Wednesday, September 10th, 2014 at 2:28 pm - Kayak Dive
We went away for some kayak diving in Pembrokeshire over the weekend. I wanted to dive on the north coast from St David’s, but the north wind had picked up, so we directed ourselves to the south coast and going out of Solva after camping on Friday night in a layby to the east of Felindre Farchog on the A487 that had bogs. A useful discovery after drawing a blank going down some of the single-track back roads near there at one in the morning.
There’s not much to report on the diving. No amazing sights. Not a conger eel, or dolphin, or trigger fish, or even a spider crab. It was mostly kelp, gravel, silt, and a few pollacks. Everything had gone away for the winter even though the water was as warm as it is at any time of the year. The energy for life comes from the sunlight, not from heat. The cliffs were empty of birds who had abandoned their ledges that they had spent the spring and summer painting white with guano.
Solva harbour is pretty dry most of the time. After waiting 5 hours for the tide to rise, we dragged our boats out when it was at this level.
Becka is unimpressed by this strap coming loose on to which she had tied her canoe for this dive on the south side of Green Scar. There were gusts of wind on all sides of the island, even on this seaward side which was supposed to be sheltered. We did a shallow short dive, then got back on the boats and paddled into the wind to get back to the coast. There had been a slight concern we weren’t going to make it after going off-shore like this, but there wasn’t a problem.
We camped at Cairfai Farm, the low-carbon tents-only campsite south of St David’s on the coast, having left our kayaks on the beach so that we only had to carry the empty tanks up the steps to change them at the car.
My old set of electronic charts are broken, but after looking at a chart of Ramsey Sound on the wall of a pub I spotted a wreck in Porthlysgi Bay which I could look up accurately on the internet, which meant we could dive the wreck of the St George the next day.
I don’t know anything about it, except there were a lot of tall bits of metal which Becka had to thread the kayak anchor line around.
After this, the options were to either drift round on the current into Ramsey Sound, or go back along the coast for a final dive off the east side of Porth Clais where there was a deep section of sea bed close in shore, according to the charts (about 13m).
Being chickens, we opted for the latter. I’d also told the coast guard we’d be off the water by 6pm, so there wasn’t much time left. I always inform them now after getting call-outs due to walkers who see us fall in the water and start thrashing around trying to get our kit on before appearing to drown.
It was a long drive home via the chip shop in Fishguard. I still need to come back and do that north coast again when it’s in shelter.
Friday, September 5th, 2014 at 12:56 pm - Hang-glide
I got a lot of other more important things I should be blogging about, but what the heck. This is a quick one and I want to relive it. I got out yesterday for a flight on Whernside and persuaded a caver to carry up my harness for me and make sure there wasn’t a crash on take-off because, as usual, I was pretty much alone again.
A paraglider did walk up just as I was ready to take-off. Unfortunately he didn’t join me in the air for very long after he launched half-way down the face of the hill to avoid the wind-speed.
This is the fifth time I’ve carried my glider up this hill. It’s doesn’t feel very far now.
Classic British method of rigging with the glider flat on the ground.
The air was very murky, but actually blowing on the hill properly for a change. I got up high 400-500m above take off three times.
This is about 8 minutes later after I lost my altitude and was now below the ridge again. I don’t have enough experience to tell whether this was my fault through incompetence, or whether it was unavoidable. That’s one reason to have other people in the air.
I had to pack up early, and flew straight out from the ridge against the wind to land just the other side of Low Sleights Road by Ribblehead, which was not bad going. I cannot get over just how barren and bleak this landscape is.
Is it all because of the sheep, because otherwise it would be a total forest — as it is inside any enclosure?
I did get a very short canyon trip with an even shorter rope before expo was finished.
The canyon was called Salza Stauseeabfluss, and it went from the dam on the lake from Grimming. The rope was labeled at 80m, but no one had noticed it had been cut at 36m when they picked it up. We had to descend down the wall of the canyon in three stages off trees. We also got the walk out spectacularly wrong, and ended up clawing our way up a 60degree grassy slope in the dark.
This was on the same day I had a very nice 3 hour flight off Loser totally alone (due to west wind predicted) with a relatively low cloud base again, and tactically squeaked through the pass into the Bad Mitterndorf valley knowing that there was a good landing field there which I had used a week earlier.
