Complications arise because of dizzying arrays of city rules governing size, style and even underwater design, which have changed over the years and are different from canal to canal. Also, the sole Dutch bank that finances houseboats provides money only for the physical boat, not for its space in the water.

A key problem is the limited space on Amsterdam’s canals. There are about 10,000 houseboats in the Netherlands, Mr. Bakker said, with about a quarter of those on Amsterdam’s canals. Waiting for a new spot — without buying a boat that ensures one — can take years.

Many houseboat owners use private financing, he said.

Sander Rutten and his wife almost went broke rebuilding the 112-foot Coaster Mado, which carried wood and salt in and out of Scandinavia after it was built in 1932. But the wharf that was in charge of the rebuilding (the Coaster Mado was completely revamped last year) went bankrupt and Mr. Rutten, who is an expert in heating systems, had to lead the renovations, together with a young shipbuilder.

The result is a beautiful, fully functional family home that happens to look like an old freighter. An open-plan eating and living area can be opened to merge onto the deck. The bedrooms are spacious and light.

The couple’s three children can either play PlayStation games in the luminous below-deck living room (there is optical fiber internet on many of Amsterdam’s houseboats) or dive off the sides of the boat, depending on the weather. The old mast serves as an attachment for a swing.

Despite the hardship and the fears that the project would never be realized, Mr. Rutten says he has no regrets.

“Look at this view,” he said. “How can you beat this?”