CTS 87.2291/g: NPC Journal 4(1), Jan 1987, pp 21-23

Upstream Gavel - Trimix diving

Rob Palmer

It seems that with each passing weekend, the possibilities of an Aygill to Kingsdale cave system grow closer. Many of the important links are close to falling into place, with a spurt of cave diving activity in the phreatic network beneath Leck, Casterton and Ireby Fells. How successful this activity will be is still open to some doubt; there are still gaps in the map that may take a great deal of effort to fill. The recent discoveries in Notts Pot fill in the biggest blank, and connections between Witches, Pippikin and downstream Gavel seem imminent, from one direction or another, joining the Easegill - Pippikin network to Lost Johns' - Gavel and giving the Welsh something to think about.

The next obvious link would appear to be with the Notts - Ireby system, via the new Notts downstream extensions and upstream Gavel. Here lies the enigma. Downstream Notts doesn't seem to want to go to upstream Gavel, having already bypassed it. Caves are where you find them, so the adage goes, and it is still possible that the cave might kink and head back for what has always been thought to be the obvious link. If it doesn't, then perhaps there's a whole new system behind upstream Gavel that we don't know about yet !

Certainly a lot more water comes in that way. My recent dives in upstream Gavel convinced me of that. The first was in September 1984, and was a bit embarassing. I'd never been down to the bottom of Gavel before, and arrived there with two 80 cu.ft. tanks and a 40, intending to stage through to the upstream airbell after 110m and push the deep pot found by Geoff Yeadon in 1974 on the 80's. Two lines led into this huge sump pool, and I assumed the obvious - one went downstream, the other up. Three attempts later, I realised they both went downstream, meeting a fair way in. Cold and disgruntled, I squeezed into the only other water surface in the chamber, a tiny pool beside the bottom of the pitch, and found the old upstream line tied off underwater. Pointing out to my shivering supporters from the Hades Caving Club that I might as well have a look now we'd come all this way, I got to the head of the shaft and down to a depth of -45m. There, a combination of cold, toothache and narcosis provided the excuse to return. Just as well, perhaps, as a concerned girlfriend had alerted Jack Pickup to the fact that we were a trifle overdue. We surfaced just in time to avert a full call-out.

October 1985, and ready to have another go. This time things were a little better organised, and Roo Walters, Mick McHale and Buckden OPC team got me and gear to the little pool again. This time I used a Unisuit, with two 94 cu.ft. tanks and a 30 full of oxygen to decompress on. The line to the airbell had broken 30m in, and I used some of my pushing line to reline to the 110m bell. There, the line to the head of the shaft had also broken, and the force of the water had lifted a 2 Kg lead weight up through the rift airbell, breaking the 6mm line it was tied to. This certainly proved the power of the stream coming up the shaft.

Fortunately, the end of the line to the shaft was still floating below the upstream side of the bell, so, trusting it would continue to float there despite the lack of belay, I swam on to the top of the pot. There I found it still bound securely round a large flake. Leaving the oxygen tank at -9m, I used the 25W lamp I carried to illuminate the shaft properly for the first time. The dimensions were suitably impressive, and I could tell that the line passed through a window at about -25m. Bits of organic material were being lifted up the shaft by a strong flow. The water was peat-stained, but clear. A valve change at -30m gave a moment of concern, as I breathed in nothing ! The tap had become turned off, but a quick twist of the wrist had air flowing freely again. I continued down, passing the -45m limit, and falling for what seemed an age. Finally, at -58m, Geoff Yeadon's old reel, rusty and corroded, hung suspended in the water. Two metres later, at -60m, I crunched satisfyingly down on a sloping gravel floor.

The only passage off lay downslope. It appeared that I was in the top of a large phreatic rift: almost, but not quite, filled by the gravel sediments. The force of the current was strong enough to maintain a narrow open passage, and I followed this down for what seemed about 3-4m, to where things got a bit constricted, though the passage still looked just passable straight ahead in the rift. I tied the line off to a large boulder back at the bottom of the shaft and headed up and out. Twenty minutes at 60m, at that altitude, meant a decompression of 45 minutes. The oxygen was used at -6 and -3 metres, and through the 110m sump for good measure. A certain sly pleasure was taken that evening in the Marton Arms, presenting Geoff with his old line reel. "That's Pooh's.", he said, "Now I'll be able to send it back to Australia !".

