ABS Guide for Dynamic Positioning Systems

ABS SEMINAR: ABS GUIDE FOR DYNAMIC POSITIONING SYSTEMS

Sue WangSenior Managing Principal Engineer, Offshore

Singapore1 March 2013

2

Objective and Agenda

� Introduce ABS Guide for DP systems to industry

� Seek industry feedbacks and comments

� Part 1: Overview of

� DP system

� ABS Guide for DP systems

� Part 2: New optional Notations for

� Enhanced DP system (EHS)

� Station keeping performance (SKP)

3

up

to 7

0s

80

s

90

-95

96

-99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

up

Rapid Expansion of DP Demand

� Deep-water activity

� More complex field development

� Wider range of application

� Advancement of technology

4

Dynamic Positioning Applications

� MODUs (drillships and semisubmersibles)

� Offshore support, installation and maintenance vessels

� Pipe- and cable laying

� Dredging

� Offloading shuttle tankers

� Cruise ships, large motor yachts

� DP-assisted mooring

� FPSOs in deepwater

� Others

5

Basic DP Principles

� A dynamic positioning (DP) control system automatically calculates the forces that the thrusters, propulsors and steering gear must produce in order to control the vessel’s position and heading

� The DP control systems algorithm's will generate control signals to the thrusters, propulsors and steering gear to obtain the force and moment required for the requested position and heading control

6

What Do We Need for DP?

� Power

� Thrusters and rudders

� Position measurement

� Position filtering (LF)

� Control algorithm (positive required force)

� Thruster and rudder allocation

7

Elements of a DP System

7

DP Operator

Human-Machine

Interface

Computer

Operator Panel

Display Screen

DP Controller

(DPC)Power Syste

m

SensorsCompass

WindVertical Reference

DraftTension

Position Reference Systems (PRS)

DGPSUnderwater Acoustics

LaserMicrowaveTautwire

Thrusters

8

Typical DP System Layout

ControllerOperator

Station

Tunnel

Thruster

Azimuth

Thruster

Propulsion

Thruster

Rudder

Hardwire

or LAN

9

How DP System Work

VESSEL THRUST

EKF PID

Measured

Position

ALLOC

Wind

Waves

Current

(T,α)1..n

=

f(Fx, Fy, Mz)0 1 2 3 4 5 6 7 8 9 10

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

time/T0 [-]

X/X

0 [

-]

1+e(- βω

ot)

1-e(-βω

ot)

β = 0.1

β = 0.3

β = 0.5

β = 0.7

β = 1

β = 0.05

X0

10

Basic Elements DP Control System

Thrusters

Power, Sensors, Position References

11

Common Position Measurement Equipment

� Fan Beam (Laser Technique)

� Taut Wire (Vertical Angle)

� DGPS (Satellite)

� HPR (Long and Short Base, Hydro-acoustic, Transponders)

� Atriums (Radio Wave, Landmark, Specific-Site)

� Others

12

DP System Vendors

� Kongsberg Maritime

� Converteam (GE)

� L-3

� Marine Technologies

� Navis Engineering

� Rolls-Royce

� Nautronix

� Others

13

Basic Elements of a Power System

14

Thrusters & Rudders

� Main propellers

� Bow and stern thrusters

� Azimuthing thrusters

� Retractable thrusters

� Rudders

15

DP Guidelines from Related Organizations

� IMO MSC Circular 645

� IMO MODU Code

� ISO 19901-7 Stationkeeping

� US Coast Guard

� Norwegian Maritime Directorate (NMD)

� Flag State

� International Marine Contractors Association (IMCA)

� Marine Technology Society (MTS)

� American Petroleum Institute (API)

� Class Societies

16

IMO & ABS DP Equipment Class

� IMO Class 1

� For equipment class 1, loss of position may occur in the event of a

single fault

� ABS DPS-1

� For vessels which are fitted with a dynamic positioning system which

is capable of automatically maintaining the position and heading of

the vessel under specified maximum environmental conditions

having an independent centralized manual position control with

automatic heading control

17

IMO & ABS DP Equipment Class

� IMO Equipment Class 2

� A loss of position is not to occur in the event of a single fault in any

active component or system (generators, thrusters, switchboards,

remote controlled valves, etc.)

