1 GENERAL
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1580 – Guidelines for Vessels and Units with Dynamic Positioning (DP) Systems – (16 June 2017) - Annex - Guidelines for Vessels and Units with Dynamic Positioning (DP) Systems - 1 GENERAL

1 GENERAL

 1.1 Purpose

The purpose of these Guidelines is to recommend the design criteria, equipment, operating provisions and testing as well as a documentation regime for dynamic positioning systems in order to reduce the risk to the personnel, the vessel, other vessels or structures, sub-sea installations and the environment, while performing operations under dynamic positioning control.

1.2 Definitions

For the purpose of these Guidelines, unless expressly provided otherwise, the terms used herein are defined hereunder:

1.2.1 Activity-Specific Operating Guidelines (ASOG) means guidelines on the operational, environmental and equipment performance limits for the location and specific activity. (For drilling operations, the ASOG may be known as the Well-Specific Operating Guidelines (WSOG)).

1.2.2 Bus-tie breaker means a device connecting/disconnecting switchboard sections ("closed bus-tie(s)" means connected).

1.2.3 Company means the owner of the ship or any other organization or person such as the manager, or the bareboat charterer, who has assumed the responsibility for operation of the ship from the owner of the ship and who on assuming such responsibility has agreed to take over all duties and responsibilities imposed by the International Safety Management Code.

1.2.4 Computer system means a system consisting of one or more computers and associated hardware, software and their interfaces.

1.2.5 Consequence analysis means a software function continuously verifying that the vessel will remain in position even if the worst-case failure occurs.

1.2.6 Dynamic Positioning control station (DP control station) means a workstation designated for DP operations, where necessary information sources, such as indicators, displays, alarm panels, control panels and internal communication systems are installed (this includes: DP control and independent joystick control operator stations, required position reference systems' Human Machine Interface (HMI), manual thruster levers, mode change systems, thruster emergency stops, internal communications).

1.2.7 Dynamic Positioning operation (DP operation) means using the DP system to control at least two degrees of freedom in the horizontal plane automatically.

1.2.8 Dynamic Positioning Verification Acceptance Document (DPVAD) means the document issued by the Administration or its Recognized Organization to a DP vessel complying with these Guidelines. (See appendix for model form.)

1.2.9 Dynamically positioned vessel (DP vessel) means a unit or a vessel which automatically maintains its position and/or heading (fixed location, relative location or predetermined track) by means of thruster force.

1.2.10 Dynamic Positioning control system (DP control system) means all control components and systems, hardware and software necessary to dynamically position the vessel. The DP control system consists of the following:

  • .1 computer system/joystick system;

  • .2 sensor system(s);

  • .3 control stations and display system (operator panels);

  • .4 position reference system(s);

  • .5 associated cabling and cable routeing; and

  • .6 networks.

1.2.11 Dynamic Positioning system (DP system) means the complete installation necessary for dynamically positioning a vessel comprising, but not limited to, the following sub-systems:

  • .1 power system;

  • .2 thruster system; and

  • .3 DP control system.

1.2.12 Failure means an occurrence in a component or system that causes one or both of the following effects:

  • .1 loss of component or system function; and/or

  • .2 deterioration of functional capability to such an extent that the safety of the vessel, personnel or environment protection is significantly reduced.

1.2.13 Failure Modes and Effects Analysis (FMEA) means a systematic analysis of systems and sub-systems to a level of detail that identifies all potential failure modes down to the appropriate sub-system level and their consequences.

1.2.14 FMEA proving trials means the test program for verifying the FMEA.

1.2.15 Hidden failure means a failure that is not immediately evident to operations or maintenance personnel and has the potential for failure of equipment to perform an on-demand function, such as protective functions in power plants and switchboards, standby equipment, backup power supplies or lack of capacity or performance.

1.2.16 Joystick system means a system with centralized manual position control and manual or automatic heading control.

1.2.17 Loss of position and/or heading means that the vessel's position and/or heading is outside the limits set for carrying out the DP activity in progress.

1.2.18 Position keeping means maintaining a desired position and/or heading or track within the normal excursions of the control system and the defined environmental conditions (e.g. wind, waves, current, etc.).

1.2.19 Power management system means a system that ensures continuity of electrical supply under all operating conditions.

1.2.20 Power system means all components and systems necessary to supply the DP system with power. The power system includes but is not limited to:

  • .1 prime movers with necessary auxiliary systems including piping, fuel, cooling, pre-lubrication and lubrication, hydraulic, pre-heating, and pneumatic systems;

  • .2 generators;

  • .3 switchboards;

  • .4 distribution systems (cabling and cable routeing);

  • .5 power supplies, including uninterruptible power supplies (UPS); and

  • .6 power management system(s) (as appropriate).

1.2.21 Redundancy means the ability of a component or system to maintain or restore its function when a single failure has occurred. Redundancy can be achieved, for instance, by the installation of multiple components, systems or alternative means of performing a function.

1.2.22 Time to safely terminate (operations) means the amount of time required in an emergency to safely cease operations of the DP vessel.

1.2.23 Thruster system means all components and systems necessary to supply the DP system with thrust force and direction. The thruster system includes:

  • .1 thrusters with drive units and necessary auxiliary systems including piping, cooling, hydraulic, and lubrication systems, etc.;

  • .2 main propellers and rudders if these are under the control of the DP system;

  • .3 thruster control system(s);

  • .4 manual thruster controls; and

  • .5 associated cabling and cable routeing.

1.2.24 Worst-Case Failure Design Intent (WCFDI) means the specified minimum DP system capabilities to be maintained following the worst-case failure. The worst-case failure design intent is used as the basis of the design. This usually relates to the number of thrusters and generators that can simultaneously fail.

1.2.25 Worst-Case Failure (WCF) means the identified single fault in the DP system resulting in maximum detrimental effect on DP capability as determined through the FMEA.

Parent topic: Annex - Guidelines for Vessels and Units with Dynamic Positioning (DP) Systems
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