The bridge of any cruise ship is manned 24 hours per day, and is the operational centre of the ship. It is manned by highly trained and qualified Deck Officers on a four hours on, eight hours off basis. The watches comprise of two Deck Officers and two Able Seamen. The Officer of the Watch is responsible for maintaining continuous visual and audible lookout and taking the ships helm when required. During busy periods (i.e. arrival into port, bad weather or heavy traffic), the manning of the bridge is supplemented by the Captain and Staff Captain.
The bridge is the location of the navigational and primary safety systems onboard the vessel. In this blog I want to give you an insight into the purpose of some of the equipment, the operation of the bridge and the work of the personnel who navigate your ship.
The fully integrated bridge system comprises of a series of sensors and items of equipment including: Gyro Compass, speed log, satellite navigation, radar, echo sounder and ECDIS (Electronic Chart Display and Information System). The information from these sources is all displayed on one user friendly console, allowing the Officer of the Watch immediate access to important information.
The ships compass is one of the most important pieces of navigational equipment onboard. There are 2 types of compass aboard most cruise ships, a Magnetic Compass and a Gyro Compass.
The Gyro Compass is an extremely sophisticated piece of equipment and consists of a spinning disc rotating in azimuth. It will always point to a point in space above the meridian of the earth. This means that it is extremely accurate and an error rarely exceeds 1 degree high or low. The Gyro is housed in a separate room, with repeaters on each bridge wing and on the centre line. The Gyro Compass is the main aid to navigation. The Gyro Compass is used by the helmsman as a reference for steering the ship, the heading is also fed into the auto pilot system so that the ship may be steered automatically.
The Magnetic Compass is used as a back up. Being magnetic it is susceptible to suffer variation and deviation. The compasses are frequently checked for errors by taking a bearing of celestial objects.
The Engine Room
To give an example, Emerald Princess operates using a diesel electric propulsion system: 4 large and 2 small diesel generators generate electricity, which is in turn fed to electric propulsion motors which drive each propeller shaft. The diesel generators produce all the power required to run the ships facilities such as domestic power, A/C systems and the Galleys. The engine room is manned 24 hours a day, just like the bridge, by dedicated engineer watch keepers. The senior engineer mans the control room, monitoring the plant on the control screens, whilst the junior EOOW will be down in the engine room.
The Chart Pilot
Many modern cruise ships operate on a fully ECDIS (Electronic Chart Display and Information System) complaint system. The Chart Pilot system allows for the ship to be navigated without means of conventional paper charts. The Chart Pilot system allows for the ship to be navigated without the means of conventional paper charts. The Chart Pilot is part of the Integrated Bridge System which allows for the chart and radar to be monitored simultaneously.
The ship is steered from the bridge in either NACOS control, automatic or manual control modes. Repeaters from the gyro compass are located on the steering console, together with a magnetic compass read out situated above. The auto pilot is an adaptive unit; it is “intelligent” and learns about how the weather is affecting the ship. It is then able to use this intelligence to control the ships rudders to compensate for the effects of drift, caused by wind and currents. The auto pilot calculates the amount of rudder required for maintaining a set course, this signal is then fed to the ships steering motors which in turn operate the rudders. Rudder angle indicators are located on the steering console and also on both bridge wings, allowing the bridge team to see the required degrees of rudder to apply during manoeuvre. A rate of turn indicator is also included on the steering console and is repeated on the bridge wings – this allows the bridge team to monitor the rate at which the ships course is changing in degrees per minute.
NACOS Navigation System
The NACOS (Navigation and Command System) is made up og a group of integrated navigational systems which can automatically guide the ship, adapting to weather and current on pre-planned courses and tracks. The track control takes into account wind, set and drift, ensuring the ship follows her set track, constantly correcting herself under the supervision of the Officer of the Watch. The system is also able to follow a detailed time table by controlling the propulsion system.
Each cruise ship has several primary radars. In the case of Emerald Princess she has 3 scanners mounted on the main navigation mast, one scanner mounted on her bow and one at her stern. These all have a function fitted known as ARPA – Automatic Radar Plotting Aid, this allows the navigational officers to “acquire a target” and find out all the relevant information to avoid collision, including bearing, speed, course, CPA (closest point of approach) and TCPA (time to closest point of approach).
I hope you have learned something new and interesting by reading this today! 🙂 All cruise ships operate in a similar way, but I would like to thank Princess Cruises specifically for providing all of the info contained within today’s blog!
Images featured are of several different cruise ships.