� Normally static components will not be considered to fail

� ABS DPS-2

� For vessels which are fitted with a dynamic positioning system which

is capable of automatically maintaining the position and heading of

the vessel within a specified operating envelope under specified

maximum environmental conditions during and following any single

fault, excluding a loss of compartment or compartments

18

IMO & ABS DP Equipment Class

� IMO Class 3

� For equipment Class 3, a single failure includes items listed previous

for Class 2, and any normally static component is assumed to fail

� All components in any watertight and fire protected compartment

� ABS DPS-3

� For vessels which are fitted with a dynamic positioning system which

is capable of automatically maintaining the position and heading of

the vessel within a specified operating envelope under specified

maximum environmental conditions during and following any single

fault, including complete loss of a compartment due to fire or flood

19

Selection of DP Equipment Class

� DP equipment class governed by the type of operations

� Norwegian Maritime Directorate (NMD) has specified

� DP units of Class 1 should be used during operations where loss of

position is not considered to endanger human lives, cause significant

damage or cause more than minimal pollution

� DP units of Class 2 should be used during operations where loss of

position could cause personnel injury, pollution or damage with great

economic consequences

� DP units of Class 3 should be used during operations where loss of

position could cause fatal accidents, severe pollution or damage with

major economic consequences

20

Guidelines for DP Equipment Class

Operation NORSOK MTSOne Oil

CompanyRemark

Drilling 3 2 32

Diving inside structures 3 2 3

Diving in open water 2 2 3

Pipelay/umbilical lay 2 2 33

Lifting 2 2 3

Shuttle Offtake 2 2 2

ROV Support (Open water) 1

ROV Support (Close Proximity - Surface/Subsea) 2 2 2

Floating Production (HC production) 3 2

Well intervention 2 21

32

Logistics Operations 21

2

Subsea well workover 3 32

Accomodation (ganway connection to installation) 3 2 3

Accomodation (outside 500m safety zone) 2

Construction activies inside 500m general 2 2

Construction activies outside 500m general 1

1 Vessels of lesser Class may be

used with the appropriate

structured risk identification and

mitigation measures in place

2 Class 2 acceptable with extra fire

watch and engine control watch

routines

3 Class 3 for Norwegian

Continental Shelf. For others, Class

2 accetable with Extra fire watch

and engine control watch routines

USCG: Class 2 or above for MODU

according to IMO MODU Code

21

ABS DPS Rules & Guides & Notations

� ABS Guide for Thrusters and Dynamic Positioning System (1994) was incorporated in the Rules for Building and Classing Steel Vessels, 4-3-5/15 in 2000

� ABS Guide for Dynamic Positioning Systems (December 2012)

� DPS Basic Notations

� DPS-0, DPS-1, DPS-2, DPS-3

� Inline with IMO Guidelines for Vessels with Dynamic Positioning

Systems (1994)

� Supplement Notations

� EHS-P, EHS-C, EHS-F

� SKP, SKP(a,b,c,d,e,f)

� Incorporate new development

� Provide flexibility

22

DPS Notations

� Notation DPS-0

� Most basic system

� No redundancy

� Centralized manual position control with automatic heading control

(joystick)

� Notation DPS-1

� No redundancy

� One automatic position and heading control computer

� Independent manual position control with automatic heading control

(joystick)

23

DPS Notations

� Notation DPS-2

� Redundancy design and able to maintain position and heading with

a single fault

� Redundant(2) automatic position and heading control computers

� Independent manual position control with automatic heading control

(joystick)

� Notation DPS-3

� Redundancy design with physical separation and able to maintain

position and heading with a single fault and loss of a compartment

due to fire or flood

� Redundant(3) automatic position and heading control computers

� Independent manual position control with automatic heading control

(joystick)

