The cruise industry is booming, and along with it the demand for bigger and better cruise ships every year. To keep pace with the rapid improvements in the industry, and the growing demands of customers, many cruise lines have turned to stretching their vessels, in order to improve and build upon their existing fleet.

What is stretching?

The process of stretching involves what engineers of yesteryear might have thought impossible – the slicing in half of a cruise ship to insert in a new section.

This method allows vessels to gain capacity in a hurry, expanding their space for guests and adding new facilities quickly and cheaply compared to the cost of a new build.

How does it work?

Cruise ships are built in blocks; like Lego pieces. Each of these block is built separately, with duct work, wiring and even plumbing in place for that section. The individual blocks are then welded together, and systems for electric, HVAC and plumbing are integrated. Due to this modular structure, ships can be pulled apart, with new aspects inserted, without requiring a total re-fit of the rest of the ship.

Before stretching can begin, careful maps and charts are made, mapping out where pipes, ducts and cables are to be cut (for reconnecting later). Teams of engineers plan out every move during the multiple-month process of stretching.

Separately, a new block is built ready to be inserted into the space created, with all of the wires, pipes and ducts in places ready to be connected once it’s slotted into place.

The ship is taken into dry dock, loaded onto reinforced blocks and cut in two, in a precisely determined cutting zone.

The two halves of the ship are then carefully separated using an elaborate system of pulleys and rollers, with one half held in place, as the other is slowly (and very carefully) moved away. The new section is then slotted into place, and the ship is welded back together, both inside and out. Systems are reconnected, and any rooms and cabins that needed to be stripped down ahead of the stretching are refitted – this is why refits often occur at the same time as ship stretching.

The whole process takes place over a number of months, and once complete (and the exterior has been repainted) it’s almost impossible to tell that the vessel has been stretched.

Why stretch a cruise ship?

Stretching a cruise ship can add a substantial amount of capacity at a rapid pace, and offers huge cost savings compared to commissioning a new build. Comparing the $950 million price tag attached to recent build of Royal Carribean’s Specturm, and the estimated spend of $85 million for the upcoming stretching of Windstar’s Star Breeze – you can see a clear saving. Stretching is estimated to offer a return on investment in as little as 5 years, offering a clear financial incentive for this innovative form of engineering.

Examples of stretched ships

Royal Carribean’s Enchantment of the Seas was the third of it’s ships to be stretched in 2005, and at the time, the largest ever to undergo the stretching process. A new 73ft mid-section was added to the ship, adding 151 staterooms, and amenities including suspended bridges, a vitality course with 4 fitness stops, an interactive water play area and the first bungee trampolines at sea.

MSC stretched all 4 of it’s Lirica class ships between 2014 and 2015 adding on average 200 staterooms to each vessel, along with extensions to existing facilities and brand new ones. Each ship took approximately 10 weeks to lengthen and refit, at a total cost of £159 million.

Silversea’s Silver Spirit was stretched in Spring 2018, gaining 49ft of midsection and a 12% increase in capacity, as well as an expanded pool deck, spa and fitness area and 2 new restaurants. The whole process took over 500,000 man hours including design work and labour.

A number of ships also have stretching work planned for this autumn dry dock season and beyond, including Windstar’s Star Breeze; which will see 50 new staterooms added and the engine renovated. The MSC Magnifica will be stretched ahead of her 2021 summer season, adding 215 new rooms, including 92 balcony cabins, a new waterpark, shopping area and restaurants.