Freesteel Blog » Weekends

Tuesday, September 10th, 2019 at 11:47 am - - Kayak Dive

The Jurassic coast has been the top of my list for a big kayak diving adventure for a while. Enough so that I invested in a copy of a 2015 guidebook called Dorset Dives (review article), which is more of a picture book with some dodgy dive site information, rather than a quality guide book with some crappy photos to break up the text.

It was not great weather at the start of September, but this is the time to take advantage of the gap between the start of the school term and the University term when the season is winding down. We’re trying to economize now that Becka is working half-time and has too many days not to “waste” being at home.

We drove down to Reading on Tuesday 3 September and then on to Durdle Door Holiday Park (via a grumpy dive cylinder filling station on Swanage Pier) with two dive kayaks on the roof, two full sets of dive gear including four tanks, three drysuits, two wetsuits, a cheap pop up tent, a trangia cooking stove and two bikes rammed into the car getting crushed by all the stuff slumping onto them. We had to return after we set off to pick up the sleeping bags I’d forgotten.

The tent pitching ground is in a crow-infested forest. Crows poop just as much as pidgeons, except it’s brown so you don’t see it on the ground. They also make a lot of noise. We walked down to Durdle Door and attempted to walk barefoot on the gravel beach to Bat’s Head. This hurt too much, so we put our sandles back on, which instantly filled with gravel and didn’t make much difference. We got changed and swam through the Bat’s Hole (natural arch) to the other beach and felt better for the cold water experience.

That evening we walked to Lulworth Cove where the chip shop was already closed, but the pub wasn’t.

Thursday 5 September was calm enough weather to kayak-dive out of Lulworth cove going west towards Durdle Door. Going in the other direction was not allowed as it’s a live firing range on weekdays.

First dive was on a promising looking reef out from Bat’s Head called The Cow. The other reefs in the same line with Durdle Door are: The Calf, The Blind Cow, and The Bull. There was nothing interesting on The Cow, so we gave The Bull a miss and went straight to the dive on Durdle Door, where the guidebook says this:

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Saturday, August 31st, 2019 at 3:13 pm - - Canyon, Hang-glide

The dates were set by Becka planning to spend one night in Interlaken on Friday 2 August between four weeks on the CUCC caving expedition in Austria and a one week caving expedition up a hill called the Sagistal to the east of the city, followed by a weekend at Sinterlaken the Swiss Caving Congress. This was then intended to lead into two separate week-long caving expeditions back in Austria (Plankamira and Datchstein), capped by a caving holiday down in the Ardeche in early September. However, I said: “Could we do something together that’s fun for me, because you ought to have got enough caving done by then?” and so, at great sacrifice, a canyoning holiday was scheduled.

I drove out to Interlaken on my own with my hang-glider on the 30 July, booked into Manor Farm 1 at £28/night for a narrow slot, and showed up the next morning at the Landplatz Lehn where I knew there was an english professional tandem pilot employed by hang-gliding interlaken to fly tourists off the hill at the rate of up to six flights a day, which is a heck of a lot of work.

Their van took me up to their favourite Amisbuhl takeoff between the trees (the taxi rate is 7Fr), helped me over the tedious 15 minute carry up a private road, and took three complete rounds of passengers airborn in the time it took me to set up and stand on the edge gibbering about doing a nil-wind takeoff. I have an experience of completely screwing these up with two crashes on take-off at Ager last year.

They say they have 300 flyable days at Interlaken, which is true because there’s enough shelter that they can fly in almost any condition, between bands of rain and cloud. They’re not all good flyable days.

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Monday, August 12th, 2019 at 3:58 pm - - Flightlogger, Hang-glide

I thought I had published this long form article in the blog until I looked for it. Turned out I’d accidentally left it on github here. Text is below the fold.

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Monday, August 12th, 2019 at 3:32 pm - - Hang-glide

After many days at Interlaken, generally flying down from various takeoffs and ramps, I got the opportunity and nerve to finally fly at Fiesch, where I got to see over the glaciers.

Flight 1 was easy; up and across the ridge into the Goms valley, thus saving me from the landing field at the bottom of takeoff. At the end of the flight I was caught in the convergence in the middle of the valley that took me back to 2800m. The only way down was to go to the edge of the valley and circle down.

