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January 18, 2012

Canal des Deux Mers: Castelnaudary to Gardouch

A private boat emerges from the Écluse de Laurens

Canal du Midi

This day we woke in Castelnaudary’s pretty port.  For a moment we toyed with staying longer; we had found a nice spot.  But before long our restless curiosity returned.  The lure of crossing the canal’s high point pulled us back onto the water.

There is a significant technical challenge to route a canal between two seas.  Inevitably, a waterway of this type must cross a divide, the “parting of the waters”.  A divide is a high point; it is the ridgeline where water flows opposite directions to the different seas.  Think about this for a moment.  Without mechanical intervention, how do you get water to flow to the top of a ridge?  Divides are, after all, one place on earth where you will never see a significant river.

Obélisque de Riquet

At the behest of King Francis I in 1516, Leonardo da Vinci examined the feasibility of building a canal across Languedoc.  Leonardo identified supplying water at the summit as a major hurdle to such a canal’s construction.  All subsequent proposals for a Canal-du-Midi-type waterway to link the Mediterranean Sea and the Atlantic Ocean were plagued by this concern.  Indeed, without a major construction project no one could demonstrate with absolute certainty that an adequate water supply could be brought to the highest point of the canal route.  In the 17th century even the amount of water needed to maintain a waterway of this magnitude was at best an educated guess.

Pierre-Paul Riquet’s conjecture was that a dam set well up on Montagne Noire (Black Mountain in English) coupled with a set of collection and supply channels could bring sufficient water to Canal du Midi’s high point.  This needed to be proven.  Indeed, before approval for the full-scale construction of the Canal du Midi was granted, France required that a viable water supply be demonstrated.  Thus the construction of the Canal du Midi began with the raising of a large dam and the excavation the supporting water channels.  At the time this was the largest civil engineering project in Europe.  Saint-Ferréol was just the second major dam built on the Continent.  As Riquet believed, the functioning dam proved to provide water sufficient to service a navigable canal.  Riquet was subsequently granted approval to complete the entire canal across France.

Canal du Midi crosses southern France’s water divide or partage des eaux near the village of Le Ségala.  On the western side, a raindrop flows to the Atlantic Ocean; on the eastern side of the divide, the rainwater ends up in the Mediterranean Sea.  The canal crosses the geographical divide in the midst a 5 kilometer-long pound fed by Saint-Ferréol and held between the Mediterranée and Océan locks.

Between our morning start at Castelnaudary’s port and the Mediterranée écluse there are four locks including a double and a triple.  We made fast work of the locks and reached Canal du Midi’s highest pound by early afternoon.  Past the Aqueduc de Vasague near the “parting of the waters” we floated the Herault to bank and tied up.

Three chambers of the de Laurens lock being filled at the same time

Climbing the hill from Bassin de Narouze we reached the Obélisque de Riquet.  Riquet’s heirs constructed this monument to canal’s primary contractor in 1827 not so long after Riquet’s canal construction debts were finally retired.  We had to visit Riquet’s obelisk; our journey required us to pay homage to Canal du Midi’s creator.  With Gigi roaming free we dutifully trudged up the hill to base of the memorial.  At the side of the obelisk, we could see for a good distance in all directions.  Below us the tree-lined canal snakes to the west and to the east.  The gentle ridge where the Canal du Midi crosses the partage des eaux is barely perceptible.

Becky's loogie into Canal du Midi's highest pound will flow both to the Atlantic Ocean and to the Mediterranean Sea

Back at the boat we unhooked from the bank.  It was not far before we reached the end of Canal du Midi’s highest pound at the modern location of the Océan écluse.  As we arrived the keeper was busy in conversation with a friend.  Eventually he noticed that we were waiting in the channel and opened the lock’s gate.  For the first time on the Canal du Midi we were locking down; the lock’s chamber was full of water as we motored in.

“Are you sure you want to go this way?” the lockkeeper asked first in French and then in English.

The gatekeeper’s unexpected question made it feel like we were about to cross into another dimension.  It must be unusual for hire boats to cross this way.  We told the keeper that we knew what we were doing.  Of course as usual we really didn’t know what we were doing but at least this time we knew the direction we were headed.  We were heading downhill.

The écluse keeper seemed satisfied with our answer.  He noted the Herault’s registration number in his book and proceeded to tell us in some combination of French and English about the automated locks that we would soon encounter.  That there would be automated locks on this portion of the canal was news to us.  The automation was newly installed and our map book was out of date.

The keeper of the Océan écluse explains the use of one rope to hold the boat in place in the lock.

Before the Océan écluse keeper released the water from the lock he showed us a trick for holding our boat in place in the chamber with a single rope.  Wrap two lock-side bollards with one rope and stand on board the boat holding the rope’s end.  This arrangement makes it easy for one person to hold the barge in place during the turbulent locking cycle.  After the rope lesson and the automated lock instructions, the keeper opened the sluice and let the water flow from the chamber down to the Atlantic Ocean.  When the lock’s gate opened we were free to transition to next dimension.  We were going down towards the Atlantic.

The lock operation cheat sheet

Past the Océan écluse the Canal du Midi was quiet.  It felt like we were now on a different canal and on a different journey.  Of the few boats we saw most seemed to be private boats, frequently sailing boats, fixed on making it to the Mediterranean side for coming the winter.  Before we stopped in Gardouch for the night we crossed through two automated single locks and a double that still had a keeper.

Until this day it felt like our trip across France was just a variation of the standard hire boat vacation on the Canal du Midi.  Somehow the Océan écluse keeper had set the stage.  It now felt like our journey was something different.  When we crossed the divide we left the standard tourist itinerary behind.


Day 15

Start:  Castelnaudary

Finish:  Gardouch

Travel time*:  7.3 hours

Cruising time**: 5.6 hours

Distance traveled:  26 kilometers

Lock chambers transited:  14

Weather:  Clear, warm

At the end of the day, our trip across France was 39% complete based on cruising time and 36% complete based on distance covered.  We had passed through 99 of the 246 locks (40%) of the locks that we would cross.

* The time between the start of the day and the end of the day.

**As measured by the hour meter on our boat.  When the motor is running we were either moving or standing by to move (like in a lock).

1 Comment »

  1. […] don’t feel as historic as the Midi’s ovoid locks.  And, like the locks descending from the Océan écluse on the Canal du Midi, the lock cycle actuation is automated.  Here a pole suspended on wires over […]

    Pingback by Canal des Deux Mers: Toulouse to Montbartier « Another Header — January 23, 2012 @ 12:37 am

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