- CONNING DISPLAY
- MAGNETIC COMPASS
- SPEED LOG
- WIND SENSOR
- WEATHER FAX
Marine radars are X band or S band radars on ships, used to detect other ships and land obstacles, to provide bearing and istance for collision avoidance and navigation at sea. They are electronic navigation instruments that use a rotating antenna to sweep a narrow beam of microwaves around the water surface surrounding the ship to the horizon, detecting targets by microwaves reflected from them, generating a picture of the ship’s surroundings on a display screen.
Radar is a vital navigation component for safety at sea and near the shore. Captains need to be able to maneuver their ships within feet in the worst of conditions and to be able to navigate “blind”, when there is no visibility at night or due to bad weather. In addition to vessel-based marine radars, in port or in harbour, shore-based vessel traffic service radar systems are used by harbormasters and coast guard to monitor and regulate ship movements in busy waters.
Radars are rarely used alone in a marine setting. A modern trend is the integration of radar with other navigation displays on a single screen, as it becomes quite distracting to look at several different screens. Therefore, displays can often overlay an electronic GPS navigation chart of ship position, and a sonar display, on the radar display. This provides a combined view of surroundings, to maneuver the ship.
In commercial ships, radars are integrated into a full suite of marine instruments including chartplotters, sonar, two-way marine radio, satellite navigation (GNSS) receivers such as the US Global Positioning System (GPS), and emergency locators (SART). With digital data buses to exchange data, these devices advanced greatly in the early 21st century. For example, some have 3D displays that allow navigators to see above, below and all around the ship, including overlays of satellite imaging.
An Electronic Chart Display and Information System (ECDIS) is a computer-based navigation system that complies with IMO regulations and can be used as an alternative to paper navigation charts. Integrating a variety of real-time information, it is an automated decision aid capable of continuously determining a vessel’s position in relation to land, charted objects, navigation aids and unseen hazards.
An ECDIS includes electronic navigational charts (ENC) and integrates position information from the Global Positioning System (GPS) and other navigational sensors, such as radar, fathometer and automatic identification systems (AIS). It may also display additional navigation-related information, such as sailing directions.
It is a screen based information system. Sensor input data and corresponding orders (set points) collected from individual sensors and instruments are logically grouped and presented on a screen for easy viewing from the primary workstations up to a distance of 2 meters from the screen. The conning information display system uses graphic display technique and locates the data inputs appropriately around and on a symbol illustrating the configuration of the ship. Bridge and watch alarm system is available as an integrated function of the conning display, with clear alarm message display and acknowledgment functions at every conning display. Conning Display provides the information required for safe navigation and maneuvering from one central location.
Conning Display is a screen based information system and is available for any type of vessel. The data is presented in clear and efficient format, minimizing human errors.
Conning Display is designed according to NAUT – OSV requirements for Conning Display.
The design of Conning Display is configurable, and can be set according to owner’s choice and preferences.
STATUS INFORMATION DISPLAYED
- Rudder angle
- Speed forward and stern as well as athwart ship if applicable depending on the log system
- Thruster pitch
- Main propeller RPM and pitch
- Water depth
- True and relative wind speed and direction
ROUTE AND DATA DISPLAYED
- Bearing to wheel over position (WOP)
- Distance and time to WOP
- Off track error and limit
- Position receiver status
- Track steering work station in command
- Autopilot modes
- Estimated time of arrival
An autopilot is an electronic device permitting the vessel to automatically maintain a set heading without need to tend the helm. Once a course is entered, the autopilot will maintain it by automatically adjusting the rudder.
Connecting the device to bridge instruments such as electronic charts, radar, gyrocompass or GPS, may offer multiple self-steering options, such as “track” or “heading” modes.
The autopilot is usually connected to two devices: the gyrocompass, which continuously registers the heading, and the servomotor, which actually performs the rudder alterations. Malfunction of the gyrocompass or the servomotor may cause malfunction of the autopilot.
Selection of an autopilot depends on its compatibility with other bridge devices.
Autopilot is the use of an automatic system to control the rudder on the vessel. Use of autopilot can reduce the fuel consumption by smoothing out the large angle rudder movements used to hold a steady course. Efficient and adaptive autopilot operations allow small deviations to course-line, but will use fewer and smaller angle rudder movements to maintain the course-line. This decreases the rudder movement and consequently reduces fuel consumption.
The Global Positioning System (GPS) has changed the way the world operates. This is especially true for marine operations, including search and rescue. GPS provides the fastest and most accurate method for mariners to navigate, measure speed, and determine location. This enables increased levels of safety and efficiency for mariners worldwide.