Flight 2 was harder as I had to get really high first and then there was no lift for miles along the side of the valley until I was saved by a very slow climb on a particular ground collapse. There were some moments of zero-G on that flight. No matter how high I got, there were still always rocks above me.

Thursday, July 25th, 2019 at 3:46 pm - - Kayak Dive

Stop doing and start blogging!

Yesterday I got out on the wreck of the Resurgam in 1879, which then sank while on tow in the Mersey Bay, only be discovered 116 years later. It was propelled by a coal powered steam engine and was lit by candle light.

You’d think that the people of the day would have seen that electric power had to be the way forward for submarines. The inventor, George Garret, appeared to have done a lot of marine tech in a life that was shorter than mine, but then emigrated to America in 1890 to become a rice farmer, which seems a bit of a waste.

I dived it with a half empty tank (on a 100bar) because I was too incompetent to fetch the right one out of the garage. Luckily it was a shallow dive and I could go easy on the breathing at the cost of giving myself a headache for the rest of the day. The water was pretty warm, so I skipped gloves, which meant that I got nipped by crabs when I forgot to look where I put my hands.

Here’s the remnants of the propeller in my hand:

Here’s the other pointy end:

Here’s the remains of the conning tower:

Maybe if I took off my tank I could have jammed myself down inside. It’s pretty tight.

There was one hole on one side by the sea bed, from which this lobster made a successful escape from the other diving pair who were trying to catch it for their dinner:

Then I bothered a tompot blenny by poking it out of its hole. It slipped round to the other side of the tower only to meet a second blenny who was not pleased by the territorial incursion:

I wonder if there’s been any experiments with territorial species to find out whether they use natural boundaries to demarcate their areas, and to what extent a nipped intruder understands where the line is drawn. Or maybe the animal territories are not actually areas, but instead single perching places from which to leap out and attack intruders that they can see, and that’s the key.

I remember a talk about fiddler crabs on the beach who have little burrows that they run back to for safety. The experimenter wanted to find out how they navigated to their hole and put down piece of sandpaper and fishing line which they used to quietly drag the unsuspecting crab away from its hole and prove that the crab used its sense of direction in a polar coordinate grid centred on its hole.

Then I surfaced and got fetched by the boat.

Wreck of the Calcium

Quick subsequent dive on the Wreck of the Calcium, also not deep, but with a proper fill in the tank.

First we fall overboard backwards so that our mask is not swept off by the water.

Who doesn’t love a good swim-through filled with fish?:

Here’s a short video of a flatfish with its funny bulbous eyeballs slipping away beneath a school of other fish.

There were a couple small shy conger eels in the boiler:

The lobsters were too numerous and brave to be frightened away and saved:

I used to think the gopro was a waste of money, but compared to the alternatives it can be a lot clearer. You can see the red camera light flashing on my forehead. All four of us divers had headcams.

At one point I lost my headcam (the retaining string wasn’t properly on round my neck). Here’s the episode of it falling off and being kicked around.

I found it quite enjoyable watching this video, though shame it wasn’t the right way up so it saw me coming back to fetch it. These blur-o-vision FPOV headcam movies don’t seem to be as engaging as you’d expect. Next time I’m on a dive where I’m absolutely sure I’m going to get back to where I started, it would be neat to just park it somewhere looking out so it could see the divers receding from view, leaving everything to the fish and wandering crabs, before gradually seeing the divers emerge back from the distance.

Reminds me of a trip a few years ago when someone’s helmet cam came off his head on a kayak dive in Loch Sunart, and it was filmed the perfect express elevator to the surface where it was picked up by Becka:

I got to think of some way to stop it floating off, and securing it to whatever I’ve made. Maybe I’ll have to line off from it to be safe. The jiggling on the line when the divers are out of sight might add a bit of suspense and anticipation.

I got back with a horrible Diesel fume headache, attempted to play underwater hockey, but gave up. Then went round to DoESLiverpool to check on my robot, which had gone offline because somebody had left it out of the charging dock.

Tuesday, July 9th, 2019 at 10:29 am - - Kayak Dive

Things go on. We did some excellent kayak diving up in St Abbs that was planned to take advantage of a student who could be in a sea kayak on the surface so we’d feel more at ease going deeper and further underwater than we’d normally venture on our own.