Unfortunately every single field including this one seemed to be full of tractors cutting and bailing hay. Fortunately, a bird appeared and showed the way up to the clouds after 15 minutes of barely maintaining height.
That’s one of the lessons from the 50k Or Bust Book: both time and place matters. Use your arithmetic to know that a slow descent rate of 0.2m/s is only 12m a minute (or 120m in ten minutes), which means you can stay in the game for long enough for the next thermal to rise.
Because the clouds were low, I didn’t want to stray up into the mountains, and stayed close to the valley where the lift was scratchy. The predicted winds were never materialized and I belly flopped on my landing again.
Here I am looking to the Grimming. If conditions this year had been equal to last year I would have got beyond it into the Enns Valley and maybe around to the Dachstein. This is the big target.
The annoying thing about flying is how quickly a good flight wears off on you. I was already fidgeting the next morning as though I had achieved nothing the day before.
Becka said something very mean to me last night: “You seem a lot more dissatisfied with life since you took up hang-gliding again.”
This needs sorting out. My original notion had to be to treat hang-gliding like skiing, where you go abroad on holiday to the appropriate place and do as much of it as you can to get it out of your system, and then come home and get on with normal life. But it’s not quite working out like that.
The final flight in Austria was in rough conditions and didn’t go anywhere, but the landing was perfect, like I was on autopilot.
Then the weather became rainy and normal for Austria, and we were into the depressing phase of bringing things down the hill and tidying up after expo.
We got away from the campsite at 5am in the drizzle and caught the 10pm Dunkirk ferry to Dover, although I did insist we stopped at the McDonalds in Zweibrucken because that’s where the previous car stranded me for two days in May.
It was the highlight of the journey.
It rains and rains and just won’t stop. It’s also gotten pretty cold and I’m having to wear all my clothes that aren’t damp from lying in the tent. The last day of warm sunshine was six days ago where I stood on takeoff for 2 hours as paragliders wafted past and went down in the totally dead air of that day.
See the smile? I want more flying. Some canyoning would be good too, but it ain’t going to happen on this trip.
When I finally took off I flew in a direct straight line across the valley beyond the highway and golf course, and then had to walk 5 miles back via an ice cream stand to Base Camp for a lift back up the hill, after which I drove down, fetched my glider, and drove back up again for the walk up to Top Camp (the Stone Bridge).
Here’s the outside view of Top Camp:
And this is the inside:
It’s both a rock and a hard place with nothing in between, but it is still better than tents because it is larger, cavernous, and not like a box of damp fabric that progressively rots things as each day passes.
I dropped into the far end of Tunnockshacht down to the new connection to Arctic Angle. Becka was away with the Austrians on a different expedition and couldn’t warn me that it was going to be an unutterably deep one. That wasn’t the problem. The problem was getting terrifyingly stuck in a U-bend crawl while weaseling around the C-leads waiting for the guy with the drill to rig a rope traverse along a ledge of an undescended shaft to access the phreatic continuation. Then we surveyed about 100m until it crapped out, and hauled ourselves back out by 2am.
I forgot to take any pics, so here’s a photo of a nosy horse’s nose:
On Tuesday I went to the newly discovered Balconyhohle. (The horizontal entrance is from a ledge within the side of a hole.) I was cold and had to keep eating. We killed a couple of going leads there too, but there’s enough unexplored ways on to keep this one spreading further underground. This has been the big find of the expedition. It’s a lot of work to keep up with the mapping.
Here’s a picture from the walk back to the carpark from Top Camp in the morning:
Since then I’ve been working on the Adaptive Clearing stay-down linking killing the bugs one at a time while all my HSMWorks buddies have been at a big planning meeting in Copenhagen this week. It seems like an endless grind. Anyway, I don’t plan to go there again, and the ferry between the UK and Denmark is being terminated this September.
One of the things that crashes the system is when the A-star linking can’t find a way to connect from point A to point B, and spreads out through every single cell in the dense weave until it runs out of memory.