24

Dynamic Positioning Systems

Items DPS Notation

0 1 2 3

Power System No Redundancy No Redundancy Redundancy Redundancy

Power management No No Yes Yes

UPS No Yes Yes Yes

Thruster System No Redundancy No Redundancy Redundancy Redundancy Automatic Control Computers

0 1 2 3

Manual Position Control with Auto heading

1 1 1 1

Manual Independent Thruster Control at Bridge

Yes Yes Yes Yes

Position Reference 1 2 3 3

Gyro Compass 1 2 3 3

MRU 0 2 3 3 Wind Sensors 1 2 3 3

Consequence Analyzer

No No Yes Yes

FMEA No No Yes Yes

25

Other ABS Rules Related to DP Components

� ABS Steel Vessels Rules� Diesel Engines – Section 4-2-1� Gas Turbines – Section 4-2-3� Electric Motors and Motor Controllers – Section 4-8-3� Gears – Section 4-3-1� Shafting – Section 4-3-2 � Propellers – Section 4-3-3� Piping System – Chapter 4-6 � Thrusters 4-3-5� Control Equipment and Systems – Section 4-9-7

� ABS MODU Rules� Pumps and Piping Systems – Chapter 4-2� Electrical Installation – Chapter 4-3� Rules for Equipment and Machinery Certification – Part 6� Surveys – Part 7

� ABS Rules for Survey After Construction� Machinery Surveys – Chapter 7-6� Shipboard Automatic and Remote-control Systems – Chapter 7-8� Survey Requirements for Additional Systems and Services – Chapter 7-9

26

Guide Development Background

� ABS updating Rules as routine process

� Industry demanding

� Wide range application of DP systems

� Flexibility

� Stationkeeping performance

� Reflect industry advancement

� Robust redundancy design concept

� Enhanced generator protection technology

� Rapid automatic blackout recovery

27

Innovation & New Technology

� Robust redundancy concept

� Advanced computing technology

� Enhanced FMEA process

� Advancement of sensor technology

� Advanced generator protection

� Advanced thruster control and protection

� Quick black-out recovery

� Comprehensive operation monitoring

27

28

Gap Analysis

� Level of details

� Lack of specifications

� Closed bus design

� Criteria for stationkeeping performance

� Enhanced features

� Advanced generator protection and control

� Blackout prevention and automatic quick recovery

� Robust redundancy concept

� Fire and flood protection of machinery space (for DPS-2)

� Higher availability and reliability of position reference systems

and sensors

29

Overview DPS Guide Development

� Major update for current ABS DPS Notations

� DPS-1

� DPS-2

� DPS-3

� Development of new optional notations

� DP system enhancement notation (EHS)

� Stationkeeping performance notation (SKP)

� Objective

� Reflect Industry advancement

� Provide flexibility

� Encourage higher design standards and consistent assessment

30

Highlight of DPS Guide

� Definitions to form a common basis of understanding

� Requirements on documentations for quality and completeness

� Increased level of details on technical requirements

� New enhanced system notations (EHS)

� Recognition of design features beyond DPS-series notations

� Encourage higher safe design standard

� Provide flexibility to owners and operators

� New stationkeeping performance notation (SKP)

� Recognition of DP capability

� Encourage robust design and consistent assessment

� Increased level of details on testing

� Vessel type and activity specifics

31

Content of DPS Guide

� General

� DP System Design

� Power System

� Thruster System

� Control System

� Marine Auxiliary System

� Initial Test of DP System

� Enhanced DP System

� Stationkeeping Performance

� Specific Vessel Types

� Other Optional DP System Notations

32

Section 1-3: Definitions

� Specified maximum environmental condition

� Specified operating envelope

� Single fault

� Dynamically positioned vessel

� Dynamic positioning system

� Industry mission

� Power system

� Thruster system

� DP control system

� Position reference system

� Joystick system

� Static component

� Active component

� Worst case failure

� Worst case failure design intent

� Consequence analysis

� DP capability analysis

� Redundancy concept

� Critical redundancy

� Redundant groups

� Autonomous system

� Closed bus

� Common mod failure

� Single fault tolerance

� Independence

� Loss of position

� Stationkeeping

33

Section 1-4: Documentations

� List of documentation (level of detail)