Our main mission was to see a wolf fish, frequently sighted on Black Carrs rock below 20m.

Here he is:

This was along the low cut down that runs due east from the rock, in a horizontal crack behind an upstanding rock. It’s probably always the same fish that everybody sees. He caught my eye as we were searching along the bottom, and I propped up a cairn on the spot so we could come back to him after pushing on a bit deeper to the brittle star carpets.

And here’s my cairn marking the spot of the shy fish’s lair.

My pics make it look a lot less pretty than what it was it was to be there in the water, but they work for me as evidence.

Our support kayaker (plus visitors) was present when we went down at this deep spot.

As usual they were nowhere to be seen when we came up. They tend to get bored and find something else to go look at, because it all seems well from the surface to non-divers who don’t know what disasters might be unfolding below the water.

The wolf fish dive was on the Tuesday 2 July 2019. It was a stiff northwest wind and swell that made it impossible to go near the coast and explore the caves anywhere further round towards Pettico Wick.

The weather and water visibility conditions had not been the best we had hoped for, but the trip had to fit into a narrow time window of people’s availability and Becka not being on a caving expedition.

We stayed overnight in a three bed shared room at Marin Quest, which was a little expensive, but it paid off well when on Monday over breakfast the boat skipper was able to give us the position of the wreck of The President at this spot: 55°52’10.0″N+2°04’25.0″W/@55.8694568,-2.0741817 in a very sheltered channel to the south of Eyemouth directly in line with a fence style.

Here’s us loading up the kayaks at the convenient concrete access path near Greenends Gully.

We overshot too far south on the paddle out. The cliffs further towards Burnmouth look well worth exploring, but we didn’t have time for that.

The dive on The President was excellent, progressively finding bigger and bigger bits of scrap steel until we finally hit the boilers. Otherwise, there was not much life.

Sam, our look-out student, spent the time watching dolphins doing leaps and flips close in.

Here’s a blurry shot from a Mark One blurry gopro to prove he saw something jumping.

After a tank changeover at the carpark, we hauled our kayaks against the wind and waves to the north of Eyemouth and into the shelter of Weasel Loch.

Sam took my wallet shopping for junk food as we did a shore dive out of the channel to look for Conger Reef.

We didn’t find the reef, so here’s a picture of a flatfish and small lobster in the rocky wasteland it was supposed to be.

We circled back to the cliff wall, which was spectacular, huge, deep and overhanging, and then found the way back in. I could spend all day shore-diving out of this loch popping in and out of the water trying to get my bearings. Maybe I’d eventually find this reef.

Back by the car we changed into wetsuits and I gave Sam a try dive, during which we saw a small lobster on a ledge at minus one metre.

Stepping back in time to Sunday, when Becka and I arrived in St Abb’s (before Sam came), we dashed out for an afternoon dive on Wuddy Rocks.

Becka managed to haul down the anchor at the start of the dive, but couldn’t stay down because she didn’t have enough lead.

Normally this is my fault for not putting enough on her weight belt, but this time it was because she’d forgot to put it on at all!

Once sorted out, we found the way into the tunnels where we tried out our new new diving torches, one wide and one narrow angle.

Up till now I’d been using a Dive Scurion Light, which Becka has appropriated into her caving gear. I’ve nearly lost or broken on a couple of occasions. I’m glad not to bother with that thing again, because a burn time of 12 hours is no use when dives are at most a couple hours a day. It’s huge and has a dangly wire between the battery and the headset.

Torches are a good investment, because one of the points of diving is to see things. Over the years they’ve become smaller and brighter, until maybe soon you’ll just have some bridge specks on the fingertips of your gloves that will emit rays when you cup your hand in a particular way.

Then we did a second dive and went looking for Cathedral Rock from the shore. Here are the instructions from Marine Reserve booklet:

To reach Cathedral Rock follow the main gulley between Broad Craig and the harbour wall. Keeping Broad Craig on your left and the training pool on your right, enter a narrow gully which drops down to approximately 5 metres. Swim to the right around the narrow gap and proceed until you reach a pile of angular boulders. From here head approximately 45 degrees to the right, passing over kelp forest on the way, until you reach a small rock face covered with dead men’s fingers. Swim past this rock keeping it on your left shoulder into a sandy gully. Cathedral Rock is on your right, just over a large boulder.

