A lock is just a box of water with a gate at each end. Raise the water level, your boat goes up. Lower it, your boat goes down. That is the whole concept, and it is two hundred years old. None of which stopped me from getting it badly wrong the first time, when I let go of the wrong rope in a downhill lock near Dijon and watched our bow swing across the chamber towards a Dutch barge whose skipper was, understandably, not delighted.
So here is the step-by-step I wish I had drilled before that day. Read it before your first lock and you will be fine.
Before you even reach the lock
Get the boat ready well in advance. Fenders down both sides. Have your lines coiled and ready: typically one from the bow and one from the stern, long enough to reach a bollard above you when the chamber is at its lowest. Crew should wear gloves, because canal lock walls and ropes are filthy and a rope running through a bare hand under load will burn it.
Decide who does what. On our boat, my wife handles the helm and holds the boat steady while I work the lines from the side deck, and we do not swap mid-lock. Agree it before you arrive, not while the gates are opening.
Watch the light or signal at the lock entrance. A red light means wait, do not enter. Red and green together usually means the lock is being prepared. Green means come in. Some locks have no lights and you simply wait your turn, especially behind a commercial barge, which always has priority over you.
Going up: a lock that fills
This is the gentler of the two, because you start at the bottom with the chamber empty and low.
- Enter slowly when signalled and move to your allocated side. Stop the boat well short of the front gate; the incoming water comes from that end and pushes you backwards, so leave room.
- Pass a line around a bollard or through a ladder rung high on the wall, and bring the end back to the boat so you can adjust it. Do not tie it off solid. You need to be able to take in slack as you rise.
- The gates close behind you. The lock-keeper, or the automation, opens the paddles and water surges in. The boat rises, sometimes briskly. Keep taking in slack on your line and keep the boat held against the wall with gentle engine if needed.
- As you near the top the turbulence eases. When the water is level with the pound ahead, the front gates open.
- Let your line go, motor out steadily, and clear the lock so the next boat can come in.
Going down: a lock that empties
This one caught me out, and it catches out most newcomers, because the water drops away beneath you and your lines go slack fast.
- Enter when signalled. Going down you start at the top, level with the pound behind you, so getting a line onto a bollard is easy at first.
- Take your line around a bollard at the top edge and back to the boat. As the water drops, you must pay out line steadily so the boat goes down with the water. The classic beginner's mistake is to cleat it off; if you do, the boat hangs from the rope as the level falls and you can capsize or snap something.
- Keep the boat gently against the wall. In an emptying lock the turbulence is usually less than a filling one, but the boat can still sidle around.
- When the water is level with the lower pound, the gates ahead open. Recover your line and motor out.
The rule that keeps you safe going down: never make a line fast. Hold it, tend it, pay it out. The water is falling, and the boat must be free to fall with it.
Automated locks, twist-poles and the eclusier
French locks come in two broad flavours. Many are still staffed by a lock-keeper, the eclusier, who works the gates for you and often runs a little stall selling honey, wine or vegetables by the chamber. A wave, a bonjour and a bit of patience go a long way, and tipping is not expected but buying the honey is appreciated.
Others are automated. Some you trigger by twisting a suspended blue pole as you approach, some with a remote handset the hire base or VNF gives you, some by pulling a rod hanging over the water. The hire company shows you the method for your route at handover. If you own your boat, you pick it up quickly, but the first automated lock always feels like you are doing something wrong. You are not.
Lock-specific oddities
Not all chambers are rectangular. The Canal du Midi famously uses oval locks, where the curved walls mean your boat cannot sit flat against a straight side, so you tend your lines more actively. I mention the Midi's quirks in my first-timer's overview of the Canal du Midi by boat, and if you are heading there, practise on a few ordinary locks elsewhere first if you can.
Depth and dimensions matter too. Most older French locks follow the Freycinet gauge canal dimensions, a chamber about 39 metres by 5.2 metres. Your boat has to fit with room to spare, and on a busy day you may share a lock with two or three other craft, which means rafting up or sitting nose to tail. Be ready to take a neighbour's line.
The lunch rule and the daily rhythm
Locks have working hours, and they stop for lunch. Most run roughly 9am to 7pm in high season, with a firm closure from about 12.30 to 1.30 when nothing moves. Arrive at a lock at 12.35 and you wait an hour, possibly behind boats that arrived before you. Plan your day around the locks, not the kilometres, and aim to be moored or comfortably waiting through the lunch break. This single habit removes most of the stress from canal cruising.
A short pre-lock checklist
- Fenders down, lines ready and long enough, gloves on.
- Helm and line-handler roles agreed before entering.
- Watch the signal: red wait, green enter; commercial barges go first.
- Going up: leave room at the front gate, take in slack as you rise.
- Going down: pay out line steadily, never make it fast.
- Mind the lunch closure, around 12.30 to 1.30.
If you have not done any of this yet, read my complete beginner's guide to cruising the French canals for the wider picture on licences, tolls and boat sizes. But the locks are the bit people fear, and they should not. After a dozen of them, working a lock becomes the most satisfying part of the day. We did 14 in one stretch on the Burgundy summit last June and by the end my wife and I barely needed to speak. That is the goal.
