How Cruise Ships Work (Part 3): The Bridge and the Engine Room

October 8, 2018


It’s like back in the days when we were little children. Grandpaw’s almost mystical tool shed was strictly off limits, but we were just dying to have a peek, weren’t we? Now that we are all grown up, Grandpaw’s gadgets are old news, but there is still a place or two on a cruise ship that remains like a pie in the sky for all of us obsessed by ships.


It’s the heart of the matter, it’s where it all happens, it’s the real deal. And if you are anything like me, you would gladly give away a day at the spa, a dessert buffet and even two, or the latest Marvel flick in the movie theater, just to spend a precious hour down in the noisy engine room of your favorite cruise ship. But life being proverbially unfair, modern cruise lines rarely allow their passengers to enter the bridge or the engine rooms of their ships, unless the visit is part of a specially organized guided tour. Some ships have a window from which passengers can observe what’s going on in the bridge, but only if they promise not to disturb the officers. Which is really hard, when you badly want to touch everything…


So until the next time someone lets me out of sight and I make my umptieth attempt at trespassing to the engine room, let’s have a quick virtual tour of a cruise ship’s most forbidden and exciting parts.



The Bridge


The bridge is the brain of the ship. It is from there that the captain and his officers command and maneuver the ship, keep watch for other vessels or potential hazards, and navigate through the oceans. 


Deck Officers on the Bridge of a Cruise Ship 


For twenty-four hours each day, the bridge is occupied by two Deck Officers and two Able Seamen, traditionally in four-hour shifts. The main job of the Officer of the Watch is to monitor the ship’s systems and surroundings, and to ensure that everything is running safely and smoothly. During extreme weather, docking, or other special cases, the Captain of the ship is also present on the bridge to guide the deck officers.


The term "bridge" comes from the time of the paddle steamers, where a bridge was built above the two paddle houses that used to hold the paddle wheels. This way the skipper could observe both wheels, while moving freely between the two and giving out commands. On today’s cruise ships, the bridge is usually on the upper deck in the forward part of the ship and extends over the sides of the superstructure, allowing deck officers a view to the sides of the ship as well as down to the waterline. The side extensions are called bridge wings and often have a glass flooring for better visibility.


Glass-floored bridge wings of the Harmony of the Seas


The bridge houses a number of important nautical devices and information systems for command and navigation of the ship.


Satellite Navigation


The signals emitted by special navigation satellites are picked up by the cruise ship through a special antenna. On board, a computer converts these signals into the exact position of the ship at a given time. On large ships, the position indicator is constantly recorded in a so-called electronic nautical chart.


Satellites also enable automatic positioning systems on modern cruise ships. The positioning system is controlled from the bridge and it uses GPS to ensure that the ship stays at a defined location. When the captain defines a position where the ship needs to remain for a while without anchoring, the system automatically maintains the ship in position by using the bow and stern thrusters.




Modern cruise ships carry a gyro compass and a magnetic compass. The gyro compass consists of a fast-rotating disk, usually positioned in a gimbal. It is a non-magnetic compass oriented parallel to the axis of rotation of the earth and thus indicates the north-south direction.


Gyro Compass


The gyro compass is more accurate and reliable than the magnetic compass and is therefore the primary reference point for steering the ship. The magnetic compass on board is more prone to inaccuracies and it serves only as back-up.




The word radar stands for Radio Detection And Ranging. Radars are devices that allow us to locate distant objects from a given location, regardless of visibility and weather conditions. The radar emits electromagnetic waves to an object, then receives back the reflected echoes from that object, and interprets them based on distances and angles. These interpretations enable us to determine where an object lies, and in some cases even what its contours look like. In the shipping industry, radars are used for monitoring traffic in ports and coastal regions, for collision protection, for collecting weather data, and for navigation.


Speed Log


Speed logs are devices that measure the speed of the ship. There are two main types of speed logs: Doppler logs and electromagnetic logs.


The Doppler logs send out underwater sound signals. When the sound wave reaches the sea floor, it gets reflected and then returns to the receiver of the log. Due to the movement of the ship relative to the seabed, a Doppler effect occurs and is evaluated by the device. As long as the sound waves can reach the bottom of the sea and return to the receiver, the Doppler log measures the distance travelled over ground. However, if it is no longer possible to use the seabed as a reference, the device uses particles suspended in the water, such as plankton and minerals, to measure travel through the water.  

Doppler Log

The electromagnetic logs create an electromagnetic field in the water around the ship, with the aid of a small alternating current and a transducer. A voltage proportional to the speed of the ship is generated in the water and is picked up by special sensors, which then transfer the information to an electronic device for interpretation. From the electronic device, the speed is then transmitted onto the displays in the bridge.