Not surprisingly, I didn’t find it.

The Lawson Wood diver guide (whose position for The President are out by 3 minutes of arc) describes the route like so:

Swim over to Big Green Carr [this is the wrong rock -ed]; keeping it to your left swim south in line with the reef. At the end of the reef you should see a low lying ridge extending at right angles in front of you; pass over this and you will meet a wall that curves to the left over a tumble of large boulders. With this wall to your right, you are now swimming east and you will reach Cathedral Rock in about 12 yards.

The problem with these descriptions is that everything is relative in terms of what constitutes a large boulder or a sandy gully. This is no use underwater where the visibility is such that you can only see one thing at a time. If you swim into a boulder that’s 2 metres tall, then it’s large if is alone on a rubble strewn plane, but small if it is surrounded by 8 metre high blocks. When you can see only than 5 metres distant, you can easily persuade yourself either way, and therefore the description is of no use. It might as well have said: turn left at the boulder that once had an octopus on it in 1998.

Had I realized that these descriptions were so utterly defective, I’d have looked online, and found this dive description:

The one thing you must do on this dive is trust your compass, so take your bearings and follow them!

On entry head right and at the end of Broad Craig there is an area of almost white gravel (actually shells and worm-casts); Take a compass bearing of 120degrees and swim approximately 30m to reach the site.

We had driven partway up to St Abbs on the Saturday and slept overnight in a layby on the A7 before seeking out breakfast in Berwick upon Tweed. The cheap eating place was packed out, so we wandered into town and hit upon the Mule on Rouge, which is where I’d be hanging out every day if I lived in this town. Unfortunately, Becka had just decided that we were now on an economy drive, because I haven’t been paying my house bills for a while, so we shared one single bagel.

On the Saturday I had been taking my telepresence robot around Makerfest Liverpool in the Central Library. It’s possible that this toy had something to do with the cashflow crisis.

Isn’t it cute?

Wednesday, May 29th, 2019 at 11:57 am - - Flightlogger, Hang-glide

I think I’ve not been blogging ongoing projects are not working. A long running one that I have failed to report here is this dabbling with the RTK GPS system, which I learnt about by researching precision agriculture, having been tipped off about it by a guy from sixty-5 when I was working out of farset labs in Belfast earlier this year.

Anyway, in theory one can log the raw data from these ublox M8T GPS chips, use the open source RTKLIB software to process the rover GPS against a base station GPS to get a 2cm accurate time series (with a lot of help from the rtklibexplorer blog, and then plan to put one of these rover stations in each wingtip of a glider.

And this would have all been fine if one of the wingtips ESP32 devices that receives and transmits the UBX data from the GPS to my phone through wifi didn’t keep failing. I finally found out what it was: the tiny sheet metal antenna had snapped off so cleanly that you couldn’t tell it was missing.

Here is a picture of my three devices. The 2 rovers go into pouches with their own batteries and get tied into the wingtips.

Anyway, it was a rubbish and rough flight that I did last Tuesday, never getting higher than 2600 feet. Meanwhile, Becka was doing her Welsh 3000s walk across 15 peaks all of which were higher than I managed to fly, and got a photo of this Brocken spectre on the peak of Snowdon at 8am, having set off at 5am from the car.

I was tasked with being a few kilometres further down the road to provide the second breakfast and some sandwiches for her further journey.

No I wasn’t going to do that walk, after my experience with the Lakeland 3000s. Walking too far in one day is annoying, especially when you are constantly being told you’re not going fast enough.

The logical consequence of having more strength and always wanting to do more than anyone else is… that other people will want to do less, and this is going to be a disappointment.

So I went flying, and RTKLIB processed my one working GPS track, like so:


(Blue is the phone GPS and orange is the RTK gps.)

I was going to show some correspondences between the RTK GPS altitude and the barometric altitude when suitably filtered, but my interacting plotting system broke down. There are a lot of oscillations in the GPS, which I don’t understand. Will get back to it.

Monday, May 20th, 2019 at 11:57 am - - Kayak Dive

I’m carving out some valuable time from the other stuff to blog some notes and records.