� Dynamic positioning system

� Power system

� Thruster system

� DP control system

� Documentation type (level of detail)

� R: Documentation for review

� I: Documentation for information and verification for consistency with

related review

� OB: Documentation needs to be kept onboard

� Added documents

� Basic design of DP system redundancy (R DPS-2 and DPS-3)

� Planned inspection and maintenance (I)

34

Section 2: Dynamic Positioning System Design

� 1 General

� 3 DP System Technical Requirements� 3.1 Basic requirement� 3.3 Redundancy design� 3.5 Physical separation � 3.7 DP system equipment requirements� 3.9 Stationkeeping performance

� 5 Essential non-DP Systems� 5.1 General� 5.2 Emergency shut down system and DP redundancy� 5.3 Fire protection and DP redundancy� 5.4 Fuel quick closing valves and DP redundancy

� 7 Alarms and Instrumentation

� 9 Communications and DP Alter System� 9.1 Communications� 9.2 DP alter system

� 11 Failure Mode and Effects Analysis� 11.1 Failure mode analysis� 11.2 FMEA report

� 13 DP Operations Manual

35

Section 2: Dynamic Positioning System Design

� Increased level of details for easy use

� Content of documents

� FMEA

– Failure modes

– FMEA analysis report

– FMEA proving trial report

� DP Operations Manual

� Stationkeeping performance analysis

� FMEA and Proving Trial Report (OB)

� After completion of DP proving sea trials, the final version of DP FMEA and

DP proving trial report, including final analysis and conclusions based on

actual results from DP testing, are to be submitted

� Updated after major modifications

36

Section 3: Power System

� 1 General

� 3 Power Generation System

� 5 Power Distribution System

� 7 Power Management System

� 9 Uninterruptible Power Systems (UPS)

37

Section 3: Power System

� Level of details for easy use

� Closed bus tie breaker (DPS-2 and DPS-3)

� Capable of breaking the maximum short circuit current in the

combined system

� Coordinated in relation to generator breakers to avoid total loss of

main power (blackout)

� Two bus tie breakers are to be provided between bus sections

� Closed bus for DPS-3

� Consideration of EHS-P requirements

� If all thrusters are direct diesel drive, no need for a power management system

38

Section 4: Thruster System

� 1 General

� 3 Thruster Capacity

� 5 Thruster Configuration

� 7 Thruster Auxiliary System

� 9 Thruster Control

� 11 Thruster Monitoring and Alarm

� Level of details for easy use

39

Section 5: DP Control System

� 1 General

� 3 DP Control Station

� 5 DP Control System

� 7 Manual Position Control System

� 9 Control Mode Selection

� 11 Position Reference System and Environment Sensor

� 13 Consequence Analysis (For DPS-2/3)

� 15 Display and Monitoring

� Level of details for easy use

40

Section 5: DP Control System

� DP Control Station

� Main DP control station with good viewing of the external surrounding area

and all activities relevant to the DP operation

� Backup DP control station, a night vision, closed-circuit TV (CCTV) system

is acceptable for viewing the external surrounding area

� Data Communication Networks

� Communication network for DP control system is to be duplicated for

DPS-2 and also separated for DPS-3

� Manual position control system is not to share the same communication

network with the DP control system

� Control Mode Selection

� Easy operational device to be provided in the DP control station for the

selection of the thruster control modes

� Transfer of control to the backup DP control station to be initiated at backup

control station and performed manually

41

Section 5/11: Position Reference System & Wind Sensor

� One set of position reference system

� GPS (others, position measurement devices)

� Gyro (heading measurement device)

� MRU (others, roll and pitch measurement for position correction)

� MRU: where position reference systems are dependent on correction of roll and pitch effect, MRU or equivalent is to be provided

� Position reference systems and wind sensors to be powered by UPSs and follow group redundancy concept

42

Section 6: Marine Auxiliary System (DPS 2/3)