One obvious solution is to generate a weave that has a wider cell spacing and solve the routing issue in it, but this is too complicated. I worked out another way, which is to deny it access to most of the interior cells of the fine weave that are nowhere near the boundary or on the theoretical direct line route. The A-star algorithm is so powerful that it will find a way round, even though the domain would look so much more complicated. This initial result becomes the starting solution for the linking path, on which the PullChainTight() function is called. This is actually a bad name for it. It should be called RepeatedlySpliceStraighterSectionsIn(), but this discription wouldn’t remotely be so compelling to the imagination.
This will get implemented only if absolutely necessary. The thing about the linking routine is that it does not need to work 100% of the time, because it can always fall back to the old way of retract linking, which is what everybody puts up with right now, so it might not be worth expending too much effort for the last 2% of awkward cases where the reliability is going to be questionable anyway. In software development the trick is to know when to stop.
Time to work on some cave surveying software today. Maybe I’ll get a flight in tomorrow. Hope so.
Saturday, August 9th, 2014 at 8:16 am - Hang-glide
A week of sulking and being neglected by Becka while she went caved solidly came to an end yesterday when the weather broke and I got a four hour flight from Loser back to the Grimming, where I got to last year.
It was almost carbon copy of my 3 hour 2013 lucky flight, but this time I had better gear and I knew what I was doing — which was good as the conditions have been far more demanding in terms of low cloud base and scarcity of thermals below 2100m.
Here’s the picture in 2013:
Here’s the picture now in 2014 with comfy neoprene bar-mits, an airtight harness that actually fits so I can stretch my legs and fly at the right angle, and an android phone running the astonishing XCSoar with its automatic zoomed in thermalling mode. The helmet and cheap sunglasses remain the same:
Here’s the flight track with the Grimming on the right followed by a long uninterrupted glide towards home:
Becka came along and shared a pizza with me while I rigged.
Every time I do this I have to pinch myself that this is even possible.
A tandem glider pilot gave me a 75% chance of getting up in the conditions. I let him go first to spot the lack of thermals for me, and barely survived when he went down in the initially cloudless conditions. Once I was high and conditions had developed I was able to fly cloud to cloud while deep in the mountains.
I could have gone far if I wasn’t so obsessed with getting to the Grimming where I got swarmed by sailplanes.
The phone with XCSoar comes with a camera that’s better than anything else I own. I can take pictures with it if I don’t get too distracted or do something stupid like stall the glider trying to get a shot of the horizon. Here’s a picture of the Loser Plateau where Becka has been caving.
We zoomed in to one section, and this is plausibly the tarp protecting the entrance of the stone bridge bivi cave.
The cave was extended with a connection made to a smaller cave this year, and the total system is now 104kms in length, making it the second longest cave in Austria. When I get bored with flying, maybe I will go back to doing more of that. I do need to work on the cave drawing software a bit more.
Meanwhile, at the machine tool work, the bugs and crashes are being reported at a fast pace. I have got to get this working 100% by October. That’s the deadline I have set myself.
Thursday, July 31st, 2014 at 10:05 am - Adaptive
We’re having some classic Austrian weather right now. It’s been rodding it down since 5am. I’ve been eating Egg And Chips enough times for it to lose its special status.
Most everyone else is caving at the minute. I haven’t seen Becka in 5 days. I’m waiting for better flying weather.
This is a great time to get some work done on these pesky stay-down linking in the Adaptive algorithm.
Here is an example of the A-star linking path calculated in its setting of the rest of the cutting toolpaths, so you can see how it fits in. The path must traverse through the area without colliding with material that hasn’t been cut yet. This image is of the first iteration. There’s a secondary process which pulls the path of light blue dots tight within its structural matrix once it is connecting in the right direction.
What I mean by the right direction is the way that the path rolls off the preceding path and rolls on to the next cutting path. I can calculate the shortest path reliably now, but it would sometimes result in going 180 degrees back on itself if it’s shorter to go round the circle, so the trick is to artificially insert a circle of exclusion that it has to avoid as it finds its shortest trajectory.
This worked well most of the time, except that the path would sometimes go the wrong way round the circle. It doesn’t know any better. It just finds the shortest path which it can. So I inserted this radial blocking line to block off paths that started off the wrong direction.
And of course sometimes the radial line becomes a liability and the stupid shortest path thing has to go all the way around it when it should be coming in to the path nice and smoothly. I just worked this one out this morning.
It takes ages to discover these errors in the data, looking at unusual tool motions in real examples, and trying to separate them out into the debug development environment so they can be analysed and plotted.