The car failed its MoT inspection with 3 condemned tyres. (Some kind of bump in them that I couldn’t see.) I had an unhappy evening because I thought this had trashed our kayak diving weekend in Anglesey.

Apparently the dangerous bulge is in this picture here at bottom inside:

Yes, normally back in the 1990s I’d have driven the car anyway, because who’s going to know? But now with all the MoT records being computerized so you can’t shop around for a garage who might overlook the flaws, and all these automatic number plate recognition cameras on the motorways, I was for sure I was going to be busted by the police on our way out.

Fortunately Becka phoned up a kwikfit garage and I took it round in the morning for some new tyres at a high price, but it was worth it. We kept the fresh receipt on the dashboard as evidence that the issue had been addressed and didn’t encounter a problem. Even though we didn’t need it, it’s good price to pay for not to have this eating your mind during the whole drive.

After a stop off at Vivian Quarry for some air-fills (£4.50 for only 200bar and a long time to fill), we dropped in on the Astral Ship for an inspection.

We concluded that it wasn’t a robot friendly place, so I took it away and we were lucky to get my robot into someone else’s car for the ride back to Liverpool. More on this story some other time.

It was now 4 o’clock, and we got a kayak dive out from Cable Bay to the Euphraties, which was swarming with large spider crabs and had mounds of chain and other wreckage that blended in with the rocks so well you couldn’t tell, except by their form, what was natural or man-made.

Then we headed off late to the Tyn Rhos Camping Site Ravenspoint Road and ended up on the wrong side of a locked gate because we hadn’t approached it from Ravenspoint Road (idiot). The Liverpool Canoe Club were spending the weekend there and some of them had paddled to the Skerries durinig the day (one of the things on our bucket list). One of the other parties had passed us coming in while we were going out for our dive. They didn’t stop off to watch, as no one is particularly interested in kayak diving. In the morning we tried to see if there were any trips being planned that we could dive in the direction of, as it gives peace of mind to have a bit of company on the surface when you are underwater, but nothing presented itself. So we were back to our original plan of diving the Kimya, which I have been trying to get a decent dive on since 2004!

The wind had picked up from the northwest (it was supposed to be northeast on the forecast) and there was a bit of chop. The May bloom was overdue. It all looked like it would be another failure.

But we got there. After much anchor dragging of anchors, shouting and checking the GPS on my expensive phone in a pelicase (all my waterproof GPS’s are bust), Becka seemed to hook something at last. (After the dive she understood my outrage that it had been so difficult to hook — the wreck is massive and full of holes.)

Just as we were going down the line, a dive boat showed up. That made me feel more comfortable.

If everything went tits up, they’d probably pick up the pieces. It’s a 3km paddle from the nearest landing and there are no fishermen on the headlands, so it’s a pretty lonely spot round about here. No one is ever going to see you.


Becka collected the anchor from the bottom and carried it as we circled the wreck twice. I thought the lifeline to our kayaks was going to get tangled continually, but she skillfully kept it running free. I had thought at the start about tying the anchor to a good spot on the wreck, but it was so big you wouldn’t be sure of getting back to it again.


There were a couple of swimthroughs, and a huge hold that we sank down into towards the end of the dive. Luckily the divers from the boat hadn’t been in there to stir up the silt by then. Little splashes of bright colour from nudibranchs on any surface you cared to focus on.


And so we surfaced, climbed back on our boats, chatted with the other divers (who were from St Helens) and arm-power hauled our way back to Porth Cwyfan (the cove with the white church), and then hoofed the kit across acres of sharp low-tide rocks to the shore.

Now we would have had our tea at that spot, except that the place is very much in earshot of the Anglesey racing circuit, whose noise diary for 19 May 2019 gave their No Limits Motorcycle Track Day a noise category 2. It was pretty bad.

We drove to Newborough Warren where the guy collecting the £5 entrance fee had already gone home, and brewed up some tea just over a sand dune from the carpark (unfortunately melting the handle on the trangia tea-pot in the process).

Then, of course, we had to walk out to and along the whole length of Ynys Llanddwyn, scrambling up and down the rocks at the far end.

I was knackered.

