Cutting massive cruise ships in half and then adding a new section to extend their length is becoming an increasingly popular method for increasing ship size.
Simulation of the ship lengthening process. (Video: Windstar Cruises).
Ships are getting larger, such as the Icon of the Seas launched by Royal Caribbean Group in January of this year. A more straightforward and cost-effective method for operators to increase a ship’s capacity and accompanying profits is to make existing ships larger, according to New Atlas. With an average cost of around $80 million and just two months of downtime, operators can cut a ship in half, add a new section designed to fit perfectly with the ship’s bow and stern, weld them together, and increase the number of premium cabins to generate revenue over the coming years.
The process known as jumboization is not a new idea nor exclusive to cruise ships. In fact, the term originated after World War II when some shipbuilders sought to lengthen warships. Today, many shipyards specialize in adding sections 24 to 40 meters long to existing cruise ships, with the main processing work done in a matter of weeks. First, engineers design the new section. Each detail among the thousands of pipes, wires, cables, and ventilation ducts is designed to fit the new section, ready to interlock perfectly at both ends during the joining process. This way, the ship can maintain its existing functions. Next, the shipyard fabricates the new section. Sometimes, these sections are launched and towed to a dry dock for assembly.
Next, the ship is moved and positioned precisely over a series of sliding plates on a pinned metal track on the dry dock floor. Each small sliding plate is a hydraulic mechanism capable of lifting 1,000 tons and applying lateral force to move along the track. The extension of the ship can involve up to 50 sliding plates.
With the ship placed on the sliding plates, the dry dock is empty and the ship is resting on a new mobile support system. Workers then begin to cut the ship in half. Laser guidance beams are used to ensure accuracy down to the millimeter. The cutting sequence is carefully planned due to the ship’s enormous weight and structural pressures.
Since 1977, 21 cruise ships have been lengthened this way.
The ship’s hull is cut by automated cutters that handle flat surfaces like the hull and deck, while skilled workers manage curved surfaces or complex shapes. Both use common acetylene welding torches to cut through metal. Once the ship’s hull is cut, the sliding plates begin coordinating the process of separating the two halves far enough apart to insert the new section in the middle. The entire ship is cut and separated in about two days. After this step is completed, the edges of the bow, new hull section, and stern are precisely aligned thanks to the lifting and shifting capabilities of the sliding plates. This is when the welding process begins.
Workers use a combination of electric and stick welding. This is the stage where accurate cutting is crucial since the maximum gap that can be welded between the two surfaces is only a few millimeters, thus cutting as close as possible is essential. The crew must ensure there are no errors to prevent water from seeping into the hull and to ensure the entire structure can support the large ship during rough seas. Next, they will reconnect all cables, pipes, wires, and many other systems. A separate team is responsible for repainting the ship to cover weld marks and imperfections on the exterior.
The shipyard is responsible for the structural integrity and seaworthiness, but operators also need to thoroughly inspect all electrical, mechanical, and hydraulic systems on board to ensure everything is reconnected properly. They must also conduct sea trials to demonstrate the strength and maneuverability of the newly lengthened ship.
The entire process from the ship’s arrival at the dry dock to its operational approval takes about nine weeks. Since 1977, 21 cruise ships have been lengthened this way.
