dps notations: clarifying the role of...

Marine Technical SocietyDynamic Positioning Conference

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DPS Notations: Clarifying the Role of Classification

Frequently Asked Questions

Houston, Texas12-13 October 2010

George ReillyManaging Principal Engineer, Marine Technology

ABS

1994 Guide

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IMO Consequence Classes/FMEA

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Class Prescriptive Rules

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DPS notation dependent on Redundancy targets

Single point of failure

FMEA generation

Plan review

Sea trials

DPS Not Just an “Add On”

Needs to be considered throughout design Cable routes

Ventilation

Fire extinguishing

Power supplies• High power

• Control power

– Switchgear

– Sensors

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DPS Vessels Entering ABS Class

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ABS Class (1994 to 2004)

Elements of a Typical DP System

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Tunnel Thrusters

Vertical reference unit

DP Console

Acoustic Transponder

Rudders

Propellers

Weight

Gyrocompass

Anemometer DGPS

Artemis

Taut Wire PositionMeasuring System

TunnelThruster Thruster

Azimuth

Laser Reference

Acoustic Positioning System

Possible Developments

Environmental criteria

Reliability (other than through redundancy)

Different (vessel) applications

More detailed guidance

More survey guidance

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DPS Vessels Entering ABS Class

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ABS Class (2005 to 2009)

ABS Vessels with DPS Notation

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2

4

6

8

10

12

14

16

18

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2006 2007 2008 2009 2010

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%

Dynamic Positioning Systems

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Question 1

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ABS DPS Class notation numbers mirror the IMO consequence classes,

yet neither demand any particular environmental capability.

Is this an omission?

How do we verify the capability plot?

Question 2

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Question 3

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The IMO Guidance states “Bus-tie breakers should be open during

equipment class 3 operations, unless equivalent integrity of power

operation can be accepted according to…”

ABS does not have an equivalent statement, but is this intent applied?

Question 4

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ABS requires an Emergency Shut Down, but this could

introduce a single point of failure which is to be avoided for

DPS-2 and DPS-3 operations.How can ABS have such

contradictory requirements?

Question 5

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In real life equipment is subject to wear and tear and breakdowns.

What is the ABS position when equipment, which is subject to

the ABS DP Class requirements, is not available day-to day and

at the time of survey?

Question 6

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ABS requirements are silent on the subject of combined operations, but combined

operations are frequently the norm rather than the exception?

Question 7

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Last year ABS introduced more DP-specific survey requirements.

Does ABS have any plan to accept the reports of other

independent specialists in lieu of ABS surveyor attendance?

Question 8

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What about the future?

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