Mons to La Louvière
The next part of our plan was to experience the historic boat lifts on the old/historic Canal du Centre. For Ian, this was probably his most highly anticipated section of the entire three-month cruise. The combination of scenic territory, small waterway and spectacular old machinery promised to be a delight. After experiencing these amazing feats of engineering, Lisette happily concurs – this was truly remarkable.
First, we travelled along the initial part of the Canal du Centre. Along the way, after leaving Mons, we had used several locks, one being 10 m deep, which we shared with a commercial vessel and a small cruiser. Floating bollards made this an easy rise and we added this deep lock to our list of ‘first’ experiences.
A brief cruise along the main canal brought us to the Thieu lock, 6 m deep, our entry point to the historic Canal du Centre and an automatic lock as it turns out. We hadn’t anticipated this and on arriving, had tried to contact the éclusier on the VHF. But looking around we noticed a pole overhanging the canal and the penny dropped – we were responsible for controlling this lock.
We hadn’t used an automatic lock before, so this was pretty cool and another first for the day. Lisette had to reach out and push a long green lever up, to initiate the lock sequence. Apparently, these are common in France but it was a surprise and new to us. So Lisette stood way out on the foredeck and when Ian got the boat close enough, Lisette grabbed the pole and gave it a mighty push upwards. Buzzers sounded, and the lock began to empty, with water being pushed out below the gates. When the lock was ready to receive us, the gates opened, with a green light signifying it was ‘ok to enter’. The lock itself is buried in the hillside, and entered via a narrow opening, under a concrete barrier. It’s like cruising into a dark cupboard. Once inside, with each of us having our bow and stern ropes strung around small bollards, Lisette pushed the blue pole that was against the lock wall hard up until it engaged, and the gates began to close.
The locks filled slowly, and as we rose, we both had to keep moving our ropes from one bollard to another, all of them buried in the wall of the lock and mostly rather slimy as they spend a good deal of time underwater. At the top, we found ourselves in a lovely pound – the waiting basin for the first of the Ascenseurs, number 4.
A bit of background
The Ancien Canal du Centre features four mechanical lifts (ascenceurs) and for many years only one, #4, has been operating for pleasure boats. A spectacular accident had closed #1 in 2002 preventing through traffic. The enforced closure was used to allow restoration and repair of the other three ascenceurs. The damaged ascenceur has recently been repaired and we knew that all lifts were now operating. Travelling through all four was now possible but only on weekends, so we had timed our arrival for a Saturday.
When we describe these lifts, some ask, “What was there before?” The answer is “Nothing” – at least in a waterway sense. These ascenceurs were not built to replace an existing flight of locks as has been the case for similar lifts elsewhere. The desire of the Belgians to connect the Meuse/Sambre river to the Scheldt had seethed for many years but had been frustrated by the 96 m difference in height that would have required too many locks to make it practical. Added to this, there was no substantial source of water that could be used to replenish the water lost as the locks emptied towards the Scheldt.
The most challenging section was a 66 m change over seven kilometres between the towns of Thieu and La Louvière. It was too steep for conventional locks. The Belgians became aware of mechanical lifts that had been built in the UK and commissioned their designer Edwin Clark to establish the feasibility of building similar lifts at Thieu.
The study was a success and the most formidable piece of waterway engineering in the world at that time began in 1885. The first lift opened in 1888 and the three other lifts were built in succession. Delayed by political dithering and then WWI, the full set of lifts and hence the entire Canal du Centre finally opened in 1917. For the next 85 years they carried up to just over a quarter of a million tons of cargo each year.
Decommissioned in 2002 when the new Strepy-Thieu lift was opened, the group of ‘Ascenceurs Ancien” were granted UNESCO world heritage status in 1998 and preserved in an operating condition.
How do they work?
The principle is as simple as it is elegant – the beauty of the concept then enhanced with a seemingly intricate tracery of mechanical framework.
Two caissons (essentially bathtubs) are mounted atop huge pistons. Each piston is connected hydraulically and the pair is set so that as one caisson is at the top of the lift, the other, the counterweight, is at the bottom. A vessel enters the bottom caisson (it displaces a weight/volume of water equal to the boat’s weight, so the weight of the caisson does not change). Gates are lowered, sealing off the caisson and then about 30 cm of water is allowed to fall into the upper caisson. This adds about 75 tonnes to the top caisson and the extra weight causes it to fall, while the hydraulic interconnect with the bottom caisson forces it to rise. Virtually no energy and very little water used. The operation of the lifts uses about 100 cubic metres of water for each cycle. If this was replaced by a single, deep (17m) lock, it would consume over 4,000 cubic metres each and every cycle, nearly a 98% saving in water consumption.
