Liz has taken up pole dancing. Not in a nightclub or anything... she does it on the bow of the boat, much to my great pleasure and amusement.

Okay, okay... if you read these blogs regularly you'll know by now that there's always a catch, and in this case that's literally what it is. But first, Canal Locks 101: An Introduction...

On a canal, a lock is that marvel of engineering that enables you to take your boat up or downhill. It allows canal traffic to go from A to There regardless of how much the local landscape rises or falls. And basically it does it by filling and draining according to need. So, if you are travelling 'downhill' on a canal, you will enter a lock full of water, the gates will close behind you, and then 'paddles' underwater in the gates ahead of you will open. Slowly the water in the lock drains out until you reach the same level as the canal ahead, at which point the gates in front magically open and off you sail. The reverse happens when sailing 'uphill'. Got it? There will be a test.

But how the locks do this depends a lot on where they are, or how many of them there are together. When the First Mate and I began this watery adventure we headed off down the Saone and Rhone rivers. On the Rhone the locks are huge and designed to take commercial barges as well as piddly-little boats like ours. The biggest we encountered was a lock called Bollene, which drops you a full 22 metres from one level of the Rhone to the next. It's like an aircraft hangar. Luckily it is, like all the Rhone locks, controlled by a lock-keeper, or eclusier, who sits in his or her control tower and operates the hydraulic paddles etc for you. You do nothing but make sure your boat stays where it should as it descends, and that your ropes don't snag. (Hence the very sharp knife that sits by the throttle, just in case...)

On the Canal du Midi - and more recently the Garonne - we have encountered much smaller and less-formidable locks, many of which raise or lower you only two metres or so. These are far more typical of locks on the French canals in general.

The French waterway authority - the VNF - used to provide eclusiers for every lock, but these days many of them are automated (the locks, not the lock-keepers). The remaining eclusiers probably realise their days are numbered, which is undoubtedly why some of them look a bit sad.

The first eclusier I ever saw in France was a revelation; I think I'd expected a moustachioed, beret-wearing overalled man of small stature, whereas she was actually about 19, blonde, wearing shorts and with her shirt tucked up into her bra so that her tummy could catch some UV. She was gorgeous. I fell in love, with canal boating, there and then.

Unfortunately, all the other eclusiers I've seen since have paled by comparison, and have been much closer to the stereotype I'd envisaged, though without the berets. Some of the women don't have moustaches either. Their temperements range from a surly oh-mon-dieu-'ere-we-go-again attitude, to smilng cheery helpfulness. Most say Bonjour, some engage in conversation. One, seeing our Kiwi flag, shouted "Go ze All-blacks!"

At this time of the year, with not much canal traffic, they don't have a lot to do. And even when a boat is locking through, it's not a quick process, so while the lock is filling or draining the eclusiers are either on their mobiles, doing something mysterious inside their cottage, or - quite frequently - pulling weeds out of the ground. This happens so often we've taken to calling them constant gardeners. But whatever their demeanour, we always say Bonjour on arrival and Merci, au revoir on leaving. Occasionally we try and chat to them.

I asked one eclusier, based at quite a pretty lock on the Midi, whether the plane trees along his stretch of the canal were safe from the fungus, but he shook his head sadly and told us no, they were for the chop. Then he patted the newly-installed remote control panel beside the lock and informed us that when it came online he too would be for the chop. C'est tragique, was all we could say, to both sets of circumstances.

Which brings us back to the locks, how they're operated, and pole dancing. So the waterways authority, the VNF, are slowly but surely handing over responsibility for lock management to us the users, and they're doing this in various ways. One is that they supply a lockside control cabin, in which are some buttons and instructions in French, English and German on what to do. For those who can't read there are arrows beside the two main buttons, so as long as you know which direction you're going you'll have no problem.

Then there are the Grey Sentinels. These obelisks stand to attention beside the lock and simply have a big green button, which you push. The sentinel somehow knows whether the lock needs filling or emptying. However like the cabin, it doesn't say Bonjour. There's another sneakily-clever automated system that operates by way of sensors in the canalside, and when your boat triggers them the lock leaps into action automatically, but we have yet to come across one of these.

And finally there's the mid-stream pole. This hangs from a cable that stretches across the canal and is attached to a switch at the top. All you have to do is twist it and the lock ahead prepares for your arrival. But when I say 'all you have to do', what this actually involves is me guiding the boat's starboard side deftly towards the pole so that Liz, who stands on the starboard bow, can equally deftly catch it, twist it, and let go of it before it pulls her overboard. This is where the entertaining pole dancing comes in, and it's fun for all.

Except of course for the rapidly-disappearing human eclusiers, who increasingly are having to look towards the local job centre. Which inFrance, ironically, is called the Pole Emploi.