Echo Sounder


Cruise ships also have an echo sounder, a device used for the electro-acoustic measurement of water depths (sounding). The depth is determined by measuring the time between the emission of a sound impulse (water sound) and the arrival of the sound waves reflected from the bottom of the sea. The main purpose of echo sounders in cruise ships is safe navigation through waters.


Electronic Chart Display and Information System


The Electronic Chart Display and Information System (ECDIS) is a console, built into the bridge of modern cruise ships, which incorporates the main engine safety system, fire control system, monitoring and control system, power management system, propulsion control system and navigation and maneuvering system. The ECDIS allows for navigation of the ship without the need of traditional paper charts. Navigation can be done manually, automatically, or through the Navigation and Command System (NACOS).

Navigation and Command System (NACOS)


The NACOS is the main software used to coordinate all factors that need to be taken into consideration, in order to navigate and maneuver the ship safely. The console is composed of a number of displays showing information from the radars and compasses, data about the course of the ship and planned maneuvers, the current status of the pitch of the thrusters, the speed of the ship, and anything else concerning the steering of the ship. An intelligent autopilot tracks changes in the behavior of the ship through navigational sensors. If the ship drifts off its course due to strong winds, for example, the system automatically responds to correct the change by sending signals straight to the engine room. Once the signal is received by the engines, the rudder or thrusters of the ship are activated and move to the position given by the system. The displays on the bridge show both the angle of the rudder or thrusters, as well as the rate and the radius of the maneuver in progress.



The Engine Room


The engine room is the heart of a cruise ship. It is here that pistons hammer and crankshafts turn to propel the ship forward. It is the loud and oily place where the Chief Engineer and his team work around the clock to ensure that everything is running smoothly. It is the engine room of the ship that allows for the luxuries of air-conditioning, electricity, and plumbing on board cruise ships.


Engine Room of Royal Caribbean's Allure of the Seas  


In future articles we will have the chance to explore the contents of the engine room in all the excruciating detail that they deserve, so to all the techies out there – I’ve got you covered. Just stay tuned.


Most larger ships have more than one engine room to house their machinery. The arrangement of the engine room can vary depending on the type, design, and size of the ship. For stability reasons, the engine machinery is typically placed as low as possible in the ship’s bowels and often takes up several decks in height. The machine rooms are split into watertight compartments, each housing different machinery.


Today’s cruise ships operate on diesel or diesel-electric engines. Their operating principle does not differ much from the old days of coal steamers, except for the medium used to generate power. While back in the day ocean liners used steam to move the engine’s pistons, modern cruise ships use diesel fuel. Today’s diesel engines are composed of the engine unit itself, gearboxes, shafts and generators. Some ships also have shaft generators which create electricity from the turning movement of the propeller shaft. The electricity is then used in the cabins, on deck and in the kitchens.


Wärtsilä SAM Electronics Shaft Generators 



The latest generation of cruise ships are equipped with diesel electric engines. Instead of the more traditional engine-shaft-propeller arrangement, in this case the engines are connected to generators to create electricity. The generators power electric motors, and the electric motors move the propellers.


Aside from the engines and generators, the machinery that occupies the engine rooms includes pumps and heat exchangers for engine cooling, stabilizer fins and their motors, as well as the ship’s bow thruster system.


Since all of the equipment in the engine room is highly dependent on electricity, modern cruise ships also have back-up generators, usually located outside the main engine room, to protect them in case of fire. While these generators cannot produce enough power to keep the ship moving, they produce enough to keep some of the vital functions of the ship running, such as powering the emergency lights and the communication and navigation systems. In case the back-up generators fail, cruise ships are also equipped with a back-up battery that allows some of these functions to continue running for short periods of time. 


All the machinery in the engine rooms is monitored in the Engine Control Room (ECR). The ECR is a room full of screens, lights, alarms, and switches from where the current operational status of every piece of equipment can be checked.


Engine Control Room


The main switchboard of the ECR is used to distribute the generated electricity to where it is needed on board. The ERC is also where the engineering team comes together to discuss and plan the safe running of the engine rooms, to take decisions in emergency situations, to consult the technical manuals and drawings of the ship, to restart certain pieces of machinery if necessary, and to maintain communication with the bridge. Communication between the ECR and the bridge is crucial for the safe operation of the ship, especially during docking, moving through shallow waters, maneuvering, and changes in the course or speed of the ship.


This concludes our three-part overview of how a cruise ship functions. Now that we have covered the basics, in future articles we can explore all the specifics to our hearts’ content. As always, don’t hesitate to leave your constructive comments below and feel free to suggest topics you want to know more about – chances are I want to know more about them too!


Stay in touch and I’ll see you next time!


The Shipyard







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