It is important in marine navigation for the ship’s officer to know the vessel’s position while in open sea and also in congested harbors and waterways. While at sea, accurate position, speed, and heading are needed to ensure the vessel reaches its destination in the safest, most economical and timely fashion that conditions will permit. The need for accurate position information becomes even more critical as the vessel departs from or arrives in port. Vessel traffic and other waterway hazards make maneuvering more difficult, and the risk of accidents becomes greater.
Governments and industrial organizations around the world are working together to develop performance standards for Electronic Chart Display and Information Systems, which use GPS and/or DGPS for positioning information. These systems are revolutionizing marine navigation and are leading to the replacement of paper nautical charts. With DGPS, position and radar information can be integrated and displayed on an electronic chart, forming the basis of the Integrated Bridge System which is being installed on commercial vessels of all types.
GPS information is embedded within a system known as the Automatic Identification System (AIS) transmission. The AIS, which is endorsed by the International Maritime Organization, is used for vessel traffic control around busy seaways. This service is not only vital for navigation, but is increasingly used to bolster the security of ports and waterways by providing governments with greater situational awareness of commercial vessels and their cargo.
A Gyro compass is a form of gyroscope, used widely on ships employing an electrically powered, fast-spinning gyroscope wheel and frictional forces among other factors utilising the basic physical laws, influences of gravity and the Earth’s rotation to find the true north.
Gyro compass has become one indispensable instrument in almost all merchant ships or naval vessels for its ability to detect the direction of true north and not the magnetic north. It is comprised of the following units:
a. Master Compass: Discovers and maintains the true north reading with the help of gyroscope.
b. Repeater Compasses: Receive and indicate the true direction transmitted electrically from the Master Compass.
c. Course Recorder: Makes a continuous record of the manoeuvring on a moving strip of paper.
d. Control Panel: Governs the electrical operation of the system and ascertains the running condition by means of a suitable meter.
e. Voltage Regulator: Maintains constant supply of the ship to the motor-generator.
f. Alarm Unit: Indicates failure of the ship’s supply.
g. Amplifier Panel: Controls the follow-up system.
h. Motor Generator: Converts the ship’s DC supply to AC and energizes the Compass equipment
Modern ships have access to many types of compasses. The GPS system can determine in which direction a ship is heading by comparing current position with a previous one. This is done continuously and, so long as the GPS signal is not being manipulated or faulty, should be sufficient.
Today all ships are required to have GPS installed but in addition they also require two other compasses: the traditional magnetic compass and a gyrocompass. A magnetic compass is of course only able to indicate magnetic North which is not a fixed point and local geo-magnetic conditions can cause the compass to be in error, as can the metallic structure of the ship itself (especially if there have been changes to the superstructure or after drydockings) or the cargo the ship is carrying.
All vessels should have their compass swung/adjusted and a new deviation card issued at maximum two-yearly intervals. When a new vessel is commissioned, compass deviation on any heading should be no more than 3°. Thereafter, deviation on any heading should be 5° or less. Vessels transiting the Panama Canal are required by the canal authorities to have had a valid compass deviation card issued within the previous 12 months. Some flag states and many shipowners will stipulate that the magnetic compass is to be swung and adjusted annually.
One of the dangers faced by a ship is that of running aground. Usually, a vessel determines its position by means of GPS, Radar, Decca, Loran or visual bearings. The depth of water is checked from the echo sounder just as a matter of routine to see that the depth obtained matches with that show on the chart. However when the position is not accurately known while approaching the port, or crossing over a bar, or near the mouth of a river, or in a poorly surveyed area, the under-keel clearance and depth of water needs to be known. The echo sounder comes in handy in such situation.
An Echo Sounder is a type of SONAR (Sound Navigation And Ranging) device used to determine the depth of water by transmitting sound pulses into water.
It works on the principle of transmitting sound waves from ship’s bottom and then measuring the time taken for the echo to be returned from sea. If the velocity of sound in water is known the time will be proportional to the distance travelled.
Echo sounding is a type of sonar used to determine the depth of water by transmitting sound waves into water. The time interval between emission and return of a pulse is recorded, which is used to determine the depth of water along with the speed of sound in water at the time. This information is then typically used for navigation purposes or in order to obtain depths for charting purposes.
Speed logs, also known as ship logs, chip logs, or common logs, measure the speed of a vessel. The speed is determined with reference to water flowing by the hull (water reference speed) or to the seabed (ground reference speed).
Ships of 50,000 GT or more and passenger vessels of 300 GT or more built after July 1, 2014, are required by SOLAS regulation to possess devices indicating both water reference and ground reference speed.
