Cruise Ship

Overview

A large cruise ship is the heaviest passenger machine ever built, and by part count one of the largest machines of any kind. The yards that build them, Meyer Werft in Papenburg, Chantiers de l'Atlantique in Saint-Nazaire, Meyer Turku, describe a ship of this class as roughly 2.5 million parts, erected from about 80 prefabricated blocks of up to 900 tonnes each. The arithmetic is dominated by repetition: ~2,700 Prefabricated Cabin Modules at ~600 parts apiece account for over 1.6 million parts on their own, and each Hull Block carries thousands of Cable Cleats and Pipe Hangers on top of its welded plates and profiles.

At 220,000+ gross tons, 360 m length and 18 passenger decks, the ship is functionally a floating town: its own 60–97 MW power station, water and sewage works, a hotel for 9,000 people, and four production Main Galleys turning out up to 30,000 meals a day.

Hull construction

The hull is not built bow-to-stern but block by block. Steel arrives as plate, is plasma-cut and welded into stiffened panels of Hull Steel Plate and Hull Stiffener, panels become sections, and sections become grand blocks framed by Web Frames. Before a block ever reaches the building dock it is pre-outfitted: Pipe Spools, Cable Tray Section runs and welded Machinery Foundations go in while the block is still open and accessible, because work done in the shop costs a fraction of the same work done overhead inside a finished ship. Each block then carries thousands of Pipe Hangers, Penetration Collars and Cable Cleats, an outfitting population that, multiplied across 80 blocks, runs to hundreds of thousands of parts.

Cabins

The single biggest contributor to the part count is the accommodation. Cabins are not built on board: a Prefabricated Cabin Module is assembled on a factory line ashore, complete with its Cabin Wet Unit, a one-piece GRP bathroom pod with Vacuum Toilet, shower and basin, leak-tested before it leaves the factory, plus B-15 fire-rated wall panels, furniture, a Cabin Door pair and pre-terminated wiring. The finished module is slid into the hull on rails through openings left in the side shell and connected to power, data, potable water and the 0.4–0.6 bar vacuum sewage main through quick Connectors. Each module runs to about 600 parts, around 400 of which are the screws, clips and trim fixings of the Cabin Fit-Out Fastener.

Power and propulsion

The ship is diesel-electric throughout. Four to six Diesel Generating Sets, each a Medium-Speed Diesel Engine of 12–16 cylinders coupled to an 11 kV alternator, feed two Main Switchboards located in separate fire zones, a split required by SOLAS Safe Return to Port rules so that a single engine-room casualty cannot black out the ship. Each engine is a large machine in its own right: sixteen Cylinder Units around a 20-tonne Crankshaft, with a high-pressure Engine Fuel System, a Lube Oil System, a fresh-water Engine Cooling Circuit and a Charge-Air & Exhaust System system feeding the two turbochargers.

Propulsion is three Azimuthing Pod Propulsors, steerable underwater pods, each containing a 14–20 MW synchronous motor directly on the propeller shaft, hung from the hull on a Slewing Bearing and azimuthed by a Steering Module. The pod replaces shaft lines, rudders and stern thrusters in one unit; the monobloc Propeller pulls in tractor configuration ahead of the pod body. Service speed is about 22 knots on roughly 60 MW of propulsion power.

Hotel systems

The HVAC Plant conditions on the order of 200,000 m² of interior: five centrifugal Centrifugal Chillers feed a ship-wide chilled-water loop serving 24 zone Air-Handling Units and about 3,000 cabin Fan Coil Units, through 2,600 Duct Sections hung on some 12,000 Duct Hanger fixings. HVAC is typically the largest hotel-load consumer on board.

The four main Main Galleys are stainless-steel factories, Combi Ovens, flight-type dishwashers and thirty-odd welded counters each, plus a couple of thousand stainless fittings per galley. The Public Spaces Fit-Out fit-out (theatres, atria, restaurants, promenades) is contracted out zone by zone to turnkey interior specialists and consumes seating by the thousand, 800 Glass Balustrade panels and around 24,000 Interior Fasteners.

Safety

SOLAS requires lifeboat capacity on each side for 37.5% of all persons on board, met by 18 Lifeboats of up to 370 seats each, launched on gravity Gravity Davits; inflatable rafts and marine evacuation systems cover the remainder. The hull is subdivided into watertight compartments and vertical fire zones, and the newest ships must be able to return to port under their own power after a fire or flooding casualty in any single compartment, the design driver behind the duplicated switchboards, separated engine rooms and triple pods.

A ship of this class takes about 30 months from steel cutting to delivery and costs $1.4–2 billion, with roughly 10 million labour-hours across the yard and its subcontractors.