Several projects have been commissioned in recent years to cut cruise ships in half, like in the video below, so they can be extended. But why not build a larger vessel from scratch?

We’re gonna need a bigger boat.

If you’re the owner of a cruise ship in 2015 and this thought is on your mind, then you have more than one option for upsizing your vessel. Indeed, building a brand new one from scratch is enormously expensive – from several hundred million dollars to more than $1bn (£660m) for the largest ships.

Alternatively, you could always cut the one you already have in two and fit an extender section. You can see what that looks like in the video above of Blohm+Voss in Hamburg extending a Fred. Olsen ship called the Braemar.

It sounds wacky, but several cruise ship companies have been doing it lately because the process is surprisingly cost-effective. Cruise line MSC recently ordered four such extensions from the Fincantieri shipyard in Sicily at a cost of $227 million (£150 million), far less than the price of four new ships.

Doing this added 31m to the Braemar’s length and increased capacity from 729 cabins to 988.

The process involves slicing through the ship’s structure and hull, gently pulling the two sections apart on rollers and then slotting the new piece in between. Finally, all three sections are welded tightly together again so the whole ship can be repainted. At Blohm+Voss, the project takes just two months.

Bigger ships are sought-after because demand for holiday cruises is growing rapidly worldwide. According to the Cruise Lines International Association (CLIA), passenger numbers rose to 22 million in 2014 from 13.1 million 10 years earlier. A recent survey of cruise passengers found that the trips were increasingly popular with younger travellers and suggested that the all-inclusive nature of cruises, making it easier planning and cost management were among the reasons why they preferred them as holidays.

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