Mariners utilize a variety of technologies to determine the vessel’s rate of motion, including:
Electromagnetic — These devices, also called EM logs, rely on a coil in an electromagnetic sensor. When the AC current energizes the coil, it creates a magnetic field surrounding the sensor. As a vessel moves through water, an electrical field running perpendicular to the magnetic field is produced. The sensor electrodes detect and deliver the resulting signal representing the ship’s speed to a preamplifier, which then converts it to a digital format for viewing. This process is inexpensive and has the advantage of not requiring any moving parts. However, water salinity and temperature can affect calibration. The water flow slows down closer to the hull due to friction, affecting measurements.
Pitometer — Also referred to as a pit log, the instrument uses the principle of differential pressure to determine an object’s speed through the water. It operates by submerging a Pitot tube with an opening at the base in water. While the tube is stationary, the pressure (known as static pressure) remains constant. When the tube starts moving past the water, it creates dynamic water pressure that varies based on the velocity. The effect of static pressure is removed to obtain an accurate measurement of the dynamic pressure for calculating the speed. To achieve this, a second tube is installed near the first with an equivalent static pressure. Movement through water does not generate any dynamic pressure in the second tube. The difference between the pure dynamic and static pressure readings indicates the speed of the moving object.
Doppler — Doppler transducers rely on the Doppler frequency shift effect for estimating the speed of a moving body. A transducer produces high-frequency sound pulses toward both ends of a vessel using two transmitter windows. The reflected pulses are detected by two receiver windows located in the transducer. The time delay between the transmitted signals confirms the receipt of echoes from undisturbed water surrounding the object. The vessel’s fore/aft speed vector is estimated by processing the signal information. A pre-amplifier then transmits this information in a digital format.
GPS (Global Positioning System) — A sensor accesses the GPS satellite signals to pinpoint an object’s speed, in both longitudinal and transverse directions. GPS receivers with integrated rate gyros and an antenna unit calculate the heading velocity, attitude, and course. The heading is then compared in relation to the vessel’s magnitude and direction of motion in the water. Information delivered by the satellites is processed by the system, integrating the velocity data with the longitudinal and transverse ground speeds of the vessel. Speed vectors combined with data related to the rate-of-turn assist in differentiating between the vessel’s translational and rotational movement. These are required for estimating the transverse speeds for both bow and stern as given on the docking display.
NAVTEX, an acronym for navigational telex (navigational text messages) is a device used on-board the vessels to provide short range Maritime Safety Information in coastal waters automatically. It can be used in ships of all types and sizes. The area covered by Navtex can extend as far as 400 nautical miles from the broadcast station. A NAVTEX receiver on board prints out navigational and meteorological warnings and forecasts as well as urgent Marine Safety Information to ships. It forms a vital element of the Global Maritime Distress Safety System (GMDSS). Navtex uses the feature of radio telex or Narrow Band Direct Printing (NBDP) for the automatic broadcast of information.
The automatic identification system (AIS) is an automatic tracking system that uses transponders on ships and is used by vessel traffic services (VTS). When satellites are used to detect AIS signatures, the term Satellite-AIS (S-AIS) is used. AIS information supplements marine radar, which continues to be the primary method of collision avoidance for water transport.
Information provided by AIS equipment, such as unique identification, position, course, and speed, can be displayed on a screen or an electronic chart display and information system (ECDIS). AIS is intended to assist a vessel’s watchstanding officers and allow maritime authorities to track and monitor vessel movements. AIS integrates a standardized VHF transceiver with a positioning system such as a Global Positioning System receiver, with other electronic navigation sensors, such as a gyrocompass or rate of turn indicator. Vessels fitted with AIS transceivers can be tracked by AIS base stations located along coast lines or, when out of range of terrestrial networks, through a growing number of satellites that are fitted with special AIS receivers which are capable of deconflicting a large number of signatures.
The International Maritime Organization’s International Convention for the Safety of Life at Sea requires AIS to be fitted aboard international voyaging ships with 300 or more gross tonnage (GT), and all passenger ships regardless of size.
Bridge Navigational Watch & Alarm System – BNWAS is a monitoring and Alarm system which notifies other navigational officers or master of the ship if the officer on watch (OOW) does not respond or he/she is incapable of performing the watch duties efficiently, which can lead to maritime accidents.
