In London, which suffers from one of the most expensive property markets in Europe, thousands have found alternative housing for less than the cost of a parking space — though it helps if you can repair an engine or plug a leaky hull. Narrowboats, which aren’t much wider than a king-sized bed, have gained in popularity for those willing to sacrifice space and some creature comforts. Moorings on the city’s 100-mile canal network can be had for around 1,000 pounds ($1,284) a year.
The waterways crisscross the metropolis, allowing boaters to live in posh areas such as Primrose Hill and

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