� 1 General

� 3 Fuel Oil

� 5 Cooling Water

� 7 Compressed Air

� 9 Lubrication Oil Systems

� 11 HVAC and Ventilation

� 13 Piping

� 15 Pneumatic Systems

� 17 Power Supply to Auxiliary Systems

� Level of details for easy use

43

Section 6: Marine Auxiliary System (DPS 2/3)

� Auxiliary systems to be arranged in accordance with the redundancy concept

� A single failure effect analysis for auxiliary systems to be included in the DP system FMEA

� Fuel water content monitoring with remote alarms is to be installed

� Power for auxiliary systems associated with DP systems is to be taken from within the redundancy group

44

Section 7: DP System Initial Test

� 1 General

� 3 DP System Performance Test

� 5 FMEA Proving Trial for DPS-2/DPS-3

� Level of details

45

Section 7: System Performance Test

� 30 minute UPS Test

� Position Reference Systems and Sensors

� Manual Position Control System

� Manual Thruster Control System

� Thruster Emergency Stop

� DP Control System

� Control and Alarms

� Standby Changeover

� Protection equipment are to be tested if they are designed to provide essential redundancy of the DP system

� 6-hour Performance Endurance Test

46

Section 7: FMEA Proving Trial for DPS-2/DPS-3

� FMEA tests to confirm the findings from FMEA analysis

� Test procedures are to be developed in the FMEA analysis

� Vessel is to operate in configurations analyzed in DP system FMEA

� Submit final version of DP FMEA including conclusions from the testing

47

Section 8: Enhanced System

� New Notations

� EHS-P for enhanced power plant and thruster system

� EHS-C for enhanced control system

� EHS-F for fire and flood tolerance design

� Supplement information for DPS-2/DPS-3 Notations

� Provide three groups for flexibility and easy recognition

� Can be combined as EHS-PC, etc.

� Objective

� Improve reliability, operability and maintainability

� Recognize safety features that beyond minimum requirements

� Encourage higher safe design standard

48

Enhanced Propulsion System EHS-P

� Applicable to DPS-2 and DPS-3 system

� Features on power plant protection and quick blackout recovery

� High safety measurement against closed bus operation

� Targeting reduced consequence of failure

49

EHS-P Requirement

� Enhanced generator protection

� Failure detection and discrimination of failed components before a

full or partial black-out situation occurs

� Open bus-tie if the faulty generator fails to trip

� One protection system per generator

� Robust redundancy design

� Autonomous generator sets

� Autonomous thruster sets

� Blackout prevention and automatic recovery (60s)

� Power management system

� Thruster phase back

� System ride through capability (short circuit)

50

EHS-P Requirement

� Autonomous

� Control and automation – to be decentralized to the point that each

item of main machinery (generators and thrusters) is capable of

making itself ready for DP operations independently of any

centralized control system

� Auxiliary – to be provided in a manner that makes the machinery

(generators and thrusters) as independent as practical to minimize

the number of failures that can lead to the loss of more than one

main item of machinery

51

Enhanced Control System EHS-C

� Applicable to DPS-2 and DPS-3 system

� Aiming for higher availability and reliability of input data to the control system

� Statistics point to the necessary of improvement

� Encourage for higher design standard

DP Computer

Environment

Power Generation

Operator Error

References

Thruster

Electrical

Incidents that led to loss of position

1994-2007

DP Computer 62

Environment 40

Power Generation 50

Operator Error 89

References 103

Thruster 76

Electrical 22

Total 442

52

EHS-C Requirement

� Three position reference systems and sensors available at any given time and location

� Four position reference systems and four sensors with combination of different systems

� Redundancy of relative reference system for offshore support vessels

� Three DP control computers (one backup)

� Equipment from different suppliers or using different principles of operation

� DP Data Logger

� Integration of the centralized control system with sub-control systems

53

Fire & Flood Tolerance Design EHS-F

� Applicable to DPS-2 system

� Provide another level of measurement for fire and flood tolerance design

� Focus on fire risk spaces

� Flexibility for diversified market needs

54

EHS-F Requirement

� DPS-3 automatically meets EHS-F requirements

� A-0 separation along boundary of redundancy groups

� No A-0 separation required between main and backup DP control station

� A-60 separation for high fire risk spaces

� The high fire risk area is the area defined by SVR 4-8-4/1.11

including

� Machinery spaces as defined by 4-7-1/11.15 and 4-7-1/11.17

� Spaces containing fuel treatment equipment and other highly

flammable substances

55

Summary of Enhanced DP Systems

EHS-P EHS-C EHS-F

Autonomous Generator Set2+1 Backup DP Control

computers and controllersGenerators and Prime Movers

Separate compartments, A60 for

high fire risk area. Watertight

below damage waterline.