The purpose of a bridge navigational watch alarm system (BNWAS) is to monitor bridge activity and detect operator disability which could lead to marine accidents. The system monitors the awareness of the Officer of the Watch (OOW) and automatically alerts the Master or another qualified OOW if for any reason the OOW becomes incapable of performing the OOWís duties. This is achieved through a mix of alarms and indications which alert backup OOWs as well as the Master. BNWAS warnings are given in the case of incapacity of the watchkeeping officer due to accident, sickness or in the event of a security breach, e.g. piracy and/or hijacking. Unless decided by the Master only, the BNWAS shall remain operational at all times.
Voyage data recorder, or VDR, is a data recording system designed for all vessels required to comply with the IMO’s International Convention SOLAS Requirements (IMO Res.A.861(20)) in order to collect data from various sensors on board the vessel. It then digitizes, compresses and stores this information in an externally mounted protective storage unit. The protective storage unit is a tamper-proof unit designed to withstand the extreme shock, impact, pressure and heat, which could be associated with a marine incident (fire, explosion, collision, sinking, etc.).
The protective storage unit may be in a retrievable fixed unit or free float unit (or combined with EPIRB) when the ship sinks in a marine accident. The last 12 hours (48 Hours for the 2014 regulations MSC.333(90)) of stored data in the protected unit can be recovered and replayed by the authorities or ship owners for incident investigation. Besides the protective storage unit, the VDR system may consist of a recording control unit and a data acquisition unit, which are connected to various equipment and sensors on board a ship. The new MSC.333(90) regulations also state a minimum of 30 days of recorded data must be held internally (this could be within the recording control unit, data acquisition unit, Main Electronics Unit depending on the manufacturers terminology).
Although the primary purpose of the VDR is for accident investigation after the fact, there can be other uses of recorded data for preventive maintenance, performance efficiency monitoring, heavy weather damage analysis, accident avoidance and training purposes to improve safety and reduce running costs.
Simplified voyage data recorder (S-VDR), as defined by the requirements of IMO Performance Standard MSC.163(78), is a lower cost simplified version VDR for small ships with only basic ship’s data recorded.
The information recorded in the unit(s) (sometimes also called the ship’s black box) may include the following information:
a. Position, date, time using GPS
b. Speed log – Speed through water or speed over ground
c. Gyro compass – Heading
d. Radar – As displayed or AIS data if no off-the-shelf converter available for the Radar video
e. ECDIS – A screen capture every 15 seconds and a list of navigational charts in use every 10 minutes or when a chart change occurs
f. Audio from the bridge, including bridge wings
g. VHF radio communications
h. Echo sounder – Depth under keel
ı. Main alarms – All IMO mandatory alarms
i. Hull openings – Status of hull doors as indicated on the bridge
j. Watertight & fire doors status as indicated on the bridge
k. Hull stress – Accelerations and hull stresses
l. Rudder – Order and feedback response
m. Engine/Propeller – Order and feedback response
n. Thrusters – Status, direction, amount of thrust % or RPM
o. Anemometer and weather vane – Wind speed and direction
Regulations require that ships record weather data including wind speed, with the data displayed continuously on the ship bridge. The ship’s captain is able to use this data to navigate around storms, increasing safety for passengers and crew.
Facsimile (fax) is a means of providing weather information to ships at sea. The information is presented as a chart (map), showing barometric high pressures, low pressures, pressure gradients, wind speed and direction, and temperature.
Schedules for facsimile weather broadcast were provided in marine publications and could also be sent via facsimile.
The Ship Security Alert System (SSAS) is a safety measure for strengthening ship’s security and subduing acts of piracy and/or terrorism against shipping. Widely Acknowledged as a part of the International Ship and Port Facility Security Code (ISPS code), the Ship Security Alert System (SSAS) complements the International Maritime Organization (IMO)’s attempts to increase maritime vessel security.
Cospas-Sarsat, with International Maritime Organization’s cooperation, came up with this project of Ship Security Alert System (SSAS). The basic idea is that in case of an attempted piracy effort, terrorist act, or any other incident which can be defined as a threat to the ship under the maritime security, the ship’s SSAS beacon would be activated, responding to which an appropriate law-enforcement or military forces would be dispatched for rescue. The Ship Security Alert System (SSAS) beacon and the Aircraft Transponder Emergency Code 7700 are operated on the fundament of similar principles.
The SSAS is a type of silent ship security alarm system which, when activated, does not issue any audio-visual signal on the ship or to nearby vessels or security forces. The alert in most cases is first received by the ship’s owner or an SSAS management third party, then passed to the ship’s flag state, and these receivers are obliged to inform the national authorities of the coastal states where the ship is sailing.
The Flag States decide who will be the initial recipient of the security alerts from the ships. The recipient may be one or more parties designated by the Flag State as competent authorities, which may include the Company (shipowner) or a SSAS manaegement third party.