We've seen some absolute monsters that really would qualify as coastal ships. These are single-hull, not the doubled ones. Having said that, we've also seen quadruple barges locked together.

I have been continually fascinated by the seamanship (canalship?) of the masters of these vessels. They seem to be able to spin these things on a dime, using the current on the Rhine to help them. Then on the Moselle, we watched as they negotiated locks with eye-of-the-needle accuracy and delicacy.

And the ferry masters are pretty good at their trade, too, although I think doing 30 or 40 trips across a narrow waterway each day might make the job a tad boring.

We sat on the balcony of our St Goar hotel and watched the cruise boats do their thing as they pulled in to drop off and collect passengers. Again, the masters seemed so nonchalant with their deftness at manouevring these things.

Of course, the Rhine barges are a lifeblood for German industry up and down the river, transporting coal, oil, gasoline and gas in what must be huge quantities every day. It's a slow, almost painful trip for them up, but once turned and heading back downstream, their speed across the ground virtually doubles.

We spoke to another couple on a bicycle tour with their 18-month-old daughter, and Bruno said he had tried on several occasions to hook up a trip on a barge. But the masters were reluctant because of liability issues. Bruno seemed confident that if one had the time and patience, they would eventually find an agreeable captain to take them.

We looked at maybe hiring a canal boat, but the costs are quite prohibitive for us right now. A cruise down the Moselle, for instance, or the Marne, or along canals that are no longer used by commercial traffic is something we would consider in the future. They stop off at the same campgrounds we have stopped at while cycle-touring.