Bus Tie Breakerredundantly configured

between each bus segment

Wind Sensors3 + 1 in back up control station

Enhanced Generator Protection

Gyros3 + 1 in backup control station

Power Distribution SystemA0 between redundant groups.

Watertight below damage waterline.

Enhanced Power Management

MRU3 + 1 in backup control station

Thruster SystemA0 between redundant groups.

Watertight below damage waterline.

Autonomous Thruster SetPosition Reference Systems

3 + 1 in backup control stationController Space

A0 between redundant groups.

56

Closed Bus

� Enhanced system design (EHS-P)

� Improvement of active redundancy

� Reduce consequence after failure

� At least two or more generators running and they are connected to two or more sections of the main bus

� The worst case failure of the configuration is not to result to a blackout

� Spinning reserve is to be able to make up at least 50% lost capacity after the worst case failure of the operating mode in consideration

� Other 50% lost capacity can be provided from the standby units

57

Standby Start

� Changeover is to be automatic

� Position and heading of the vessel are within the specified limits and DP

performance is not degrading

� Maximum allowed changeover time is 45s

� Single fault does not cause total blackout including loss of entire

compartment for DPS-3

� A failure in one redundancy group is not to cause failure of more than

one redundancy groups

� A failure in the system being changed over to is not to cause failure of

more than one redundancy groups

� Changeover is not to cause failure of the redundancy group that is being

connected to

� At least, one standby generator is to be considered not available when

needed

58

FMEA & Test (EHS)

� Operation of protection systems (breakers, bus ties, etc.) related to short circuit

� Severe voltage dips associated with short circuit faults in power plant configured as a common power system

� Failure to excess and insufficient fuel

� Over and under-excitation

� Governor and AVR failure modes

� Failure modes related to standby start and changeover

� Power management failure on load sharing, malfunction, etc.

� Phase back thrust and large load

� Blackout recovery

59

Documentation (EHS)

� Description of protection design philosophy and protection systems the redundancy concept of DP system depends on

� Analysis of effects of severe voltage transients on power system stability

� Short circuit analysis

� Simulation of severe over/under voltage and over/under frequency

� Protection coordination analysis

� Protection settings

� Description of automatic blackout recovery

60

Section 9: Stationkeeping Performance

� New notations

� SKP: verification for given design environmental conditions through

analysis

� SKP(a,b,c,d,e,f): determine limiting environments for a given

environment site through analysis

� Supplement for DPS-series notations

� Objective

� Recognition of DP capability

� Encourage robust design and consistent assessment

61

SKP Notation

� Owner specify design environment conditions

� Design wind speed and directions

� Design wave height, related period and directions

� Design current speed and directions

� Station keeping performance assessment

� Environmental load calculation

� Available thrust calculation including effect due to thruster

interference with others

� Analysis results demonstrate the capability of stationkeeping for the specified environment conditions

62

Result Presentation for SKP

Total Thrust Utilization Plot for given Environment Condition

63

Environmental Load

� Wind and current

� 1-minute mean wind speed at 10-meter above water surface

� Model test data to be used whenever possible

� For non-ship shape unit, wind and current forces according to

ABS Rules for MODU, FPI or API 2SK

� For a ship shape unit, wind and forces according to ABS Rules for

MODU, FPI, API RP 2SK or OCIMF publication

� Wave

� Significant wave heights and characteristic periods (frequencies)

