MARH027 — Apply knowledge of dynamic positioning systems

Elements & performance criteria

Performance evidence

• describing operational advantages and disadvantages of Artemis position referencing system and acoustic systems for dynamic positioning
• describing the architecture of a typical dynamic positioning control system
• describing the different principles of position referencing systems and how they are used in dynamic positioning installations
• describing the reasons for discrepancy between the displayed value of dynamic positioning current/sea force, the dynamic positioning system and the true current/tidal stream value
• describing the use of external force reference systems, including hawser tension, plough cable tension and pipe tension monitoring
• determining the sources of error and inaccuracy associated with differential global navigation satellite system (DGNSS)
• identifying and explaining the function of control computers, input/output (I/O) devices, network connections and operator stations
• identifying the quality of available data to an operator associated with DGNSS
• outlining advantages and disadvantages of the taut wire position referencing systems
• outlining advantages and limitations of DGNSS, laser-based position referencing system and frequency-modulated continuous wave (FMCW) radar-based position referencing system
• outlining the different types of position referencing systems used in dynamic positioning installations
• outlining the operational advantages and limitations of the Artemis position referencing system

Knowledge evidence

• control system – computers/control elements/networks and man/machine interface (MMI), including:
• achieving redundancy as described in International Maritime Organization (IMO) MSC Circ. 645 / 1580 and vessel FMEAs
• architecture of a typical dynamic positioning control system
• function of the following components: control computers, I/O devices, network connections, operator stations
• dynamic positioning sensors - environment and vessel – anemometers/gyro/motion reference unit (MRU), including:
• function of gyro compasses and their redundancy within a dynamic positioning system
• obtaining pitch, roll and heave information for input into a dynamic positioning system
• reason for inputting pitch, roll and heave into a dynamic positioning system
• environmental reference systems, including:
• limitations of wind sensor inputs
• reasons for and the consequences of deselecting wind sensor inputs
• method by which the dynamic positioning system determines the value for dynamic positioning current or sea force (the residual error resulting from unmeasured errors and unmeasured forces acting on the vessel)
• provision of wind sensors within the dynamic positioning system
• reasons for discrepancy between the displayed value of dynamic positioning current (or sea force) on the dynamic positioning system and the true current or tidal stream value
• wind feed-forward facility and its importance within the dynamic positioning system
• external force reference systems, including:
• the use of external force reference systems such as hawser tension, plough cable tension and pipe tension monitoring
• global navigation satellite system (GNSS), including:
• advantages and limitations of the DGNSS when compared with other position referencing systems
• available quality data associated with the DGNSS
• error and inaccuracy associated with the DGNSS, describing the effects on the quality of positioning.
• operation of a typical commercial DGNSS network where corrections are delivered by satellite communications
• principles of the DGNSS
• principles used in relative DGNSS
• position referencing systems, including:
• different types of position reference systems used in dynamic positioning installations
• different principals used in the operation of the above systems, including:
• GNSS, including:
• advantages and limitations of the DGNSS when compared with other position referencing systems
• available quality data associated with the DGNSS
• error and inaccuracy associated with the DGNSS and the effects on the quality of positioning
• operation of a typical commercial DGNSS network where corrections are delivered by satellite communications
• principles of the DGNSS
• principles used in relative DGNSS
• laser systems, including:
• advantages and limitations associated with a laser-based position referencing system
• method of setting up a laser system to provide best position information
• principles of position references using laser-based systems
• FMCW radar-based systems, including:
• advantages and limitations associated with FMCW radar-based position referencing systems
• operational advantages and limitations of the Artemis position referencing system
• principle and operation of the Artemis position referencing system principles of position reference using FMCW radar-based systems
• acoustic systems, including:
• layout of a typical hydro-acoustic system, including operator station, transceiver, transducer pole and transducer
• operation of hydro-acoustic position referencing systems
• operational advantages and limitations of acoustic systems as a position reference for dynamic positioning
• principles of position-fixing using underwater acoustic systems working in super-short baseline (SSBL)/ultra-short baseline (USBL) and long baseline (LBL) modes
• various types of hydro-acoustic beacon: transponder, responder and pinger/beacon
• other systems, including:
• advantages and limitations of the taut wire position reference systems
• different types of taut wire position reference system
• display of taut wire reference data in the dynamic positioning system
• principle of position reference using the taut wire system.
• principle of inertial navigation system (INS) and the methods of using INS to enhance existing position referencing system performance
• other position referencing systems that may be used in conjunction with a dynamic positioning system
• position reference handling, including:
• median rejection when three or more are used and the importance of monitoring the position reference page
• relative accuracy and reliability of position referencing systems, together with the methods used to apply weighting and pooling and voting when more than one position referencing system is used
• power development and power distribution, including:
• functions of a power management system as installed on Class 2 and Class 3 dynamic positioning vessels
• power generation and distribution arrangements in a typical diesel-electric dynamic positioning vessel, with particular reference to system redundancy as described in IMO MSC Circ. 645 and vessel FMEA
• power requirements of dynamic positioning vessels and the concept of available power and spinning reserve in worst case failure
• power supply and distribution arrangements in a typical hybrid diesel/diesel-electric dynamic positioning vessel (main controllable pitch propellers (CPP) or Az drive which are direct drive)
• provision of uninterruptible power supply (UPS) to the dynamic positioning system, with particular reference to power shortages, failures and system redundancy
• propulsion systems, including:
• azimuth thrusters
• azipod thrusters
• importance of monitoring the displayed values of set point and feedback data for thruster and propeller rpm, pitch and/or azimuth
• operational characteristics and common failure modes of the different types of propulsion systems as described above
• rudders
• tunnel thrusters: Voith Schneider, waterjet
• types of propulsion system commonly installed in dynamic positioning equipped vessels, including main propellers.

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