The dive still hadn't finished things, so on 30th December 1985, with NPC and Red Rose support, I went back again, in a short window between winter floods. I don't think I've ever had the privilege of such excellent support ! The original idea had been for Rob Parker to dive in and set an eighty cubic foot oxygen tank and line reel at the top of the shaft. I was then to stage in with an air-filled sixty, wearing two lightweight Acurex tanks, each filled with about ninety five cubic feet of Trimix, left over from the Wookey dives. Rob, however, had damaged his hand (the lad will abuse himself), and was unable to dive. This meant I had to carry the lot in one go, which in retrospect wasn't a good idea. It was difficult to get near the line in the 110m sump, and I lost it at least twice, ending up in a muddy alcove on the left hand side, about 50m in. There I stayed for a few minutes, waiting for the current to clear the water, before I realised I wasn't in the main flow. Sheepishly, I backed out until I was, and realised that the main passage had taken a sharp right-angled bend here, and I hadn't. To add to the problems, the valve on the stage tank had a medium-bad leak from the first stage, which worried me a bit. This meant I could use it only as far as the top of the shaft, and not to the base, as I'd intended.

Somehow, I got it all through the airbell, falling fully-laden into the water on the far side. Despite the high water conditions, the bell was still a sideways thrutch up halfway out of the water, along, and back down again. I had to wait a moment or two before my breathing slowed enough to put the valve back in my mouth. The Acurex tanks were so lightweight that I was a touch too buoyant. I would still have to take the heavier 60 stage tank down the shaft, just for the extra ballast. I arrived at the top of the shaft with the line looped round me. I'd have to worry about the few metres of passage back to the airbell on my return, but by now I felt quite sure of the geography of the place. The oxygen tank was tied on at -6m and, switching to Trimix, I purged air from my suit and went down into the brown void.

Trimix has a peculiar mixture of advantages and problems. The advantages are that it makes narcosis less of a problem (everyone gets narked below about 40m, its just more obvious at some times than at others), and makes deeper dives safer, to a point. The main disadvantage is that it encourages heat-loss. Helium is a thinner gas than nitrogen, and core-heat is lost on exhalation. I could feel myself cooling down, despite the Unisuit with its thinsulate underlayer.

The 60 was dumped on the gravel bank at -60m, and the new reel tied on. I felt much clearer headed than on the last attempt, narcosis had obviously had an effect, even though I'd felt fine at the time. The passage at the bottom of the shaft was longer than I remembered... I'd got 10m or so up it, a little more than the narcotic 3-4m I'd imagined. But the floods seemed to have changed the geography of the end. I'd been sure the way on was straight ahead, through a triangular opening at the very top of the rift. Now this seemed to be full of gravel, to the roof, and the way on was apparently a low and sloping "bedding" to the right, down a steep gravel slope. Perhaps the floods had shifted the banks around, or perhaps I'd not looked closely enough before. The passage was less than one third of a metre high, and about two metres wide. It sloped down at a little over 60°.

I tried to force myself into it backwards, feet first. I could feel the current welling up around me, and I managed to get about a metre and a half in. My chin was forced into the gravel, and it started sliding in around me. The gauge read -64m. Sod this, I thought.

I squirmed back up the slope, amidst cascading gravel, and ran away. Decompression took an age, but, on changing to oxygen at -6m, I actually felt that I was warming up. The Trimix had had me shivering at the lower stops. Regaining the airbell was a miserable experience, without the line, and with arms full of gear. Having the current to help me out was a relief, and I'd been back at base only five minutes or so before lights appeared at the top of the pitch. The dive had taken almost exactly three hours.

That was the last I saw of my gear before I reached the entrance. The lads on the support team were tremendous. One of the problems of deep diving and long decompression is that hard exercise immediately afterwards can still bring on "The Bends", even after the full decompression is satisfactorily done. This gave me the excuse for a very leisurely prusik back up the pitches, hiding (I hoped) the fact that my SRT is sadly rusty !

Icicles hung in the cave entrance, and the moor was covered in snow. Lights moved across the fell as I stepped over the shakehole stile and stumbled in their footsteps towards the cars. Don't let anyone ever fool you that cave diving is a solo sport. This one had taken a good team to create and we'd given the cave the best try we could. It had been a joy to be involved.

Perhaps the Notts stream will double back and go deep. A diver coming to the squeeze from upstream might be able to excavate a way through, if the vertical gap wasn't too great. But maybe another link will be found, and upstream Gavel will remain an enigma. In a way, I hope it does.


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