Becka accused me of getting soft and complained that we had done nothing all day.

Wednesday, May 8th, 2019 at 7:00 pm - - Hang-glide

Lots of adventures that have gone unreported on the blog for the last few months, including a month long stay in the city of Belfast, including a couple of dives in Strangford Lough. I’ve been putting stuff in twitter/goatchurch instead.

I haven’t finished writing up my logbook, but anyway I was on a hang-gliding competition last week where I got 12th place in spite of levels of fear before takeoff that made me question whether it was all worth it.

It turned out it was. There were some lovely flights from Builth Wells, Hay Bluff. And then there was Merthyr. Becka was there to pick me up from where I landed, and I sometimes made enough of a distance for this to be worth it.

Here are some quick pics.


Acting as a wireman to put off the fateful moment when it’s going to be my turn.


Getting low on Merthyr Hill in the grey after an hour and a half of flying in the rough air.


Finally getting up to cloud-base, at which point I decided I was done with this place and went straight off downwind.


I landed two hills back with some curious cows. Not such a result that day.

The gopro failed on the other two days, so no in-air photos are available.

I got a lot of stuff to write about, like RTK GPS, ESP32s with MQTT asyncronous mDNS capabilities, Sonoff POWs, differentiating time-series values by curve fitting polynomials. The trouble is none of it is working too well, so I’m preferring to work on it rather than report it. I’ll force myself to hammer some stuff out in the next few days whatever.

Tuesday, November 6th, 2018 at 6:51 pm - - Hang-glide

Quite a lot of work in the last week (especially at the weekend) reading a big book called Tailless Aircraft: Their Design and Characteristics, published 1994, translated from German.

The blurb on the inside cover reads:

The authors are uniquely placed to compile the first practical and comprehensive treatment of this fascinating branch of aeronautics. They have for many years collaborated on the practical and theoretical development of flying wings, applying themselves to sailplanes and powered designs ranging from models to full-size craft. In 1988, together with Klaus R, they received the “Berblinger Award” from the City of Ulm for their investivation into the design for an optimum tailless hangglider.

What the heck is the “Berblinger Award”?

The winner of the 100,000 Euro Berblinger Flight Competition was declared on Sunday 17 April, in the Ulm town hall. In all, 36 participants competed for the prize, which focussed on the use of innovative, ecological and resource-saving technologies. Of the 36 applications received, 24 aircraft were initially admitted to the competition. 13 aircraft started successfully; due to insufficient financial backing, technical difficulties or the absence of the appropriate flying licenses the remaining competitors were not able to take part in the practical phases of the competition, which was carried out at the AERO global for general aviation, in Friedrichshafen. Eight participants successfully completed the exercise of flying from Friedrichshafen to Ulm.

Two anniversaries were celebrated with an extensive programme of events during this weekend in Friedrichsau Park and the Adlerbastei: 200 years ago, King Friedrich 1st gave the Friedrichsau Park to the people of Ulm. In honour of his visit, Berblinger performed his attempt to fly across the Danube.

Who the heck is Albrecht Berblinger?

One of Berblinger’s inventions was what appears to be a hang gliderKing Frederick I of Württemberg became interested in his work and sponsored him with 20 Louis. He tried to demonstrate the glider on the evening of 30 May 1811 in the presence of the king, his three sons and the crown prince of Bavaria. The king and a large number of citizens waited for the flight but Berblinger cancelled it, claiming that his glider was damaged. The next day he made a second attempt. The King had left by this time, but his brother Duke Heinrich and the princes stayed to watch. Berblinger waited so long for a good wind that a policeman finally gave him a push and Berblinger fell into the Donau (Danube).

It sounds like the experience on some of my takeoffs.

But enough of that rabbit-hole.

I’ve been attempting to replicate some of these graphs and diagrams from the book, like these ones:

After many days and many attempts, I got to this matching version:

This was not helped by the mistake in Formula (2.7.5)!

I could not replicate the other four lines for the “neutral point” (some details about dc_l/d(alpha) has been left out).

In the process of this I have wasted no pencil and paper, and proved the power of SymPy, which I think all mathematics should be written using.

The details are all on the Horten sailplanes Jupyter notebook. It’s probably a good thing I don’t have the technology to inline mathematics into this blog.