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Locks What are locks and how to pass them?

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If you have already booked your river cruise or are you thinking of doing it, you will have heard of the locks and you probably don't know what they mean or whether or not they are easy to maneuver. In that case, this article is designed by Danfluvial for you!

The word sluice in Latin means the "separated waters". The locks are hydraulic works of art that allow ships to navigate by joining the two navigable parts with different levels. A chamber, isolated by two doors, in which the water level can be varied, thus allowing boats to go up or down a significant slope in the river or canal.

Crossing a lock is a fairly slow operation; since it is necessary to balance the water levels, first with the stretch of channel where the ship is located and then with the other level towards which the ship will leave. Technically, the height limit that can be overcome with a single lock is approximately 25 m.

Going through locks is one of the most fun parts of the river cruise and allows everyone to get involved. When you go through the first one, you will see that the procedure is simple.

Locks type and operation

Depending on the region of the river crossing, the locks can be manual, electric or automatic; they work exactly the same way.

Manual locks:

  • Check that the water level is adequate; in that case open the doors, if not, you have to fill or evacuate the chamber with the help of the gates. Before starting a maneuver, check that the gates and opposite doors are properly closed.
  • As the doors open, enter the lock very slowly and go through the lashings without knotting them.
  • Open the gates when the boat is properly moored. Open the doors once the level is correct so as not to distort the opening mechanism.
  • Exit the lock, close the doors and lower the gates

Mechanized locks:

They are locks that are maneuvered with the help of a lock keeper.

Automatic locks:

Users use them freely. They are electrified locks that work in various ways:

  1. A detector located on the shore; pass very slowly in order for the cell to detect it as this mechanism is very sensitive especially to the passage of commercial vessels.
  2. A radar fixed on the shore a few meters above the ground.
  3. A control pole suspended in the center of the channel.
  4. A remote control delivered on the day of departure; activate it 300 meters from the lock. Follow the instructions on the remote control.

Enter the locks very slowly when the green light prompts you to do so (the red light should be off). The red light is activated at the entrance of the first boat, if several boats can fit, both can enter at the same time.

When the boats are properly moored, press the blue joystick for 5 seconds. The doors close automatically and the lock closing begins. Tie your boat away from the gates to avoid an accident.

At the end of the lock, the doors are opened. Slowly exit the chamber in order for the cell to detect your exit. If there are multiple boats, go out in a group so as not to be surprised by the automatic closing of the doors.

We recommend you watch the video of how to pass a lock on our website:


 Some tips for good use

The passage of a lock is a simple and very pleasant maneuver if some elementary tips are followed:

  •  Commercial vessels take precedence over pleasure boats when passing the locks.
  • Respect the lockers' opening hours and working hours, which appear on the river maps or which you can request.
  • In certain periods of the year (dry period) the lock-keeper groups several ships together before making the passage. Be patient and understanding.
  • The passage of the locks is free. However, the locker will appreciate any tip or gesture of appreciation. Please note that mooring your boat is not part of the locker's obligations.
  • If the lock has a telephone, the lockkeeper notifies the next lock of his arrival. Inform him if you intend to stop between two locks, to prevent the next one from being prepared in vain.
  • Before reaching a lock, 150 to 200 meters from it, whether you are sailing downstream or upstream, slow down and announce your arrival with one or two honks.
  • If the doors are open upon arrival, you can enter the lock directly and moor the boat.
  • If when you get to the lock there is still a boat waiting to leave, wait for it to leave before starting your maneuver. In this case, moor the boat about 100 meters from the lock so as not to obstruct the operation of the doors, so that the outgoing boat can maneuver safely and thus avoid eddies.

In all cases:

  • Maneuver in slow gear
  • Go up and down stairs with caution as they are often slippery
  • Never jump out of the lock onto the roof of the ship
  • Once the passage through the lock is completed, securely collect the moorings on the deck of the ship.


The dam system has been in existence for more than 2000, they were created so that ships could traverse the dams they originally carried, creating small 'overflow gates' (= narrowing).

From the 15th century on, docks with sea gates appeared on European water courses. These docks are an approach of two gates that allow saving the water lost during each passage (paleo-lock). This system is no longer used, although it was the direct precursor to modern locks.

Starting in the Renaissance, Dutch and Italian engineers such as Leonardo da Vinci perfected this system by working especially on the jambs and the pressure they support. Progressive improvements (guillotine doors, then arched, and from the 19th century cylindrical gates) will make it possible to balance the pressure on the doors and the construction of locks that are increasingly manageable (5 m and more).

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