In computational geometry, if you can’t see it, you can’t debug it. In the real world you’d hope that a corporation that depended on vast quantities of computational geometry would have a dedicated team helping programmers visualize their messed up algorithms, so they don’t have to hack up crazy things like my “webgl canvas”.
I’ll spend the rest of the day getting to the root of this one, I guess, and then be one insignificant step closer to finally getting this out of the way.
I don’t deserve to enjoy any flying until I do. Nor do I deserve another egg and chips.
Sunday, July 27th, 2014 at 7:34 am - Hang-glide
I could spend ages reminiscing about the last three days of flying, but then I wouldn’t get any work done. I do now have a dozen gigabytes of video on the disk to be archived. Maybe it is something I will watch in real-time on a big screen when I am old and crumbly.
Here’s a nice edited video of Flight#2. More interesting than most as it was often close to terrain.
After this I walked back up the hill on foot to get the car. It took 2 hours.
Monday, July 21st, 2014 at 9:23 pm - Uncategorized
The internal downpipes from the roof in our house have caused dampness and other problems for over a year. I finally found out why after I noticed it was leaking six hours after it had stopped raining.
First I chiselled a hole through the floor and discovered a void underneath where we thought there was bedrock. No wonder it’s so cold in this house all the time. It’s now a long term project to entirely remove the floor and insulate it.
Monday, July 14th, 2014 at 3:20 pm - Hang-glide
At some point I’ll have some more interesting things for reading about, but at the moment all I’ve got are fun things for me.
This includes another semi-successful quick kite surfing lesson in very light winds where we learnt how to do an emergency pack down of the kite.
Then I hang-glided on two consecutive days. Thursday was overcast. I flew around for three hours mostly alone not far above the ridge. Just filling in airtime.
And then Friday was no wind. Everyone was standing around in the sunshine and gassing to one another. I’ve seen this story before. Pretty soon there’s going to be one big thermal and lots of wind. People are going to let it pass, then get ready and wait for the next one… and there won’t be a next one.
This has happened to me about half a dozen times.
I don’t care how hot it is. I got ready and on the front to take my chance. I’m not afraid to go down if I get it wrong. It’s better than having to pack up at the end of the day having not flown. And for once I got it just right!
Except of course I glided straight back down and walked back to the hill for 8 miles until one of the other glider’s cars found me and picked me up. I’ve now ordered a copy of 50k or bust to tell me what to do next.
I’ve trouble enough keeping my logbook up to date, so here is a page from it with names of the guilty removed.
Now I’ve got a week of potentially doing useful stuff before going to CUCC Expo in Austria.
Sunday, July 6th, 2014 at 3:18 pm - Cave
The Tour de France did their first stage through Yorkshire, crossing Buttertubs north of Hawes. This is quite a long way from Bull Pot Farm where we stayed, so I got a lift most of the way out and completely failed to find Becka and the others on the hill. (Luckily, I was carrying the lunch.) Who knew there would be such an incredible crowd and no phone signal on such a bleak moor? It was more packed than the Col d’Aubisque when we saw the Tour three years ago.
The ridiculous caravan was the same, albeit shorter and with not so many freebies being chucked out. You got to admire that corporate consumer product sculpture that gets paraded all up and down the countryside.
It was a really biting cold wind in the open. At least it blew the midges away. Take your pick. It’s a bad year for midges.
The leader Jens Voigt came through much earlier than the pack, ten minutes after an unexplained flyby of four helicopters.
This was further up the hill from the real packed crowd on the steep bit where there was barely any room for the riders to squeeze through.
Then it was time to clear the hillside. It became apparent that every man and woman that owned a fancy bike anywhere in a 200 mile radius was on that road trying to get off at the same time. All the cyclist spectators overtook me on the road back to Ingleton in a steady stream, because I’m really quite slow. There were no other cycles on the stretch back to the farm: just me. Some DVDs of the live race had been burned and driven up the track by the time I got there, so we could watch the whole race and all the stuff we’d missed while we had our tea.
Apparently that’s the real way to do it: sit in a cafe or pub on the route watching the live race on the TV, then step outside for the split second it goes past in real life, then get back in and carry on watching on the screen while you enjoy your beverages in the warmth.