There are four hydraulic lifts each lifting (or dropping) you by 15-17 metres. Each lock chamber is 43 m long and 5.8 m wide. This is sufficient for commercial barges carrying cargo of about 350 tonnes, which represented a standard size for locks at that time – similar to the Freycinet standard locks in France.
At each of the lifts, there is a pump house that a small amount of water from the upper level and use it to raise a heavy weight to the top of a column of water. This compressed column of water provides hydraulic power to operate gates and ancillary equipment. Truly a wonderful feat of hydraulic engineering.
The iron and steelwork was functional rather than decorative but viewed now, the interconnecting frames of the towers and the red brick pump houses framed by the walls of the canal dam is both spectacular and beautiful.
Up the lifts
We contacted the éclusiers and were told they would prepare the bassin for us. We cruised carefully into the caisson, tied up and the rear guillotine door dropped down. Very soon, there was the oh so gentle sensation of movement. We were ascending and above us, the counterbalance caisson was descending. Quietly, we rose while watching the canal below us drop away and vistas of the countryside appear.
The only noise being the whoosh of water cascading into the descending caisson as it topped up to increase its weight. This was a seriously fantastic experience!
At the first one, one of the guys asked Lisette (“Bonjour madame …” – all conversations were in French – way to keep practising!) how far we wanted to go today. We knew there was an Italian Cantina partway up and had decided we would treat ourselves to a meal out for once. The place is very well known so the guy immediately knew we wanted to use Ascenseur 4, 3 and 2, because the Cantina is located between numbers 2 and 1. We would take the final Ascenseur, number 1, the next day, Sunday.
It is hard to describe but was super cool. Imagine being lifted up 17 metres, but when you are up there, there is a whole new community living there, with their houses at that level, although you can also see the previous, lower community, as you cruise along this new stretch of canal. It was very pretty, lined with trees, and apart from the vibrant green duckweed that flourishes in these still canals, a lovely spot to cruise.
However, under the duckweed was a denser type of weed. As we approached the next Ascenceur (#3), we were asked to moor up against a large barge to wait for our turn to use the lift. As we came up, there were several cruisers just in front of the barge we were to moor against. As Ian applied reverse to slow, nothing happened other than a violent vibration. As we were fast approaching the cruisers in front, with the imminent prospect of our 50 tonnes rear-ending them, we ceased trying to moor and steered around them. Eventually, we were able to get a bit of reverse and backed into the mooring. At that time, we were unsure of what was happening.
When we were called into Ascenseur #3, we again realised we had trouble with reversing and hence slowing Catharina. So Ian’s usual routine of applying a little reverse once we are in the lock/caisson didn’t work and, in #3, we sailed slowly forward until we hit the wooden gates at the far end of the caisson. After some checking by the concerned Ascenseur team and some considerable embarrassment for the two of us manning Catharina, all was judged good, no damage done, the gate was dropped into place and up we went.
Waiting to be allowed to enter Ascenseur #2, we did some analysis of the problem. As we cruised along we switched between forward and reverse and when Lisette saw loads of weed being thrown off behind us, Ian decided that the problem was probably weed around the prop. We’ve since found out this is a common problem with ‘stringy’ weed – but new to us at the time. So, this was the third learning for the day. Somewhat reassured, off we went
to the third hydraulic lift, which we entered very, very cautiously – but reverse now seemed to be working and we locked up without uneventfully. We then cruised to our resting place for the night, directly outside the Cantine des Italiens.
Italian migrant workers provided a large amount of labour for the mines and heavy industry in the region around the canal. The original buildings, built in 1946, were used to house workers but have now been converted into a restaurant and museum highlighting the immigrant workers. Rather similar to the situation in Australia where migrant workers from southern and central Europe were brought in to build the dams and waterways that form the Snowy Mountains Scheme. The restaurant was simple, the food plentiful and reasonable cost – while at the other end of the restaurant there was music and dancing. A very welcoming atmosphere.
The next morning, we took the bikes off and cycled back past Ascenseur #2, back to number 3, where we could see the impressive hydraulics in action. The twin turbines are fed by water pressure and operate periodically to raise the weight that pressurises a tower of water which, in turn, powers the operation of the ancillary systems in the ascenceurs. Simply, fascinating.
The pleasant ride alongside the canal and up and down past the Ascenceurs further added to the attraction of this experience. All the way along there are information notices in French, English and Dutch covering the history and technology of this canal system.
We arranged to enter Ascenseur #1 later that morning, and finished our run of these impressive historic boat lifts, mooring just outside along a rather sterile quay.
As we were nearby, we were able to pop down once night fell to take some photos of the illuminated Ascenceur #1.
We had originally planned to head onto another magnificent feat of waterway engineering, the inclined plane at Ronquières. But, as our generator was still defunct, we thought that we would make tracks to a shipyard close by that might be able to help diagnose and fix the problem. We would be returning along this canal later, so we could fit in Ronquières then.
So, off to the shipyard…