the suggestions, I've got plenty to practice on, I was also sent Sell Gill final pitch by an anonymous forum lurker  :beer:
Middle pitch, surely?
 

alastairgott

Well-known member
No idea i'm afraid, probably the pitch I once handed my handjammer to a person using ladder and lifeline so they could haul another group of unsuspecting "cave hunters" in trainers out.

i'll find it!
 

Rob

Well-known member
I also suggest Elizabeth in Nettle (mainly because there's currently quite a large error in the Crumble-Elizabeth round trip and i'm pretty sure it originates from Elizabeth  (y) ).

I don't understand why surveying a 20-30m pitch is hard with a DistoX. It's just another leg.

If you really want to split it up a bit (say, to add splay detail which can't be accessed from the top of bottom) then just make yourself a "floating" point in the middle.

Swallowneck said:
...I like Duncans idea and if I remember correctly from the Titan survey it looks like something similar was done there. Maybe RE could enlighten us as to how they did that....
Yes, Moose populated Titan with horizontal splays every 5m along a hanging tape.
 

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alastairgott

Well-known member
I guess it?s not, I?ve just had no practice. So before I go back I just need ideas to practice.


Otherwise I?ll be THE definition of insanity ;) : trying the same thing expecting a different result! :eek:
 
Frank Shaft in West Mine is pretty much bob-on 20 metres if you are at Alderley tonight, and can be set up to be free-hanging without touching the sides I think. It's got an optional bar about 2/3 of the way up for a re-belay if you want to make the surveying more interesting.

At the end of the entrance passage, turn right after the short ladder. Then go past the top of the next ladder into the low passage beyond. There's a bar across the passage just before the shaft top (which is just a hole in the floor).

The bottom part of the shaft just opens up into a medium sized chamber (a continuation of the main chamber) so you could do some splays to get the shape
 
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