� JONSWAP for North Sea and locations with limited fetch

� Bretschneider for open seas

� Model test data for wave drift force if available

� Drift force calculation using appropriate hydrodynamic analysis

computer program

64

Available Thrust

� Manufacturer’s test data of full scale or suitable model test for the thrust output of thrusters to be used

� This Guide provides method for determining available thrust

� Thruster-Thruster Interaction

� Thruster-Hull Interaction

� Thruster-Current Interaction

65

DP Capability

Courtesy: MTS/Shell

Predicted CapabilityReal Capability

66

SKP(a,b,c,d,e,f) Notation

� a: the probability that the vessel can remain on station with all thrusters operating for location f and current speed e

� b: the probability that the vessel can remain on station with the failure of minimum effect of single thruster for location f and current speed e

� c: the probability that the vessel can remain on station with the failure of maximum effect single thruster for location f and current speed e

� d: the probability that the vessel can remain on station with the worst case failure condition for location f and current speed e

� e: current speed in knot (owner specify or typical 1.5 kt)

� f: environment location (owner specify or typical North Sea)

67

SKP(a,b,c,d,e,f) Notation

� Same analysis procedures for load and thrust calculation

� May cover SKP if design environments are given and are within the limit

� Require for the relationship between wind speeds and wave heights

� Require probability of non-exceedance of wind speed

68

Wind & Wave Relationship (North Sea)

69

Result Presentation for SKP(a,b,c,d)

Typical DP Capability Plot

70

Section 9: Sub-sections

� 1 General

� 1.1 Definition

� 1.1.1 SKP

� 1.1.2 SKP (a,b,c,d)

� 1.1.3 Normal Operation Condition

� 1.1.4 Standby Condition

� 3 Environmental Condition

� 3.1 Wind

� 3.3 Wave

� 3.5 Current

� 3.7 Environment for SKP

� 3.9 Environment for SKP (a,b,c,d)

� 5 Analysis Conditions

� 5.1 DP System Configurations

� 5.3 Operation Conditions

� 7 Environmental Load Calculation

� 7.1 Wind and current force

� 7.3 Wave force

� 9 Other External Load

� 11 Available Thrust

� 11.1 Available Thrust for Thrusters

� 11.3 Thruster-Thruster Interaction

� 11.5 Thruster-Hull Interaction

� 11.7 Thruster-Current Interaction

� 11.9 Available Thrust for Transverse

Tunnel Thrusters

� 13 Rudder Force

� 15 SKP Calculation

� 15.1 SKP Notation

� 15.3 SKP (a,b,c,d) Notation

� 17 Documentation

71

Documentation

� Where the DP system is to be supplemented with a stationkeeping performance notation, the following information is to be submitted for review

� General arrangement and lines plan

� Thruster arrangement

� Thruster power and thrust

� Thruster interactions

� Analysis procedures

� Capability plots

� Documentation on the environment conditions long term distribution

(any area for intended service)

� Owner specified limiting environments

72

Section 10: Specific Vessel Types

� 1 Introduction

� 3 Mobile Offshore Drilling Units

� Effect of drilling

� Effect of emergency shutdown system

� Effect of emergency disconnect system

� Maintenance plan

� 5 Project or Construction Vessels

� Suitable DP Control modes

� Redundancy of relative position reference system

� 7 Logistics Vessels

� Redundancy of relative position reference system

73

DPS Guide Development Milestones

Project Plan

Initial development

work

Jan 2012 Oct 2012

Rough Draft for DP

consultants review and

improvement

Jun 2012 Aug 2012

DPS draft guide development

Industry workshop

Project KickoffDivisions

TechnologyTBDs

Previous DP Consultant work

Internal and external review

Consultantfeedback

Dec 2012

DPS Guide

Review feedback

74

Summary

� DPS Guide to reduce the gaps between industry practices and class requirements

� New notations for enhanced system (EHS) and stationkeeping performance (SKP)

� Provide systematic measurement

� Provide more flexibility for owners and operators

� Need industry feedbacks for further improvement

Shipbuilder

Underwriter

Charterer

ShippingFinancier

Classification Society

Flag State

Port State

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