Some interesting observations on the ocean liner and its changing shape and purpose embedded in a fine article by Ian Jack in the Guardian on Saturday. The article was prompted by the news that the QE2 is to be retired next year to become a shopping centre in Dubai. The liners built since it was launched in 1967 have become squarer and squatter.

The reasons are largely economic, but also have something to do with the changing nature of the liner business. In 1967 the QE2 was built to take passengers across the Atlantic, even though the last year in which more people crossed the Atlantic by ship than plane had been almost a decade earlier, in 1958. The reason for the curves is that curved ships, apparently, are more comfortable to be in at 30 knots in a rough north Atlantic sea.

But since the arrival of the container ship, ships have been about capacity, and a square hull can carry more than a round one. The economics of the cruise business are similar; more capacity means more passengers, who also spend more while on board. Jack writes that 16 million people took a cruise on around 280 ships in 2005, and the largest operator, Carnival, is sufficiently optimistic about the growth of the market to order 10 more cruise liners from an Italian yard at around £25o million apiece. They carry 3,500 passengers a time and another 1,300 crew. (Obviously, in a market like this, an affluent older population helps).

But where will they go? As he says, the Americas destinations around the Caribbean and Bahamas are already full, and the Mediterranean going that way. Some lines have built their own destination islands from nothing, and Ian Jack speculates that they might build their own destination ports with the full luxury consumer experience on tap (“like a sunny version of Heathrow”). As a holiday experience this seems a little circular – in an age where travellers are demanding greater authenticity – to be completely rewarding, but maybe there’s enough of a niche to fill the boats. Looking at the set of trends which influence the cruise business, it has the feel of a business which is near its peak. But no doubt Carnival would disagree.